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Dr. Aidah Abu Elsoud Alkaissi An-Najah National University Faculty of Nursing. Patient Management: Renal System. Renal Function. Renal function may be replaced by a process called dialysis, which is a life-maintaining therapy used in acute and chronic renal failure.

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Dr aidah abu elsoud alkaissi an najah national university faculty of nursing l.jpg

Dr. Aidah Abu Elsoud Alkaissi

An-Najah National University

Faculty of Nursing

Patient Management:Renal System

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Renal Function

Renal function may be replaced by a process called

dialysis, which is a life-maintaining therapy used in

acute and chronic renal failure.

Critical care nurses may encounter patients suffering from the effects of acute renal failure or patients already on some form of chronic dialysis who subsequently become critically ill.

Critical care nurses must be familiar with various dialysis therapies to help care for patients with complex illnesses.

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Renal Function

The three most common forms of renal replacement therapy:


continuous renal replacement therapies [CRRTs],

common fluid and electrolyte imbalances experienced by critically ill patients.

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All forms of dialysis make use of the principles of osmosis and diffusion to remove waste products and excess fluid from the blood.

A semipermeable membrane is placed between the blood and a specially formulated solution called dialysate.

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Dissolved substances, such as urea and creatinine,diffuse across the membrane from an area of greater concentration (blood) to an area of lesser concentration (dialysate).

Water molecules move across the membrane by osmosis to the solution that contains fewer water molecules

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Dialysate is formulated with varying concentrations of dextrose or sodium to produce an osmotic gradient, thereby pulling excess water from the circulatory system.

This process of fluid moving across a semipermeable membrane in relation to forces created by osmotic and hydrostatic pressures is called ultrafiltration.

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Hemodialysis and the CRRTs use an extracorporeal (outside the body) circuit.

Therefore, they require access to the patient’s circulation and anticoagulation of the circuit.

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Access to Circulation

The three most common methods used to access a patient’s circulation are through a vascular catheter, an arteriovenousfistula, or a synthetic vascular graft.

Patients who suddenly need hemodialysis or CRRT have a venous catheter, whereas patients already receiving chronic hemodialysis probably have either an arteriovenous fistula or a synthetic vascular graft.

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Nursing interventions for the Patient With Dialysis Vascular AccessDual-Lumen Venous Catheter

■ Verify central line catheter placement radiographically

before use.

■ Do not inject IV fluids or medication into the catheter.

Both lumens of the catheter usually are filled with

concentrated heparin.

■ Do not unclamp the catheter unless preparing for dialysis

therapy. This can cause blood to fill the lumen and clot.

■ Maintain sterile technique in handling vascular access.

■ Observe catheter exit site for signs of inflammation or access limb.

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Arteriovenous Fistula or Graft

■ Do not take blood pressure or draw blood from the hand that have the fistula

■ Listen for bruit (reflecting turbulence of flow)

and palpate for thrill q8h.

■ Make sure there is no tight clothing or restraints on the access limb.

■ Check access patency more frequently when patients are hypotensive. Hypotension can predispose to clotting.

■ In the event of postdialysis bleeding from the needle site, apply just enough pressure to stop the flow of blood and hold until bleeding stops. Do not occlude the vessel.

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acutely ill patients who need hemodialysis, continuous venovenous hemofiltration (CVVH), or continuous venovenous hemofiltration with dialysis (CVVH/D).

Venous catheters are also used for hemodialysis when there is no other means of access to the circulation.

Veins commonly used are the femoral, internal jugular, or subclavian.

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The site chosen depends on the patient’s anatomy and vein accessibility and the physician’s experience and preference.

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Dual-lumen venous catheters also are used temporarily for patients on acute dialysis who are critically ill or patients on chronic dialysis who are waiting for a more permanent access to mature.

Tunneled dual-lumen central venous catheters are often used as a permanent means of access in patients in whom all other means of entry into the circulatory system have been exhausted.

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The tunneled catheter has an implantable Dacron cuff around which tissue grows and acts as a barrier against infection.

If possible, the catheter should be placed in the right or left internal jugular vein because catheters placed in the subclavian vein can cause stenosis.

The stenosis can cause increased venous pressure and edema that may thwart (To prevent the occurrence) future efforts to create an arteriovenous fistula or place a graft.

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Whenever venous catheters are used, care must be taken to avoid accidental slippage and dislodgement during hemodialysis.

Femoral catheters are usually secured with sutures as well as with tape to the leg, whereas central venous catheters in the upper body are sutured to the skin.

The length of time catheters are left in place depends on catheter function and institution policy. In general, central venous catheters may be used for up to 3 to 4 weeks.

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permanent internal jugular vein catheters often function for many months before problems force their removal.

Catheters left in place between dialysis treatments usually are filled with a concentrated heparin–saline solution after

dialysis and plugged to prevent clotting.

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These catheters should many months before problems force their removal.never be used for any purpose other than hemodialysis without first checking with dialysis unit personnel.

Cleansing and dressing of the insertion site are the same as with other central lines.

If the catheters are removed at the end of dialysis, pressure is applied to the puncture sites until complete clotting occurs.

The site is checked for several hours thereafter so

that any recurrent bleeding can be detected.

Removal of the more permanent tunneled catheter requires use of local anesthetic at the exit site and careful dissection around the Dacron cuff to free it from the attached subcutaneous tissue.

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Catheter patency must be maintained. Thrombolytics may be used to dissolve clots in venous catheters.

Thrombolytics are enzymes derived from streptococcal bacteria that are capable of activating the fibrinolytic system and dissolving intravascular thrombi.

These agents can help preserve vascular access and reduce the need for surgery or catheter reinsertion.

However, their use is associated with inherent risks and side effects, including local pain, bleeding, and an allergic response.

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In the early days of dialysis, vascular access was created at every treatment by cannulating an artery to remove blood from the body and a vein to return dialyzed blood to the patient.

The lines carrying blood to the dialyzer were called arterial lines, and the lines returning blood to the body were called venous lines.

The two lumens of the venous catheter used in dialysis are still designated as arterial and venous.

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The arterial lumen is longer than the venous lumen so it can catch blood flowing by and allow it to be pumped out of the body.

Blood is returned upstream from the arterial lumen to avoid pulling out the blood that has just been dialyzed and returned to the body.

The lumens are distinguished by the presence of colored clamps: red on the arterial lumen and blue on the venous lumen.

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ARTERIOVENOUS FISTULAS catch blood flowing by and allow it to be pumped out of the body.

The arteriovenous fistula technique was developed in 1966 in an effort to provide long-term access for hemodialysis.

To create the arteriovenous fistula, a surgeon anastomoses an artery and a vein, creating a fistula or artificial opening between them

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Arterial blood flowing into the venous system results in a marked dilation of the vein, which can then be punctured easily with a 15- or 16-gauge dialysis fistula needle.

Two venipunctures are made at the time of dialysis: one for blood outflow and one for blood return.

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After the arteriovenous fistula incision has healed, the site is cleansed by normal bathing or showering.

To avoid scar formation, excessive bleeding, or hematoma of the arteriovenous fistula, care is taken to avoid traumatic venipuncture, excessive manipulation of the needles, and repeated use of the same site fo venipuncture.

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Adequate pressure must be put on the puncture sites after the needles are removed.

In addition, blood pressure measurements and venipunctures should not be performed on the arm with the fistula.

Most arteriovenous fistulas are developed and ready to use 1 to 3 months after surgery.

After initial healing has occurred, patients are taught to exercise the arm to assist in vessel maturation.

They also are encouraged to become familiar with the quality of the “thrill” felt at the site of anastomosis so that they can report any change in its presence or strength.

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A loud, swishing sound termed a the needles are removed. bruit indicates a functioning fistula.

Although arteriovenous fistulas usually have a long life, complications may occur.

These include thrombosis, aneurysm or pseudoaneurysm, or arterial insufficiency causing a “steal syndrome.”

This syndrome occurs when shunting of blood from the artery to the vein produces ischemia of the hand, causing pain or coldness in the hand.

Surgical intervention can remedy all of these problems and restore adequate fistula flow.

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Caring for an Arteriovenous Fistula the needles are removed.

■ Wash the fistula site with antibacterial soap each day and always before dialysis.

■ Refrain from picking the scab (A crust discharged from and covering a healing wound) that forms after completion of dialysis therapy.

■ Check for redness, feeling of excess warmth, or the

beginning of a pimple on any area of access.

■ Ask the dialysis care team to rotate needles at the time of dialysis treatment.

■ Check blood flow several times each day by feeling for a pulse or thrill. If this is not felt, or if there is a change, call your health care provider or dialysis center.

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Caring for an Arteriovenous Fistula the needles are removed.

■Refrain from wearing tight clothes or jewelry on the

access arm. Also avoid carrying anything heavy or doing anything that will put pressure on the access site.

■ Avoid sleeping with your head on the arm where the

access site is located.

■ Remind caregivers and staff not to use a blood pressure cuff on, or draw blood from, the arm where the access site is located.

■ Apply only gentle pressure to the access site after the needle is removed. Too much pressure stops flow of blood to the access site.

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SYNTHETIC GRAFTS the needles are removed.

The synthetic graft is made from polytetrafluoroethylene (PTFE), a material manufactured from an expanded, highly porous (Full of or having pores) form of Teflon.

The graft is anastomosed between an artery and a vein and is used in the same manner as an arteriovenous fistula

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For many patients whose own vessels are not adequate for fistula formation, PTFE grafts are extremely valuable.

PTFE segments are also used to patch areas of arteriovenous grafts or fistulas that have stenosed or developed areas of aneurysm.

It is best to avoid venipuncture in new PTFE grafts for 2 to 4 weeks while the patient’s tissue grows into the graft.

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When tissue growth progresses satisfactorily, the graft has an endothelium and wall composition similar to the patient’s own vessels.

The procedures for preventing complications in grafts are the same as those used for arteriovenous fistulas.

However, certain complications are seen more frequently with grafts than with fistulas, including thrombosis, infection, aneurysm formation, and stenosis at the site of anastomosis.

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Anticoagulation an endothelium and wall composition similar to the patient’s own vessels.

  • Blood in the extracorporeal system, such as the dialyzer

  • and blood lines, clots rapidly unless some method of anticoagulation is used.

  • Heparin is the drug of choice because it is simple to administer, increases clotting time rapidly, is monitored easily, and may be reversed with protamine. Trisodium citrate 4% may also be used for CRRT.

  • This agent chelates (Chemical compounds that act as water "softening" agents. "Hard" minerals (such as calcium) are attracted to and can neutralize the surfactants in a detergent. Chelates do not remove or exchange hard minerals in water. Rather, chelate molecules surround and cover (sequester) those minerals calcium), thereby inactivating the clotting

  • cascade.

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Specific heparinization procedures vary, but the primary goal of all methods is to prevent clotting in the dialyzer with the least amount of anticoagulation.

Two methods commonly used are intermittent and constant infusion.

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SYSTEMIC ANTICOAGULATION goal of all methods is to prevent clotting in the dialyzer with the least amount of anticoagulation.

Typically, the circuit is initially primed with a dose of heparin, followed by smaller intermittent doses of anticoagulation or heparin administered at a constant rate by an infusion pump.

This results in systemic anticoagulation,in which the clotting times of the patient and the dialyzer essentially are the same.

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Definitive guidelines are difficult to provide because methods and dialyzer requirements vary.

The normal clotting time of 6 to 10 minutes may be increased to 30 to 60 minutes.

The effect of heparin usually is monitored by the activated clotting time, prothrombin time (PT), or

partial thromboplastin time (PTT).

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The patient’s need for heparinization and an appropriate beginning heparin dose should be assessed routinely before dialysis, especially in the critically ill patient who may be actively bleeding or at risk for bleeding.

The patient’s platelet count, serum calcium level, and results of coagulation studies are valuable in assessing current function

of the clotting process.

Often little or no heparin can be used when the patient has serious alterations in one or

more factors needed for effective clotting.

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REGIONAL ANTICOAGULATION beginning heparin dose should be assessed routinely before dialysis, especially in the critically ill patient who may be actively bleeding or at risk for bleeding.

Systemic heparinization does not usually present a risk unless the patient has overt bleeding (e.g., gastrointestinal bleeding, epistaxis, or hemoptysis), is 3 to 7 days postsurgery, or has uremic pericarditis.

In these situations, other methods to prevent clotting of the extracorporeal system can be used

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One method is regional heparinization, in which the patient’s clotting time is kept normal

while the clotting time of the dialyzer is increased.

This is accomplished by infusing heparin at a constant rate into the dialyzer and simultaneously neutralizing its effects with

protamine sulfate before the blood returns to the patient.

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Like systemic heparinization, regional heparinization has no associated standard heparin–protamine ratio.

Frequent monitoring of the clotting times is the best

way to achieve effective regional heparinization. Because of the rebound phenomenon that has occurred after regional heparinization, low-dose heparinization may be used, even in the presence of overt bleeding. With this method, minimal heparin doses are used throughout dialysis.

Although some clotting may take place in the dialyzer, the small blood loss is preferable to the risk of profound bleeding.

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Bleeding problems occasionally occur because of accidental heparin overdose.

This may be caused by infusion pump malfunction or an error in setting the delivery rate.

Because of the hazards, heparin delivery must be monitored carefully and frequently

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. heparin overdose.

Another way to prevent dialyzer clotting and reduce the risk of bleeding due to heparin is to infuse a small initial heparin dose (e.g., 250 U) and use frequent normal saline flushes of the extracorporeal system, or use saline

flushes alone.

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Some dialysis centers perform regional citrate anticoagulation in which citrate is infused into the system before the dialyzer binds calcium, obstructing the normal clotting pathway.

The citrate–calcium complex is then cleared from the blood by the dialyzer, and the anticoagulant effect is reversed by infusing calcium chloride before the blood returns to the patient.

The patient’s sodium levels may rise because the citrate is administered in the form of sodium citrate.

Citrate has a higher pH, and therefore patients may also become metabolically alkalotic.

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INTERMITTENT HEMODIALYSIS anticoagulation in which citrate is infused into the system before the dialyzer binds calcium, obstructing the normal clotting pathway.

In hemodialysis, water and excess waste products are removed from the blood as it is pumped by the dialysis machine through an extracorporeal circuit into a device called a dialyzer, or artificial kidney.

The blood is in one compartment, and the dialysate is in another compartment.

There, the blood flows through a semipermeable membrane.

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The semipermeable membrane is a thin, porous sheet made of cellulose or a synthetic material.

The pore size of the membrane permits diffusion of low–molecular-weight substances such as urea, creatinine, and uric acid.

In addition, water molecules are small and move freely through the membrane, but most plasma proteins, bacteria, and blood cells are too large to pass through the pores of the membrane. The difference in the concentration of the substances in the two compartments is called the concentration gradient.

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The blood, which contains waste products such as urea and creatinine, flows into the blood compartment of the dialyzer, where it comes into contact with the dialysate,which contains no urea or creatinine.

A maximum gradient is established so that these substances move from the blood to the dialysate.

These waste products fall to more normal levels as the blood passes through the dialyzer repeatedly at a rate ranging from 200 to 400 mL/minute over 2 to 4 hours

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Excess water is removed by a pressure differential created between the blood and fluid compartments.

This pressure differential is aided by the action of the dialyzer pump and usually consists of positive pressure in the blood path and negative pressure in the dialysate compartment.

This is the process of ultrafiltration.

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Hemodialysis: between the blood and fluid compartments.

■ Removes byproducts of protein metabolism, such as urea, creatinine, and uric acid

■ Removes excess water

■ Maintains or restores the body buffer system

■ Maintains or restores the level of electrolytes in the body

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Indications for Hemodialysis between the blood and fluid compartments.

Hemodialysis is indicated in chronic renal failure and for complications of acute renal failure.

These include uremia, fluid overload, acidosis, hyperkalemia, and drug overdose.

Table 30-1 compares hemodialysis, CRRT, and peritoneal dialysis.

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Contraindications to Hemodialysis between the blood and fluid compartments.

Hemodialysis may be contraindicated in patients with

coagulopathies because the extracorporeal circuit needs to be heparinized.

Hemodialysis may also be difficult to perform in patients who have extremely low cardiac output or

who are sensitive to abrupt changes in volume status.

For these critically ill patients, CRRT may be the optimal choice.

In addition, intermittent hemodialysis may not keep up with the metabolic needs of a highly catabolic


In this case, CRRT would probably be chosen.

Patients treated chronically for renal failure may be given the choice to undergo hemodialysis or peritoneal dialysis.

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Equipment between the blood and fluid compartments.


Dialyzers are designed to provide a parallel path through which blood and dialysate flow and to have a maximal membrane surface area between the two.

Dialyzers vary in size, physical structure, and type of membrane used to construct the blood compartment.

All these factors determine the potential efficiency of the dialyzer, which refers to its ability to remove water (ultrafiltration) and waste products (clearance).

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The hollow-fiber dialyzer is the most commonly used between the blood and fluid compartments.


In this design, the blood path flows through hollow fibers composed of semipermeable membrane, and

the dialysate path is encased in a rigid plastic tube.

Dialysate surrounds each hollow fiber.

This provides a large surface area to cleanse the blood.

Blood and dialysate flow in opposite directions from each other (countercurrent flow); as blood travels through the dialyzer, it is constantly exposed to a fresh flow of dialysate.

This countercurrent flow maintains the concentration gradient between the two compartments and provides the most efficient dialysis

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they are highly biocompatible. between the blood and fluid compartments.

They remove waste products efficiently, and there is little reaction between the blood and the membrane material.

Because the synthetic membranes are highly permeable to water, they should be used only with a machine that controls the amount of ultrafiltration.

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The size, efficiency, and metabolic needs of the patient are considered when choosing a dialyzer.

A patient with a larger body surface area who has greater metabolic needs benefits from use of a larger and more efficient dialyzer, whereas a patient with a smaller body surface area and lower metabolic needs benefits from a smaller, less permeable dialyzer.

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DIALYSATE considered when choosing a dialyzer.

The dialysate, or “bath,” is a solution composed of water and the major electrolytes of normal serum.

It is made in a clean system with filtered tap water and chemicals.

It isnot a sterile system; bacteria are too large to pass through the membrane, and the potential for infection of the patient is minimal.

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because bacterial byproducts can considered when choosing a dialyzer.

cause pyrogenic reactions, especially in highly permeable membranes, water used to make dialysate must be bacteriologically


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It is a mobile unit, and dialysate requirements considered when choosing a dialyzer.

are easily tailored to meet individual patient needs.

Dialysate concentrates usually are provided

by commercial manufacturers.

A standard bath usually is used for patients receiving chronic dialysis, but variations

may be made to meet specific patient needs.

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DIALYSATE DELIVERY SYSTEM considered when choosing a dialyzer.

A single delivery unit provides dialysate for one patient,

whereas a multiple delivery system may provide dialysate for as many as 20 patient units.

In either system, an automatic proportioning device and metering and monitoring devices ensure precise control of the water–concentrate ratio.

The single delivery unit is usually used in patients on

acute dialysis.

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It is a mobile unit, and dialysate requirements are easily tailored to meet individual patient needs.

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ACCESSORY EQUIPMENT tailored to meet individual patient needs.

Hardware used in most dialysis systems includes a blood pump, infusion pumps for heparin delivery, and monitoring devices for detection of unsafe temperatures, dialysate concentration, pressure changes, air, and blood leaks.

All dialysis delivery systems consist of a single

compact unit that includes the dialysate delivery equipment and blood monitoring components

Disposable items used in addition to the artificial kidney

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include dialysis tubing for transport of blood between the dialyzer and patient, pressure transducers for protection of monitoring devices from blood exposure, and a normal saline bag and tubing for priming the system before us

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HUMAN COMPONENT dialyzer and patient, pressure transducers for protection of monitoring devices from blood exposure, and a normal saline bag and tubing for priming the system before us

Expertise in the use of highly technical equipment is gained through theoretical and practical training in the clinical setting.

However, the operation and monitoring of various

kinds of dialysis equipment differ.

Reference to the manufacturer’s instruction manuals gives the nurse guidelines

for the safe operation of equipment.

The technical aspects of hemodialysis may seem overwhelming at first, but they can be learned fairly rapidly.

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A more important aspect, the critical thinking and synthesis of patient assessment data that the nurse uses when caring for a patient during dialysis, takes longer to learn

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Assessment and Management of patient assessment data that the nurse uses when caring for a patient during dialysis, takes longer to learn

The degree and complexity of problems arising during

hemodialysis vary among patients and depend on many factors.

Important variables are the patient’s diagnosis, stage

of illness, age, other medical problems, fluid and electrolyte balance, prior experience wit hemodialysis, and emotional state.

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Because an increasing number of older adults are of patient assessment data that the nurse uses when caring for a patient during dialysis, takes longer to learn

receiving dialysisit also is important to consider the normal decreases in cardiac function and other system changes due to the aging process

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PREPROCEDURE of patient assessment data that the nurse uses when caring for a patient during dialysis, takes longer to learn

A predialysis assessment is the first step in managing the patient having hemodialysis.

It consists of a review of the patient’s history and clinical findings, response to previous dialysis treatment, laboratory results (such as electrolytes), consultation with other caregivers, and the nurse’s direct assessment of the patient.

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The nurse evaluates fluid balance before dialysis so that corrective measures may be initiated at the beginning of the procedure.

Blood pressure, pulse, weight, intake and output, tissue turgor, and other symptoms assist the nurse in estimating fluid overload or depletion.

Monitoring tools, such as pulmonary artery pressure, also help determine cardiovascular fluid load

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The term corrective measures may be initiated at the beginning of the procedure.dry weight or ideal weight is used to express the weight at which fluid volume is in a normal range for a patient who is free of the symptoms of fluid imbalance.

It provides a guideline for fluid removal or replacement.

The figure is not absolute. It requires frequent review and revision, especially in patients receiving dialysis in whom frequent weight changes occur.

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After reviewing the data and while consulting with the physician, the dialysis nurse establishes objectives regarding fluid removal and restoration of electrolyte balance for the dialysis treatment.

The objectives vary from one dialysis to the next in the patient whose condition may change rapidly.

For example, fluid removal may take precedence over correction of an electrolyte imbalance, or vice versa.

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Anxiety and apprehension, especially during the first dialysis, may contribute to change in blood pressure, restlessness, and gastrointestinal upset.

The presence of a competent and caring nurse during dialysis may increase the patient’s sense of security enough to avoid the need for an antianxiety drug that might precipitate changes in vital signs.

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A basic explanation of the procedure and its place in the total care plan for the patient also may allay some of the anxiety experienced by the patient and family.

They must understand that dialysis is being used to support normal body function rather than to “cure” the kidney problem.

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PROCEDURE total care plan for the patient also may allay some of the anxiety experienced by the patient and family.

The nurse begins the procedure by checking the equipment (Box 30-3).

After predialysis preparation and a safety check of equipment, the nurse is ready to begin hemodialysis.

Access to the circulatory system is gained by one of

several options: a dual-lumen catheter, an arteriovenous

fistula, or graft.

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The dual-lumen catheter is opened under total care plan for the patient also may allay some of the anxiety experienced by the patient and family.

aseptic conditions according to institutional policy.

Two large-gauge (15- or 16-gauge) needles are needed to cannulate a graft or fistula.

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After vascular access is established, blood begins to flow, assisted by the blood pump.

The part of the disposable circuit before the dialyzer is designated the arterial line, both to distinguish the blood in it as blood that has not yet reached the dialyzer and in reference to needle placement.

The arterial needle is placed closest to the arteriovenous anastomosis in a graft or fistula to maximize blood flow.

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clamped saline bag always is attached to the circuit just before the blood pump.

In episodes of hypotension, blood flow from the patient can be clamped while the saline is opened and allowed to infuse rapidly to correct blood pressure.

Blood transfusions and plasma expanders also can be attached to the circuit at this point and allowed to drip in, assisted by the blood pump.

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Heparin infusions may be located either before or after the blood pump, depending on the equipment in use.

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The dialyzer is the next important component of the blood pump, depending on the equipment in use.


Blood flows into the blood compartment of the

dialyzer, where exchange of fluid and waste products takes place.

Blood leaving the dialyzer passes through an air

detector that shuts down the blood pump if any air is


At this point in the pathway, any medications

that can be given during dialysis are infused through a

medication port.

However, unless otherwise ordered, most medications are withheld until after dialysis.

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Blood that has passed through the dialyzer returns to blood pump, depending on the equipment in use.

the patient through the venous, or postdialyzer line.

After the prescribed treatment time, dialysis is terminated by clamping off blood from the patient, opening the saline line, and rinsing the circuit to return the patient’s blood.

A dialysis nurse is in constant attendance during acute


Blood pressure and pulse are recorded at least every half hour when the patient’s condition is stable.

All machine pressures and flow rates are checked and recorded on a regular basis.

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The nurse assesses the patient’s responses to fluid and solute removal and the condition and function of the patient’s vascular access.

Standard Precautions, one tier of the Centers for Disease Control and Prevention Isolation Guidelines, are followed.

A protective face shield and gloves are worn by the nurse performing hemodialysis because of the risk of exposure to blood.

The dialysis nurse and critical care nurse work together to care for the patient, and they must coordinate their specific patient care responsibilities.

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POSTPROCEDURE solute removal and the condition and function of the patient’s vascular access.

The results of a dialysis treatment can be determined by

assessing the amount of fluid removed (as assessed by postdialysis weight) and the degree to which electrolyte and acid–base imbalances have been corrected.

Blood drawn immediately postdialysis may show falsely low levels of electrolytes, urea nitrogen, and creatinine.

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The process of equilibration is thought to continue for some time after dialysis

because these substances move from inside the cell to the plasma.

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Complications time after dialysisDIALYSIS DYSEQUILIBRIUM

Uremia must be corrected slowly to prevent dysequilibrium syndrome, which is a set of signs and symptoms ranging from headache, nausea, restlessness, and mild mental impairment to vomiting, confusion, agitation, and seizures.

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This is thought to occur as the plasma concentration of solutes, such as urea nitrogen, is lowered.

Blood urea and nitrogen play a role in calculating the serum osmolarity.

Because of the blood–brain barrier, solutes are removed much more slowly from brain cells.

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Therefore, plasma becomes hypotonic in relation to the brain cells.

This results in a shift of water from plasma to the brain cells and causes cerebral edema and symptoms of dysequilibrium syndrome.

This syndrome can be avoided by dialyzing patients for short periods, such as 1 to 2 hours on 3 or 4 consecutive days.

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Fluid overload is treated during dialysis by removing

excess water.

Because this removal depends on shifting fluid from other body compartments to the vascular space, care must taken to avoid removing fluid so rapidly during dialysis that it leads to volume depletion.

Excessive fluid removal may lead to hypotension, and little is gained if intravenous (IV) fluids are given to correct the


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Therefore, it is better to reduce the volume cells.

overload over two or three dialyses, unless pulmonary congestion is life-threatening.

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Normal saline in bolus amounts of 100 to 200 mL is

used to correct hypotension.

Dialysis machines now aid in preventing hypotension because the amount of ultrafiltration is controlled at the push of a button.

It is also possible to vary the sodium concentration of dialysate.

A higher sodium level in the dialysate means that less sodium is removed from the blood.

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A higher serum sodium assists the body as it shifts fluid from the interstitial to the intravascular compartment.

Blood volume expanders, such as albumin, are sometimes used in patients with a low serum protein.

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The use of antihypertensive drugs in patients who from the interstitial to the intravascular compartment.

undergo dialysis may precipitate hypotension during dialysis.

To avoid this, standard practice in many dialysis

units is to omit antihypertensive drugs 4 to 6 hours

before dialysis.

Restriction of fluids and sodium before and during the dialysis phases is a more desirable method for control of hypertension.

Sedatives and tranquilizers also may cause hypotension and should be avoided, if possible.

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HYPERTENSION from the interstitial to the intravascular compartment.

Fluid overload, dysequilibrium syndrome, renin response

to ultrafiltration, and anxiety are the most frequent causes of hypertension during dialysis.

Hypertension during dialysis is usually caused by sodium and water excess.

This can be confirmed by comparing the patient’s present weight to his or her ideal or dry weight.

If fluid overload is the cause of hypertension, ultrafiltration usually brings about a reduction in the blood pressure.

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Some patients who may be normotensive before dialysis become hypertensive during dialysis.

The rise may occur either gradually or abruptly.

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MUSCLE CRAMPS hypertensive during dialysis.

Muscle cramps may occur during dialysis as a result of excess fluid removal, which results in diminished intravascular volume and reduced muscle perfusion.

Cramps are treated by lowering the rate of ultrafiltration, giving a saline bolus of 100 to 200 mL, and either administering 10 mL of 23.4% saline or increasing the sodium content of the dialysate.

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DYSRHYTHMIAS AND ANGINA hypertensive during dialysis.

Dysrhythmias and angina may occur in patients with underlying cardiac disease in response to fluid removal.

Decreasing the rate of fluid removal may help.

Medication may be needed to control cardiac rhythm.

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In CRRT, blood circulates outside the body through a highly porous filter similar to that used with hemodialysis.

The process is similar to hemodialysis in that water, electrolytes, and small to medium-sized molecules are removed by ultrafiltration.

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CRRT is accompanied by a simultaneous hypertensive during dialysis.

reinfusion of a physiological solution, and it occurs continuously for an extended period.

A pump, slightly different from that used in hemodialysis, is used and often incorporates

a weighing system so fluids can be intricately balanced hour to hour (Fig. 30-4).

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CRRTs include continuous arteriovenous hemofiltration, hypertensive during dialysis.

continuous arteriovenous hemofiltration with dialysis, continuous venovenous hemofiltration (CVVH), and CVVH with dialysis (CVVH/D; Table 30-3).

This discussion focuses primarily on CVVH and CVVH/D because these therapies are replacing the arteriovenous procedures.

Access to the circulation for CVVH and CVVH/D is the same as that used for short-term hemodialysis.

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The extracorporeal circuit is similar to the hemodialysis circuit (Fig. 30-5).

A pump is added to assist blood flow.

The rate of blood flow is typically much slower than in hemodialysis.

The ultrafiltration rate is titrated to reach an hourly goal and is based on the patient’s cardiac and pulmonary status.

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When CVVH is used, a replacement fluid is ordered circuit (Fig. 30-5).

and is connected either before or after the filter, dependin on patient characteristics and institutional practice.

When dialysis is added to the CVVH process, it is called CVVH/D.

Adding the dialysate increases the ability to remove wastes.

Therefore, it is used when uremia must be aggressively managed, such as with the highly catabolic patient.

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CVVH and CVVH/D can be performed and managed by the critical care nurse.

Typically, competency assessment and validation are performed before the nurse cares for patients with CRRT.

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Indications for Continuous Renal care nurse.Replacement Therapy

CRRT is indicated in the following circumstances:

In patients with a high risk of hemodynamic instability who do not tolerate the rapid fluid shifts that occur with hemodialysis,

in those who require large amounts of hourly IV fluids or parenteral nutrition, and in those who need more than the usual 3- to 4-hour hemodialysis treatment to correct the metabolic imbalances of acute renal failure.

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CVVH is used when patients primarily care nurse.

need excess fluid removed, whereas CVVH/D is used when patients also need waste products removed due to uremia.

For a comparison of CRRT with hemodialysis

and peritoneal dialysis, see Table 30-1.

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Contraindications to Continuous care nurse.Renal Replacement Therapy

Renal Replacement Therapy

CRRT is contraindicated once patients become hemodynamically stable or no longer require continuous therapy, and intermittent hemodialysis should be used.

It may be difficult to achieve access to circulation in some patients with coagulopathies, which may prolong initiation of therapy.

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Patient and family discussion is imperative care nurse.

before initiation of therapy; patients may not wish to receive CRRT, and it is essential that patient wishes be considered.

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Equipment care nurse.


A typical CVVH/D setup

Blood exits the body through the arterial limb of the vascular access.

The first infusion line shown is for th anticoagulation.

Located just before the blood pump is a line that measures pressure in the prefilter portion of the circuit, known as the arterial pressure.

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The blood pump, which propels care nurse.

blood into the filter, is next.

An infusion port just after the blood pump is usually connected to normal saline for flushing the circuit or for attaching the replacement fluid.

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A bag of dialysate is shown flowing through the filter and surrounding the hollow fibers in which the blood travels.

As the dialysate exits the filter, it passes through a sensor that detects microscopic amounts of blood, thereby warning of filter rupture.

The dialysate and excess fluid removed from the patient are collected in a graduated collection device for easy measurement.

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Meanwhile, the blood exits the filter and surrounding the hollow fibers in which the blood travels.

passes into a drip chamber, where air and foam are trapped instead of entering the patient’s circulation.

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The drip chamber also contains a line to which a syringe can be attached to raise and lower the blood level and another line that measures pressure in the postfilter section of the circuit, known as venous pressure.

A clamp is located after the drip chamber and automatically engages if air tries to pass through it.

The arterial and venous pressure transducers are protected by a disposable filter.

As blood returns to th body, replacement fluid is infused.

In some systems, the line for replacement fluid is placed before the blood pump so it can be infused before the blood reaches the filter.

The total amount of blood in the circuit is about 150 mL.

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Assessment and Management be attached to raise and lower the blood level and another line that measures pressure in the postfilter section of the circuit, known as venous pressure.PREPROCEDURE

Baseline hemodynamics, vital signs, and weight are

obtained before initiation of therapy.

The filters used in the continuous therapies are much more porous than those used in hemodialysis, and the circuit does not contain a mechanism to control the amount of fluid removed.

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The potential exists for uncontrolled losses of a large amount of fluid.

Because of this, an hourly fluid balance goal is set by the physician.

Fluid is replaced each hour in varying

amounts to achieve the goal

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PROCEDURE amount of fluid.

Before therapy is initiated, the equipment is checked

The lines and filter are primed to expel air from the circuit.

Arterial and venous lines are connected to the corresponding port of the access catheter, and the blood pump is turned on.

Blood starts to flow through the tubing.

Ultrafiltration begins to produce plasma water (ultrafiltrate) that starts to flow into thecollection device

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Most experts recommend controlling the amount of ultrafiltrate by raising or lowering the collection device until the desired hourly rate of ultrafiltration is achieved.

Blood flow rates through the circuit

average 100 mL/hour, and the standard dialysate flow rate is 1 L/hour.

Substances are adequately cleared when ultrafiltration produces 500 to 600 mL/hour of


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Anticoagulation, if indicated, is administered as therapy begins.

Low-dose heparin is the standard anticoagulant

used in patients at risk of bleeding.

It may be used along with saline flushes to prevent circuit clotting.

Saline flushes without low-dose heparin may be used

when the patient has a low platelet count.

A typical protocol is to flush 100 mL through the circuit every half hour.

Another method of anticoagulation is to infuse 4% trisodium citrate before the filter.

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This anticoagulates only the extracorporeal part of the circuit.

It chelates calcium, which is then replaced through infusion in a central line.

For this process to be effective, the dialysate solution must be calcium free.

The patient needs to be closely monitored to prevent hypercalcemia or hypocalcemia

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Hourly maintenance of the CVVH/D system includes measuring blood and dialysate flows, calculating net ultrafiltration and replacement fluid, titrating anticoagulants, assessing the integrity of the vascular access, and monitoring hemodynamic parameters and blood circuit pressures.

The nephrologist sets a goal for hourly fluid

balance, and the critical care nurse is responsible to see that it is met.

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The amount of replacement fluid is determined by the difference between desired and net fluid balance.

Fluid balance and replacement should be recorded on a bedside flow sheet.

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In CVVH, replacement fluid may be infused prefilter or postfilter.

Both techniques have advantages and disadvantages.

When fluid is given prefilter, it decreases blood viscosity and increases blood flow through the filter.

This enhances ultrafiltrate (plasma fluid) production and solute removal and decreases the frequency of clotting.

The disadvantage is the increased need for fluid replacement.

If replacement fluid is given postfilter, there is less total fluid loss and less need for replacement fluid.

However, there is an increased incidence of filter clotting and decreased filter life.

The method chosen depends on the system used and institutional preference.

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Electrolytes, urea nitrogen, creatinine, and glucose postfilter.

levels are drawn before the procedure is started and then at least twice daily.

Electrolyte imbalances can be corrected by altering the composition of the replacement fluid or by custom-mixing the dialysate.

Anticoagulation is monitored by checking activated clotting times or PT and PTT.

Although frequency is determined by each institution, it is not unusual to check clotting times every 1 or 2 hours to prevent clotting of the filter and blood lines.

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No one policy delineates the optimal time to change postfilter.

the circuit.

Many institutions put a 24- to 48-hour limit on circuit life, although there are reports of filters lasting an average of 4 days.

System performance is monitored by checking the amount of urea nitrogen in the filtrate compared with the amount of urea nitrogen prefilter.

A decreasing ratio indicates inadequate performance.

A decreasing rate of ultrafiltration and increases in the venous pressure indicate clotting in the filter.

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Treatment may be interrupted to transport the postfilter.

patient for a diagnostic test or procedure to fix a mechanical problem with the circuit or vascular access.

Treatment may be terminated if the patient shows signs of recovering renal function.

When it is determined that continuous therapy can be terminated, the blood is returned to the patient.

First, the ultrafiltrate outlet is clamped, and the dialysate is turned off.

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Then, anticoagulation is turned off, and the blood is returned to the patient through a saline flush.

Once the lines are clear, they are disconnected from the vascular access.

Then the vascular access is heparinized per unit policy.

Documentation includes fluid balance, condition of the access, and the patient’s response to treatment.

The tubing and filter are disposable.

When working with the circuit and ultrafiltrate, the nurse uses Standard Precautions.

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Technical Complications returned to the patient through a saline flush.in Continuous Venovenous Hemofiltration With DialysisACCESS PROBLEMS

hemodialysis, making it more likely that a catheter will

provide adequate flow.

However, a poorly functioning access jeopardizes (present a danger to) the entire CVVH/D procedure.

Often, the position of the patient’s extremity affects blood flow.

If the access is in a limb, the limb should be gently immobilized.

An obstruction, such as a clot or kink in the arterial lumen of the catheter, results in less blood being delivered to the circuit and manifests as lowered arterial and venous pressures.

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Clots or kinks in the venous lumen of the catheter raise venous pressures as blood tries to return against an obstruction.

The treatment may be temporarily halted (To stop) while the nurse manually flushes each lumen to determine patency.

If blood flow still cannot be established, the nephrologist is notified immediately to replace the catheter.

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CLOTTING venous pressures as blood tries to return against an obstruction.

An early sign of filter clotting is a reduced rate of ultrafiltration, which cannot be corrected by increasing blood flow or by lowering the collection device.

As clotting progresses, venous pressure rises, arterial pressure drops, and the blood lines appear dark.

Clotting times are low.

A saline bolus may help determine the location and extent of clotting.

It may be possible to return some of the patient’s blood before changing the circuit, but if clotting is extensive

this should not be attempted.

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AIR IN THE CIRCUIT venous pressures as blood tries to return against an obstruction.

If the connections are loose, or a prefilter infusion line runs dry, air disrupts the system by collecting in the drip chamber and setting off the air detector alarm and triggering the clamp on the venous line to close.

The nurse assesses the circuit’s integrity to detect the source of air.

Before resetting the line clamp, the nurse makes sure all bubbles have been tapped (To draw ) out of the drip chamber, all connections are tight, and there is no danger of air getting into the patient’s bloodstream.

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BLOOD LEAKS venous pressures as blood tries to return against an obstruction.

Blood appears in the ultrafiltrate if there is any rupture inside the filter.

The blood leak alarm sounds and the blood pump stops. Testing the ultrafiltrate with a dipstick can verify a microscopic leak.

Blood can be safely returned to the patient as long as there is no gross blood in the ultrafiltrate. Then the circuit should be changed

A gross (visible to the naked eye) leak is readily identifiable.

Blood should not be returned to the patient, and the patient’s hematocrit should be checked to determine the need for transfusion.

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Physiological Complications in Continuous Venovenous Hemofiltration With Dialysis


If blood pressure and intravascular filling pressures fall below optimal, the nurse can increase the infusion rate of replacement fluid or give a normal saline bolus of 100 to 200 mL.

At the same time, the ultrafiltrate collection device is raised to decrease ultrafiltration until pressures stabilize.

An infusion of 5% albumin may also help stabilize blood pressure. If this situation persists, the physician

is consulted to adjust the net ultrafiltration goal.

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HYPOTHERMIA Hemofiltration With Dialysis

Some patients experience chills and lowered body temperature while their blood is circulating outside the body.

If this happens, it may be advisable to use a blood warmer

to warm either the dialysate or the replacement fluid.

Advancements in the technologies used to perform CRRT

have improved the precision of fluid balance and reduced

the hypothermia that can develop with any extracorporeal


The primary development therapy has been the

automatic fluid weighing system, which automates all

intake and output fluid calculation

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Psychological Aspects of Renal Replacement Therapies Hemofiltration With Dialysis

The psychological impact of short-term renal replacement

therapy is different from that of lifelong therapy.

Although the patient depends on a machine in both situations, in short-term therapy there is usually hope that

the patient may recover renal function.

Therefore, concerns usually focus on the discomfort associated with insertion of the temporary vascular access and the dialysis treatment.

Once these situations are handled, the patient and family then must cope with the uncertainty of how long renal failure will last and how long dialysis will be necessary

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Patients who develop chronic renal failure must deal Hemofiltration With Dialysis

with the fact that renal replacement therapy will be necessary for the rest of their lives.

At first, patients usually deny a great deal of what is happening to them.

This may continue for some time and prevent some patients from accepting necessary aspects of their treatment regimen.

Other patients who feel considerably better after starting dialysis may enter a “honeymoon phase” and appear quite euphoric (A feeling of great happiness or well-being) for a while.

Patients should progress through the normal grieving stages and develop healthy coping mechanisms to deal with their long-term treatment.

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Hemodialysis Applied to Other Therapies Hemofiltration With Dialysis

The technical equipment and knowledge needed to perform hemodialysis are often applied to other therapies that involve an extracorporeal blood process, such as hemoperfusion and therapeutic apheresis.

Hemoperfusion is used primarily for the treatment of drug overdose.

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Blood is pumped from the body and perfused through a Hemofiltration With Dialysiscolumn of charcoal or other absorbent materials that bind the drug.

This leads to a rapid reduction in serum levels and avoids potential tissue damage caused by an abnormally high drug level.

This therapy is particularly useful for drugs that are fat bound or whose molecular structure is too large to be removed by hemodialysis.

A hemodialysis blood pump and air detector often are used with hemoperfusion cartridges and tubing.

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Therapeutic plasma exchange, or Hemofiltration With Dialysisapheresis, is another therapy that may be performed using standard hemodialysis equipment in conjunction with a plasma separator cell and replacement fluids.

Apheresis is used to treat diseases caused or complicated by circulating immune complexes or their abnormal proteins.

During the procedure, the patient’s whole blood is separated into its major components, and the offending components are removed.

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PERITONEAL DIALYSIS Hemofiltration With Dialysis

same objective and operate on the same principle of diffusion.

In peritoneal dialysis, the peritoneum is the semipermeable membrane, and osmosis is used to remove fluid, rather than the pressure differentials used in hemodialysis.

To access the peritoneal cavity, a Tenckhoff (peritoneal) catheter is inserted

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Intermittent peritoneal dialysis is an effective alternative method of treating acute renal failure when hemodialysis is not available or when access to the bloodstream is not possible.

It sometimes is used as an initial treatment for renal failure while the patient is being evaluated for a hemodialysis program.

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Peritoneal dialysis has the following advantages over hemodialysis:

■ The required technical equipment and supplies are less complicated and more readily available.

■ There is less need for highly skilled personnel.

■ The adverse effects associated with the more effi-cient hemodialysis are minimized. This may be important for patients with severe cardiac disease who cannot tolerate rapid hemodynamic changes.

Peritoneal dialysis also has a few disadvantages.

■ It requires more time to remove metabolic wastes adequately and to restore electrolyte and fluid balance.

■ Repeated treatments may lead to peritonitis.

■ Long periods of immobility may result in complications,such as pulmonary congestion and venous stasis.

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Because fluid is introduced into the peritoneal cavity, peritoneal dialysis is contraindicated in patients who have existing peritonitis, in those who have undergone recent or extensive abdominal surgery, and in those who have abdominal adhesions.

In the event of a cardiac arrest, the patient’s abdomen is drained immediately to maximize the efficiency of chest compressions.

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Equipmen- peritoneal dialysis is contraindicated in patients who have existing peritonitis, in those who have undergone recent or extensive abdominal surgery, and in those who have abdominal adhesions. SOLUTIONS

As in hemodialysis, peritoneal dialysis solutions contain “ideal” concentrations of electrolytes but lack urea, creatinine, and other substances that are to be removed.

Unlike dialysate used in hemodialysis, solutions must be sterile.

Dextrose concentrations of the solutions vary; a 1.5%, 2.5%, or 4.25% dextrose solution can be used.

Use of 2.5% or 4.25% solutions usually is reserved for more fluid removal and occasionally for better solute clearance.

If peritoneal dialysate does not contain potassium, a small

amount of potassium chloride may have to be added to the

dialysate to prevent hypokalemia.

The patient’s serum potassium must be monitored closely to regulate the amount of potassium to be added

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AUTOMATED PERITONEAL DIALYSIS SYSTEMS peritoneal dialysis is contraindicated in patients who have existing peritonitis, in those who have undergone recent or extensive abdominal surgery, and in those who have abdominal adhesions.

Automated peritoneal dialysis systems have built-in monitors and a system of automatic timing devices that cycle the infusion and removal of peritoneal fluid.

For this reason, they are called cyclers, and they may be used in the intensive care setting.

They are convenient because they eliminate the need to change solution bags constantly.

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Most cyclers also have a log that retains cycle-by-cycle information on ultrafiltration.

Setting up the cycler requires attaching the appropriate strength of large-volume (5 L) solution bags to the cycler tubing, using aseptic technique.

The cycler is programmed to deliver a set amount of dialysate per exchange for a certain length of time.

When the time is up, the patient is automatically drained and then refilled.

Cyclers are usually used when patients have a permanent peritoneal access device.

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Assessment and Management information on ultrafiltration. PREPROCEDURE

Before peritoneal dialysis begins, the nurse must perform the following interventions:

Prepare the patient for catheter insertion and the dialysis procedure by giving a thorough explanation of the procedure. A consent form may be signed according to hospital policy.

2. Ask the patient to empty the bladder just before

the procedure to avoid accidental puncture with the trocar.

3. Give a preoperative medication, as ordered, to enhance relaxation during the procedure.

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4. Warm the dialyzing fluid to body temperature or slightly warmer, using a device manufactured solely for this purpose.It is not recommended that peritoneal dialysate be warmed in microwave ovens due to uneven heating of the fluid and inconsistency from one microwave to another.

5. Take and record baseline vital signs, such as temperature, pulse, respirations, and weight. An inbed

scale is ideal for frequent monitoring of the patient’s weight.

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6. Take the patient warmer, using a device manufactured solely for this purpose.It is not recommended that peritoneal dialysate be warmed in microwave ovens due to uneven heating of the fluid and inconsistency from one microwave to another.’s history, identifying abdominal surgery or trauma.

7. Examine the abdomen before the catheter is inserted.

8. Follow specific orders, obtained before the procedure, regarding fluid removal, replacement, and drug administration.

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PROCEDURE warmer, using a device manufactured solely for this purpose.It is not recommended that peritoneal dialysate be warmed in microwave ovens due to uneven heating of the fluid and inconsistency from one microwave to another.

The following items are needed for the procedure:

■ Peritoneal dialysis administration set

■ Peritoneal dialysis catheter set, which includes the

catheter, a connecting tube for connecting the catheter

to the administration set, and a metal stylet

■ Trocar set of the physician’s choice

■ Ancillary(A term used to describe additional services performed that are related to care, such as lab work, x-ray and anesthesia) drugs: local anesthetic solution (2% lidocaine),aqueous heparin (1,000 U/mL), potassium chloride, broad-spectrum antibiotics

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The physician makes a small midline incision just below the umbilicus under sterile conditions.

A trocar is inserted through the incision into the peritoneal cavity.

The obturator is removed, and the catheter is inserted and secured.

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The dialysis solution flows into the abdominal cavity by gravity as rapidly as possible (5 to 10 minutes)

If it flows in too slowly, the catheter may need to be repositioned. When the solution is infused, the tubing is clamped, and the solution remains in the abdominal cavity for 30 to 45 minutes.

Next, the solution bottles or bags are placed below the abdominal cavity, and the fluid is drained out of the peritoneal cavity by gravity.

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If the system is patent and the catheter well placed, the fluid drains in a steady, forceful stream.

Drainage should take no more than 20 minutes.

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This cycle is repeated continuously for the prescribed time, which varies from 12 to 36 hours, depending on the purpose of the treatment, the patient’s condition, and the proper functioning of the system.

Dialysis effluent is considered a contaminated fluid, and gloves are worn while handling it.

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POSTPROCEDURE which varies from 12 to 36 hours, depending on the purpose of the treatment, the patient

After the procedure, the nurse must perform the following interventions:

1. Maintain accurate records of intake and output

and weights obtained from the same scale for assessment of volume depletion or overload.

2. Monitor blood pressure and pulse frequently.

Orthostatic blood pressure changes and increased pulse rate are valuable clues that help the nurse evaluate the patient’s volume status.

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3. Detect signs and symptoms of peritonitis early. which varies from 12 to 36 hours, depending on the purpose of the treatment, the patient

Low-grade fever, abdominal pain, and cloudy peritoneal fluid all are possible signs of infection.

4. Maintain sterility of the peritoneal system. Masks

and sterile gloves must be worn while the abdominal dressing is being changed. Solution bags or bottles are changed in as controlled a physical environment as possible to avoid contamination (e.g., avoiding areas of high traffic and high air flow)

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5. Detect and correct technical difficulties early before which varies from 12 to 36 hours, depending on the purpose of the treatment, the patient

they result in physiological problems. Slow outflow

of the peritoneal fluid may indicate early problems

with the patency of the peritoneal catheter.

6. Prevent complications of bed rest and provide an

environment that helps the patient in accepting

bed rest for prolonged periods.

7. Prevent constipation. Difficult or infrequent

defecation decreases the clearance of waste products

and cause the patient more discomfort and


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Technical Complications which varies from 12 to 36 hours, depending on the purpose of the treatment, the patientINCOMPLETE RECOVERY OF FLUID

The fluid that is removed should equal or exceed the amount inserted. Commercially prepared dialysate contains approximately 1,000 to 2,000 mL of fluid. If, after several exchanges, the volume drained is less (by 500 mL or more) than the amount inserted, an evaluation must be made.

Signs of fluid retention include abdominal distension orcomplaints of fullness.

The most accurate indication of the amount of unrecovered fluid is weight

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If the fluid drains slowly, the catheter tip may be buried (to put an end to) in the omentum or clogged (An obstruction or hindrance) with fibrin.

Turning the patient from side to side, elevating the head of the bed, and gently massaging the abdomen may facilitate drainage.

If fibrin or blood exists in the outflow drainage, heparin needs to be added to the dialysate. The specific dose, which is ordered by the physician, is 500 to 1,000 U/L.

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LEAKAGE AROUND THE CATHETER (to put an end to) in the omentum or clogged (An obstruction or hindrance) with fibrin.

Superficial leakage after surgery may be controlled with

extra sutures and a decrease in the amount of dialysate

instilled into the peritoneum.

Increases in intra-abdominal pressure may also cause dialysate leaks. Therefore, continued vomiting, coughing, and jarring movements should be avoided during the initial postoperative period.

The abdominal dressing must be checked frequently to detect leakage.

Dialysate leaks can be distinguished from other clear fluids by checking with a dextrose test strip.

Dialysate tests positive because of its dextrose content.

A leaking catheter must be corrected because it acts as a pathway for bacteria to enter the peritoneum.

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BLOOD-TINGED PERITONEAL FLUID (to put an end to) in the omentum or clogged (An obstruction or hindrance) with fibrin.

Blood-tinged peritoneal fluid is expected in the initial out-flow but should clear after a few exchanges.

Gross bleeding at any time is an indication of a more serious problem and must be investigated immediately.

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Physiological Complications (to put an end to) in the omentum or clogged (An obstruction or hindrance) with fibrin. PERITONITIS

Peritonitis is a serious, but manageable,complication of peritoneal dialysis.

Signs of peritonitis include low-grade fever, abdominal pain when fluid is being inserted, and cloudy peritoneal drainage fluid.

Early detection and treatment reduces the patient’s discomfort and prevents more serious complications.

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Treatment begins as soon as a sample of peritoneal fluid is obtained for culture and sensitivity.

The patient is started on a broad-spectrum antibiotic, which is usually added to the dialysate solution, although it also can be given intravenously.

Depending on the severity of the infection, the patient’s condition should improve dramatically after 8 hours of antibiotic therapy.

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CATHETER INFECTION obtained for culture and sensitivity.

During the daily dressing change, the nurse examines the exit site closely for signs of infection, such as tenderness, redness, and drainage around the catheter.

In the absence of peritonitis, a catheter infection usually is treated with an oral, broad-spectrum antibiotic. Box 30-8 lists nursing interventions for preventing infections during peritoneal


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HYPOTENSION obtained for culture and sensitivity.

Hypotension may occur if excessive fluid is removed.

Vital signs are monitored frequently, especially if a hypertonic solution is used.

Lying and sitting blood pressure readings are especially useful for evaluating fluid status.

Progressive drops in blood pressure and weight are signs of fluid deficit.

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HYPERTENSION AND FLUID OVERLOAD obtained for culture and sensitivity.

If all the dialysate solution is not removed in each cycle,

hypertension and fluid overload may occur.

If there is hypertension and a weight increase, the nurse assesses catheter patency and notes the exact amount of fluid in the dialysate bottle.

Some manufacturers add 50 mL to a 1,000-mL bottle.

Over a period of hours, this can make a considerable difference

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The nurse also observes the patient for signs of respiratory distress and pulmonary congestion.

In the absence of other symptoms of fluid overload, hypertension may be the result of anxiety and apprehension.

Nonpharmacological measures to reduce anxiety are preferable to administering sedatives and tranquilizers.

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HIGH BLOOD UREA NITROGEN distress and pulmonary congestion.


Blood urea nitrogen and creatinine levels are closely monitored because they help evaluate the effectiveness of the dialysis.

When levels remain high, it indicates inadequate clearance of these waste products.

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HYPOKALEMIA distress and pulmonary congestion.

The serum potassium is monitored closely because hypokalemia is a common complication of peritoneal dialysis.

When the serum potassium level is low, potassium chloride is added to the dialysate.

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HYPERGLYCEMIA distress and pulmonary congestion.

Supplemental insulin can be added to the dialysate to control hyperglycemia.

Blood glucose levels should be monitored

closely in patients with diabetes mellitus and hepatic disease.

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PAIN distress and pulmonary congestion.

Patients may experience mild abdominal discomfort at any time during the procedure.

It is probably related to the constant distension or chemical irritation of the peritoneum.

If a mild analgesic does not provide relief, inserting 5 mL of 2% lidocaine directly into the catheter may help.

The patient may be more comfortable if nourishment

is given in small amounts, when the fluid is

draining out rather than when the abdominal cavity is distended.

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Severe pain may indicate more serious problems of infection or paralytic ileus.

Infection is not likely in the first 24 hours.

Aseptic technique and prophylactic antibiotics

minimize the risk of infection.

Periodic cultures of the outflowing fluid help in the early detection of pathogenic organism

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IMMOBILITY or paralytic ileus.

Immobility may lead to hypostatic (cognestion due to setting of blood by gravitation) pneumonia, especially in the debilitated or older patient.

Deep breathing, turning, and coughing should be encouraged during the procedure.

Leg exercises and the use of elastic stockings may prevent the development of venous thrombi and emboli.

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DISCOMFORT or paralytic ileus.

Peritoneal dialysis results in slower clearance of waste

products than hemodialysis; therefore, it is rarely associated with the dysequilibrium seen with hemodialysis.

However, boredom (the feeling of being displeased) is a frequent problem because the treatment is longer.

Nursing measures are directed toward making the patient as comfortable as possible.

Diversions such as reading, watching television, and visitors should be encouraged.

Educating the patient about peritoneal dialysis and involving the patient in the care may reduce some of the anxiety and discomfort.

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Peritoneal Dialysis as a Chronic Treatment or paralytic ileus.

Intermittent peritoneal dialysis (IPD) has been used for chronic therapy for some time, but it requires the patient to remain stationary for 10 to 14 hours, three times per week.

Because of this inconvenience to the patient and increased staff time needed if this therapy is performed in center, IPD seldom is used and is not available in many dialysis centers.

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Peritoneal dialysis has gained popularity as a chronic or paralytic ileus.

form of dialysis therapy, especially since continuous

ambulatory peritoneal dialysis (CAPD) has become available.

CAPD is easily taught to patients and does not limit

ambulation between dialysate fluid exchanges.

It uses the dialysis fluid that is continuously present in the peritoneal cavity 24 hours a day, 7 days a week.

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Dialysis fluid is drained by the patient and replaced with fresh solution three to five times per day.

The number of solution exchanges needed per day depends on the patient’s individual needs.

Although the patient is required to perform dialysis techniques every day, CAPD is attractive to many patients with end-stage renal disease (ESRD) because they can accomplish it easily and independently.

CAPD may also be preferred in patients who benefit from a slow, continuous removal of sodium and water, such as in those with refractory (Resistant to treatment) congestive heart failure.

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with refractory congestive heart failure. Continuous cyclic peritoneal dialysis (CCPD) is another variation of chronic peritoneal dialysis therapy.

Patients who choose this form of therapy perform IPD at night during sleep using a cycling machine and in the morning instill dialysis fluid, which remains in the abdomen during the whole day.

This is most convenient for patients who require the help of working family members to perform their exchanges.

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As with acute peritoneal dialysis, peritonitis is the greatest potential problem with chronic forms of dialysis.

Peritoneal catheters are permanent and inserted in the operating room.

Such catheters have one or two Dacron cuffs that the surgeon sutures to the abdominal wall or subcutaneous tissue or both to anchor the catheter and provide a permanent seal against invading bacteria.

Patients are taught how to recognize any potential problem associated with the catheter or treatment and to seek help from the CAPD team when needed.

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Patients who perform IPD, CAPD, or CCPD at home usually visit the dialysis unit every 4 to 8 weeks.

At this time, a nursing assessment is performed, techniques are reviewed, and required blood studies are obtained.

All health team members, including the physician, nurse, dietitian, and social worker, work together with the patient and family to ensure successful adaptation to the chosen mode of treatment.

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MANAGEMENT visit the dialysis unit every 4 to 8 weeks. OF RENAL DYSFUNCTION

When the kidneys fail, treatment such as dialysis may be used to achieve fluid and electrolyte balance.

Pharmacological treatment may be initiated to enhance an already functional kidney, attempt to recover renal function, or optimize fluid balance.

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Diuretics visit the dialysis unit every 4 to 8 weeks.

Diuretics are drugs that promote fluid removal through

increased urine production.

There are three major classes of diuretics: loop, thiazide, and potassium-sparing. Table 30-5 presents information about the various diuretics.

In addition, acetazolamide and mannitol may be used to promote fluid removal.

The ultimate goal of diuretic therapy is to improve cardiopulmonary status.

It may be necessary to use combination therapy to achieve the desired therapeutic end point.

Drugs from different classes are chosen to maximize urine production in combination therapy.

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Diuretics may be administered orally or intravenously. visit the dialysis unit every 4 to 8 weeks.

The effect is more immediate with IV therapy.

The patient is monitored for breath sounds, pulmonary pressure, and peripheral edema to determine his or her response to therapy.

Careful laboratory assessment of the blood urea nitrogen and creatinine level is required to monitor for development or worsening of acute renal failure.

Ideally, the patient’s pulmonary status and fluid balance improve while the glomerular filtration rate remains normal.

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Overdiuresis is the most common side effect. visit the dialysis unit every 4 to 8 weeks.

The nurse must monitor for fluid volume depletion, especially when diuretic regimens are altered or initiated.

Other side effects include hyponatremia, hypokalemia, hyperkalemia, hypocalcemia, hypercalcemia, hypomagnesemia, and acid– base disturbances.

A reduction in volume from vomiting, third-spacing of fluid, diuretic therapy, or other conditionsmay have the same consequences.

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A reduction in the effective circulatory volume can lead to acute renal failure, put increased work on the heart, and result in many metabolic derangements.

The most effective management strategy is to replace only that volume required to achieve adequate perfusion.

In cases where a delicate balance exists between

diuresis and overdiuresis, a pulmonary artery catheter may be inserted to guide therapy.

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Hypokalemia is another common side effect of diuretics, particularly the loop and thiazide diuretics.

In general, hypokalemia is a benign condition that can be managed effectively wit potassium supplementation.

If left untreated, patients may experience harmful, sometimes life-threatening, cardiac dysrhythmias.

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Vasoactive Drugs particularly the loop and thiazide diuretics.

Sometimes the cause of decreased effective circulatory volume is reduced cardiac contractility.

This compensation can put an increased burden on the failing heart.

In such a case, an inotropic agent (such as dobutamine or milrinone) may be added to the plan of care to improve the forward flow of the heart, thereby improving the effective circulatory volume and stopping the cascade of counterproductive compensatory mechanisms.

A failing heart, such as in congestive heart failure, can cause reduced blood flow to the kidney and potentiate acute renal failure

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The same compensatory mechanisms used in volume depletion operate in an attempt to restore renal function.

Namely, the renin– angiotensin–aldosterone system is activated to increase sodium and water retention and achieve renal and peripheral vasoconstriction.

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Dopamine is a vasoactive drug at higher doses but can stimulate dopamine receptors in the kidneys when infused at lower doses.

Stimulation of dopamine receptors causes renal vasodilation and increase renal blood flow.

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This practice is commonly used to prevent or treat acute renal failure in some settings, several studies have found that there is no improvement in clinical outcome and a lack of sufficient clinical evidence to support its routine use.

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DISORDERS OF FLUID VOLUME renal failure in some settings, several studies have found that there is no improvement in clinical outcome and a lack of sufficient clinical evidence to support its routine use.

Critically ill patients often have imbalances in fluid homeostasis related to their primary underlying disease.

Fluid imbalance occurs when there is an excess or deficit of fluid and may be either absolute or relative.

Medications, such as diuretics, put patients at increased risk of fluid imbalance.

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Infection increases metabolic demand and insensible loss, and fluid volume deficits may develop.

Regardless of patient diagnosis, assessment of fluid balance and careful management are main stays of patient care in the critical care setting.

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Fluid Volume Deficit and fluid volume deficits may develop.

When fluid loss exceeds intake, a fluid volume deficit exists.

A fluid volume deficit is a physiological situation in which fluids are lost in an isotonic fashion (both fluid and electrolytes are lost together).

Dehydration is the loss of water alone, resulting in a hyperosmolar state.

Although the critically ill patient typically can have both a fluid volume deficit and dehydration states simultaneously, this discussion is limited strictly to disorders of fluid volume deficit.

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Several patient populations are particularly vulnerable to development of fluid volume deficits.

Young children at prespeech developmental levels cannot communicate thirst; therefore, during times when fluid requirements increase, they do not increase their fluid intake of their own accord.

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Debilitated patients, such as patients after stroke, may not be able to communicate their needs or have swallowing disturbances and cannot manage their own intake of fluid.

Elderly patients are at particular risk of a fluid volume deficit because of the multisystem changes associated with aging.

For a review of the changes associated with aging and nursing implications for fluid volume assessment and management, see Table 30-2.

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CAUSES be able to communicate their needs or have swallowing disturbances and cannot manage their own intake of fluid.Gastrointestinal Loss

Physiologically, the body produces approximately 5 L of gastrointestinal fluid.

In the gastrointestinal tract, fluids help to act as a carrier of important enzymes and buffers to aid in digestion.

In the distal small intestine and large intestine, fluid is reabsorbed, leaving only approximately 150 mL lost through the stool daily.

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Excess loss from any site from which fluids are ordinarily lost may cause a fluid imbalance.

Conditions such as vomiting and diarrhea may cause an increase beyond the typical 150 mL and result in a fluid volume deficit.

In addition, surgically placed drainage tubes and nasogastric tubes used for suction may cause such a deficit.

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Infection lost may cause a fluid imbalance.

Infection causes fluid deficits in several ways:

1. Infection can increase metabolic demand, increasing insensible water loss.

When patients are not critically ill, they often mitigate this imbalance by increasing fluid intake.

When they have widespread infections or a self-care deficit, which may occur in the elderly, fluid intake may not be sufficient to

restore fluid balance

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2. Mediators are released as part of the immune response. lost may cause a fluid imbalance.

These mediators cause a loosening of the capillary tight junctions, resulting in the thirdspacing of fluids.

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3. Carbon dioxide production increases due to lost may cause a fluid imbalance.

increased metabolism.

To maintain pH balance, tachypnea may develop.

Although only a very small amount of fluid is lost daily through the respiratory tract, water loss may become clinically significant when the respiratory rate is greater than 35 breaths per minute.

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Renal Loss lost may cause a fluid imbalance.

The kidneys filter approximately 180 L per day.

However, urine output is only 1% to 2% of total blood volume filtered.

Reabsorption of fluid is influenced by a complex regulatory system that includes the actions of

aldosterone, angiotensin, and antidiuretic hormone (ADH).

A defect in any one of the regulatory functions can cause a disruption in renal fluid balance.

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Several endocrine disorders may disrupt the renal regulatory system.

Adrenal insufficiency, the absence of glucocorticoids and aldosterone, can cause a reduction in the absorption of sodium, thereby promoting water loss.

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Diabetes insipidus is a profound reduction in ADH, which reduces the amount of fluid reabsorbed at the distal convoluted tubule.

Water loss predominates in diabetes insipidus,and therefore volume imbalance is related to dehydration

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Serum osmolarity is predicted by sodium, glucose, and blood urea nitrogen.

’Normally, glucose does not influence the overall osmolarity.

However, in profound hyperglycemia, the influence of glucose increases greatly.

Serum osmolarity increases and is sensed by the osmoreceptors, thereby pulling fluids into the vascular space and initiating an osmotic diuresis.

Two conditions that pathologically increase glucose are diabetic ketoacidosis (DKA) and hyperglycemic, hyperosmolar, and nonketotic (HHNK) coma.

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Diuretic therapy is intended to treat fluid volume excess. urea nitrogen.

However, overadministration of diuretics may result in a fluid volume deficit.

It is important to recognize the immediate onset that diuretics can have when administered intravenously, initiated for the first time, or adjusted in dosage (see Table 30-5 for more information).

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Third-Spacing of Fluid urea nitrogen.

Third-spacing of fluid is the movement of fluid from

the vascular space to the interstitial space.

To create a movement of fluid between body compartments, there is an alteration in capillary permeability because of inflammation, ischemia, or injury.

Causes of third-spacing of fluids are numerous and include infection; systemic inflammatory response syndrome (SIRS), such as in pancreatitis; hypoalbuminemia, such as in liver failure; burns; intestinal obstruction; and surgery

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The amount of fluid lost depends on the degree of the pathophysiological alteration.

Regardless of cause, the fluid lost is not functioning to maintain vascular volume, and therefore a fluid volume deficit exists.

When fluid leaks out of the vascular space, daily weights can increase, paradoxically, despite intravascular volume depletion.

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MANAGEMENT: pathophysiological alteration. FLUID VOLUME REPLACEMENT

To correct a fluid volume deficit, it is necessary to treat the underlying cause and replace the lost fluid.

The main purposes of fluid administration include replacement of lost fluid, maintenance of fluid balance, and replacement of lost electrolytes.

Several types of fluids, which have different physiological effects, are available.

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Administration of fluids may occur using the gastrointestinal tract or an IV route.

When chronic replacement is required, such as in patients with long-term tube feeding, the gastrointestinal approach is used.

Enteral access is required when patients are unable to take fluids by mouth.

When rapid restoration of fluid balance is required, the IV route is preferred.

Occasionally, both routes are used.

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Maintenance Fluids gastrointestinal tract or an IV route.

Under normal conditions, the average healthy adult requires about 2.5 L/day.

This volume replaces fluids lost through the feces, the respiratory tract, sweating, and the urine

Patients who are unable to consume their usual intake of fluid are often prescribed IV maintenance fluids of 2 to 3 L/day.

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When determining the rate of administration gastrointestinal tract or an IV route.

of maintenance fluid, factors such as medical history (renal failure), age (young or old), confounding water excesses (congestive heart failure), and ongoing assessment parameters

(edema formation) must be considered.

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Replacement Fluids gastrointestinal tract or an IV route.

Critically ill patients are often unable to consume the

additional fluid required to replace the lost fluid.

In this case, IV administration beyond baseline maintenance fluids is required for homeostasis.

This is achieved by either administering a bolus of fluid or increasing the total daily fluid intake.

When fluid loss occurs acutely, the loss must

be replaced immediately to maintain tissue perfusion.

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The type of fluid given depends on the type of fluid lost. gastrointestinal tract or an IV route.

When whole blood is lost, such as in trauma or surgery, blood may be administered.

When intravascular volume is depleted, such as in diarrhea, isotonic solutions may be administered.

The rate of administration depends on the patient’s medical history and amount of volume lost.

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Crystalloids. gastrointestinal tract or an IV route. Crystalloid solutions are prepared with a specified balance of water and electrolytes. Box 30-11 provides a description of commonly used crystalloid solutions.

These fluids are described separately, but they are

most commonly used in combination.

Fluids are classified as hypotonic (osmolarity <250 mEq/L), isotonic (osmolarity approximately 310 mEq/L), or hypertonic (osmolarity >376 mEq/L).

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Dextrose solutions are given to provide free water and some calories to prevent protein catabolism.

The 5% solution contains 50 g of dextrose for every liter of fluid and provides approximately 170 calories per liter.

When pure dextrose solutions such as 5% dextrose in water (D5W) are administered, the dextrose is metabolized, resulting in the administration of free water.

When given intravenously, free water decreases the plasma osmolarity, thereby promoting the movement of water evenly into all body compartments.

Free water does not stay in the vascular space; therefore, pure dextrose solutions should not be used when intravascular replacement of fluids is required.

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Saline solutions are commonly used and are available in calories to prevent protein catabolism.

different strengths, such as 0.9% and 0.45%.

Normal saline, or 0.9% saline, is an isotonic solution.

Approximately one fourth of the fluid administered remains in the vascular space, and the remaining fluid moves into the extracellular space 1 hour after administration.

During critical illness, the amount that exits into the extracellular space can increase due to increased capillary permeability.

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Half-strength saline, in comparison, is a hypotonic solution.

Additional free water is administered with this solution, making it an ideal maintenance fluid.

Occasionally, half-strength saline is administered to replace fluids lost when there is concurrent hypernatremia.

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Saline solutions, such as 3% saline, are hypertonic and may be given for the treatment of symptomatic hyponatremia.

The hypertonicity pulls fluid from the extravascular space to the vascular space.

Hypertonic solutions should be administered only where patients may be closely monitored because fluid volume excess can develop rapidly.

Some studies have shown that hypertonic saline solutions, such as 3% or 7.5% saline, may be beneficial during resuscitation.

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Colloids. be given for the treatment of symptomatic hyponatremia.Colloids are high–molecular-weight substances and therefore do not cross the capillary membrane under normal conditions. Table 30-6 describes commonly prepared colloid solutions.

Albumin is the most abundant circulating protein in the body and accounts for 80% of the colloid oncotic pressure.

For therapeutic uses, albumin is prepared from donor plasma.

With albumin, there is no risk of bloodborne diseases, such as hepatitis or human immunodeficiency virus

(HIV) infection.

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Albumin is available in two concentrations, be given for the treatment of symptomatic hyponatremia.

5% and 25%, and both preparations contain some


The 5% solution is similar in osmolarity to plasma.

In contrast, the 25% solution is hypertonic, thereby pulling extravascular water into the vascular space.

Both preparations of albumin can cause the intravascular volume to expand beyond the volume of albumin infused because of the increased oncotic pressure generated.

Care must be taken when administering albumin to patients at high risk of volume overload.

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Use of albumin should also be limited in patients with profound capillary leak syndrome (e.g., in sepsis, acute respiratory distress syndrome, and pancreatitis).

Although albumin is a protein, it is inefficient and

expensive when used for malnutrition.

The starches dextran and hetastarch, which differ from each other only slightly, have an oncotic pressure similar to albumin.

Both substances are used to expand plasma volume by exerting an oncotic pressure and thereby pulling water from the extravascular space to the vascular space.

Hetastarch is metabolized by both the kidneys and liver.

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The diuresis that may occur with hetastarch is an osmotic diuresis and does not reflect an increase in effective renal circulatory volume.

Both dextran and hetastarch may cause coagulopathies; however, dextran has a more profound effect on coagulation.

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Fluid Volume Excess diuresis and does not reflect an increase in effective renal circulatory volume.

Fluid volume excess occurs when there is the retention of sodium, resulting in the reabsorption of water.

Electrolytes typically remain unchanged when there is an increase in total body water and electrolytes increase in parallel.

Many critically ill patients may have mixed disturbances with manifestations of the confounding compensatory mechanisms.

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Causes of fluid volume excess include overadministration of fluids, edematous disorder (e.g., congestive heart failure, kidney or liver failure), excessive sodium intake, and medications (e.g., steroids, desmopressin acetate).

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When the kidneys are functioning normally and regulating fluid balance, the body typically rids itself of excess fluid and fluid overload is not manifested clinically.

When the kidneys sense a decrease in effective circulatory volume, the compensatory mechanisms prevent the excretion of excess water, such as in congestive heart failure.

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Management of fluid volume excess is directed toward correction of the underlying disorder.

If this is not feasible, efforts are geared to prevention of pulmonary compromise by attempting to rid the body of the excess sodium and water.

In cases of volume overload, there is an increase in pulmonary hydrostatic pressure, which promotes movement of water into the alveoli, thereby impeding gas exchange.

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Sodium restriction reduces the amount of water reabsorption but does contribute to acute correction of volume overload.

Diuretics are the mainstay of treatment for acute resolution of fluid volume excess (see Table 30-5).

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MANAGEMENT OF ELECTROLYTE IMBALANCES but does contribute to acute correction of volume overload.

Electrolyte disorders commonly occur in critically ill

patients, typically in combination with other conditions.

Management of the underlying problem ensures longterm

restoration of balance.

However, acute management of electrolyte disorders is often required to maintain cellular integrity.

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Sodium but does contribute to acute correction of volume overload.

Sodium is the major extracellular cation.

It is a major predictor of serum osmolarity and controls movement of water.

Disorders of sodium are typically associated with

water disorders (Table 30-7).

Hyponatremia may be associated with volume excess, such as in edematous disorders (e.g., heart, kidney, or liver failure), or with volume deficit, such as when volume loss is exceeded by sodium loss (e.g., in gastrointestinal fluid, diuretic overuse, or adrenal insufficiency).

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Low sodium with euvolemia is manifested as the syndrome of inappropriate ADH secretion

Pseudohyponatremia may occur in association with hyperlipidemia and hypoproteinemia; the total body sodium remains unchanged, but the actual sodium measurement is altered

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Management of hyponatremia is aimed at correcting the inappropriate ADH secretion

underlying cause (see Table 30-7).

When the hyponatremia is associated with hypervolemia, diuretics may be beneficial.

When the disorder is associated with euvolemia, such as in SIADH, water restriction may be useful.

In conditions in which there is both sodium loss and water loss, administration of hypertonic saline at slow rates may help improve clinically significant hyponatremia.

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Hypernatremia may occur as an isolated condition inappropriate ADH secretion

when there is a loss of free water, which raises the sodium level.

Increased insensible loss of fluid, such as occurs in

sweating, hyperventilation, or fever, is the most common cause of this type of hypernatremia.

The fluid volume deficit associated with the hypernatremia depends almost entirely on the degree of insensible loss.

Endocrine disorders, such as hyperaldosteronism, or Cushing’s disease, can result in hypernatremia and are associated with total body water excess. Administration of hypertonic fluids, such as sodium bicarbonate, 3% saline, or albumin, may also cause hypernatremia

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Management of hypernatremia is primarily aimed atnrestoring fluid balance

Correcting the underlying cause of the increased sodium is also important.

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Potassium fluid balance

Potassium is the major intracellular ion.

Potassium plays a key role in neuromuscular functioning, and high or low levels may result in alterations in the cardiac rhythm.

Because of the narrow range of extracellular potassium

balance, renal function is essential to regulation of potassium.

In critically ill patients, disorders of potassium are

common and have numerous causes

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Hypokalemia is most commonly caused by an absolute fluid balance

deficiency in potassium.

Losses of potassium occur through the kidneys, gastrointestinal tract, sweat, and intracellular shifting.

Although relative deficiencies may occur, such as in metabolic alkalosis, they are rare compared with the absolute deficits.

Management of hypokalemia involves replacement

of depleted potassium to restore potassium balance.

It may be necessary to check the magnesium level in patients who do not respond to potassium replacement.

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Hyperkalemia is caused by reduced renal excretion, excessive administration of potassium replacements, transcellular shifts, an measurement error.

Patients with renal failure are at particular risk.

Dialysis is typically used to manage hyperkalemia in patients with ESRD.

Noncompliance with dialysis can certainly cause hyperkalemia and is a frequent reason for hospital admission.

Potassium replacement therapy, although performed frequently inliberation of the abundant intracellular potassium.

Evaluating trends and assessing the overall clinical picture prevents unnecessary treatment and therefore prevents hypokalemia.

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Calcium administration of potassium replacements, transcellular shifts, an measurement error.

Almost all of the calcium in the body is contained in the bone, and the remaining 1% is either bound to albumin (50% plasma calcium) or in an ionized form.

The primary function of calcium is promotion of the neuromuscular impulse.

Several clotting factors also depend on calcium.

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Hypocalcemia has numerous causes administration of potassium replacements, transcellular shifts, an measurement error.

Most hypocalcemia is a relative deficiency; causes include intracellular shifting, decreased circulating protein, and binding with fatty acids (pancreatitis).

The relative hypocalcemia that occurs with a massive transfusion of blood is common in the critical care setting.

The blood is mixed with citrate to prevent coagulation; when the blood is infused, the citrate binds to calcium, causing a relative calcium deficiency.

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Trisodium citrate used for anticoagulation administration of potassium replacements, transcellular shifts, an measurement error.

in CRRT also results in hypocalcemia.

Other causes of hypocalcemia include increased renal excretion (loop diuretics) or decreased absorption (malabsorption syndromes).

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Calcium is transported in its ionized form, provides administration of potassium replacements, transcellular shifts, an measurement error.

some of the structural components in bone, and is also bound to albumin.

A low albumin level can therefore be one cause of a low calcium level.

The calcium level should be corrected for the low albumin before consideration of calcium replacement.

Replacement of calcium is required to prevent complications of bleeding and decreased impulse transmission.

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Hypercalcemia, which is less common in the critical care setting, is most often caused by malignancy.

Treatment is supportive and involves administration of diuretics and IV fluids, sometimes simultaneously.

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Magnesium setting, is most often caused by malignancy.

About two thirds of the magnesium in the body is in the skeletal system, and the remaining one third is in the intracellular space.

About 1% circulates in the extracellular space.

Magnesium is a catalyst for hundreds of enzymatic reactions and plays a role in neurotransmission and cardiac contraction.

Magnesium is primarily excreted by the kidneys.

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Hypomagnesemia is caused by loss of magnesium through the gastrointestinal tract or (less commonly) the kidneys.

Alcoholism is a significant cause.

The etiological mechanism is not completely understood, but it is thought that decreased dietary intake due to malnutrition, decreased absorption, and increased gastrointestinal losses (due to periodic emesis) all play a role.

Several drugs may also cause hypomagnesemia, including loop diuretics, aminoglycosides, amphotericin B, cis-platinum, cyclosporine, and citrate.

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Magnesium is available in a variety of preparations, including 50%, 20%, or 10% solutions.

It is important to pay particular attention to how the replacement preparation is ordered; the replacement solution should be “dosed” in grams instead of milliliters.

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Phosphorus including 50%, 20%, or 10% solutions.

Phosphorus is the major intracellular anion.

The source of adenosine triphosphate (ATP), phosphorus is implicated in many life-sustaining processes, such as muscle contraction, neuromuscular impulse conduction, and the regulation of several intracellular and extracellular electrolyte balances.

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Hypophosphatemia may be caused by several metabolic disorders, including refeeding syndrome and alcoholism, intracellular shifting due to respiratory alkalosis, binding by medications, such as phosphate-binding magnesium containing antacids, and excessive excretion of phosphate, such as in diabetic ketoacidosis

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Refeeding syndrome occurs when the patient is fed, either enterally or parenterally, after some time of starvation.

During starvation, protein catabolism occurs, depleting all of the intracellular phosphorus.

When a large glucose load is administered, as occurs with refeeding, it is thought that the insulin response shifts the phosphorus intracellularly.

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Management of hypophosphatemia may be problematic, particularly for patients on a mechanical ventilator.

Contraction of all muscles, including the diaphragm, depends on ATP.

Replacement of phosphorus is indicated in critically ill patients to achieve adequate pulmonary function.

Once the critical illness abates, the hypophosphatemia typically resolves as well.

However, replacement with either sodium or potassium phosphate is indicated in the meantime.

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Hyperphosphatemia is commonly associated with renal failure due to reduced elimination of phosphorus.

Because of the inverse relationship with calcium, the high phosphorus may also be associated with hypocalcemia.

Administration of phosphate binders and calcium supplementation are indicated.