به نام خداوند جان و خرد

به نام خداوند جان و خرد به نام خداوند جان و خرد کز این برتر اندیشه بر نگذرد کز این برتر اندیشه بر نگذرد

History • Dialysis is a Greek word meaning "loosening from something else". • Dialysis is referred to as "selective diffusion”. • Diffusion is the movement of material from higher concentration to lower concentration through a given membrane • Thomas Graham, Chairman of Chemistry at University College, London, first discovered this idea of selective diffusion

Dialysate • A chemical bath used in dialysis to draw fluids and toxins out of the bloodstream and supply electrolytes and other chemicals to the bloodstream.

Components of Dialysis Prescription • Choosing the type of dialyzer • Establishing blood & dialysate flow • Prescribing the time for dialysis procedure • Prescribing the dialysate composition • Determining the frequency of the dialysis procedure • Determining the intensity of anticoagulation of the extracorporeal circuit

Comparison of Dialyzers KoAurea = Urea mass transfer coefficient

Reasons to Use High-Efficiency Dialyzers

Lack of complement activation and early neutropenia during hemodialysis should serve as useful indices of biocompatible membrane . Cuprophan < Cellulose acetate < Hemophan < Polysulfone

The apparent advantage of biocompatible dialysis membranes has led to our using them routinely in patients with ARF.

Establishing blood & dialysate flow • Blood flow: • ~ 3 × weight for the initial treatment, especially when the predialysis SUN>130 mg/dl • In chronic dialysis patients minimum blood flow is~ 4 × weight,range 300 – 500 ml/min • Dialysate flow: • 500 – 800 ml/min

Prescribing the time for dialysis procedure • 2 hours for the first session • 3 hours for the second session, if predialysis SUN is less than 100 mg/dl • Third & subsequent dialysis sessions can often be up to 6 hours in length • Disequilibrium syndrome: • Nausea, vomiting, restlessness, headache, seizures, obtundation, coma

Composition of HD concentrate

Dialysate Sodium • Low Na dialysate • High Na dialysate • Stability of plasma osmolality • Improve tolerance to HD Increasing Na from 130 to 136 mEq/L : reducing cramps during dialysis Dialysate Na between 139 to 144 mEq/L: fewer headaches ,less cramping ,nausea and vomiting • Weight gain and poor blood control • ( Henrich et al: modest weigh gain were not associated with increases in BP or sign of volume overload)

Dialysate Sodium • Na Modeling A high dialysate Na concentration is used initially with a progressive reduction toward isotonic or even hypotonic levels by the end of HD (Dumler et al,1979: 50% decrease in cramping episodes) (Raja et al,1983 :no difference in hypotensive episodes) (Daugirdas et al,1985: no difference in hypotensive episodes or cramps) (Acchiardo et al,1991: 50% decrease in hypotensive and cramping episodes) (Sang et al ,1997: Decrease in hypotensive and cramping episodes but only in 22% of patients)

Dialysate Buffer • Acetate: in the early 1960s became the standard dialysate buffer used to • correct uremic acidosis • offset the diffusive losses of bicarbonate during HD In the mid 1980s some reported the linking between acetate and cardiovascular instability and hypotension during HD • Bicarbonate: emerged the buffer of choice

Bicarbonate buffer • Has become the standard base in most chronic dialysis center • Require a specifically designed system that mixes a bicarbonate and an acid (lactic or acetic acid) and all the Ca and Mg • PH of the final solution 7.0 to 7.4 and the final concentration of bicarbonate is 33 to 38mmol/L

Bicarbonate buffer Potential complications: • Microbial contamination • (decreases by short storage time, filtration,..) • Hypoxemia • (high concentration of bicarbonate) • Acute metabolic alkalosis • (mental confusion, lethargy, weakness and cramps)

Dialysis Solution BicarbonateConcentration • Excessive correction of severe metabolic acidosis (HCO3 <10 meq/l) can have adverse consequences, including paradoxical acidification of the CSF & an increase in the tissue production rate of lactic acid. • Initial therapy should aim for only partial correction of the plasma HCO3 level. ( postdialysisHCO3 = 15 - 20 )

Dialysis Solution BicarbonateConcentration • If the predialysis plasma bicarbonate level is >= 28 meq/l or if the patient has respiratory alkalosis dialysis solution with lower bicarbonate level should be used (e.g., 20 - 28 meq/l, depending on the degree of alkalosis).

Concentration of Dialysate Components Used in HD

Dialysis Solution Sodium Level • Predialysis serum sodium >=130meq/l: • Dialysis Solution Sodium Level = 140 + (140 - Predialysis serum sodium value) 140 + (140 - 130) = 140 +10 = 150 • Predialysis serum sodium <130meq/l: • Dialysis Solution Sodium Level no higher than 15 - 20 meq/l above the plasma level

Dialysis Solution Sodium Level • Hypernatremia • Whenever dialysis Solution Sodium Level is more than 3 - 5 meq/l lower than the plasma value, three complications of dialysis occur with increased frequency: • Hypotension • Muscle cramps • Cerebral edema & exacerbating the disequilibrium syndrome

Dialysis Solution Potassium Level *Dialysate K level in our country = 1 , 2 , 3

Dialysis Solution Potassium Level • Potassium rebound: marked rebound increase in the serum K level within1 - 5 hours after dialysis. (approximately 30%) • Hemodialysis can remove 25 to 50 mEq of K per hour, with variability based upon the initial serum: • K concentration • Dialyzer • Blood flood rate • K concentration of the dialysate.

Dialysis potassium The most efficient way to remove excess K stores: 2 - 3 hr periods of dialysis separated by several hours

Prevention of Hyperkalemia • Minimizing episodes of fasting which, in part via the reduction in endogenous insulin release, results in potassium movement out of the cells. • In one report, fasting for 18 hours led to a mean 0.58 meq/L raise in the plasma potassium concentration. • Thus, patients with ESRD undergoing electivesurgery should receive parenteral glucose containing solutions when fasting overnight..

Calcium • Calcium plays a role both in myocardial contractility and in peripheral vascular resistance. Therefore, an increase in dialysate calcium concentration may be useful in cardiac compromised hypotension-prone patients.

Dialysate Calcium • Aim: net flux of Ca into the patient • Dialysate Ca concentration of 3.5mEq/L(1.75mmol/L) is widely used • The dialysate Ca concentration should be individualized • Patients treated withthe dialysate Ca concentration <1.5 mmol/L the iPTH levels must be remain in acceptable range

Dialysis Solution Calcium Levels Routine use of 2.5meq/l calcium dialysate is conceptually inappropriate in the acute setting, where a decline in the ionized calcium concentration is usually undesirable.

HD in ARF • More intense delivered doses of dialysis appears to principally benefit patients with ARF and illnesses of intermediate severity. • Patients at either extremes of illness (severely ill or not very ill) have much less survival benefit with intense intermittent hemodialysis regimens.

HD in ARF CAN DIALYSIS DELAY RECOVERY OF RENAL FUNCTION? • There is at least theoretical concern that dialysis might have detrimental effects on renal function. Three factors may be important in this regard: • a reduction in urine output • induction of hypotension • complement activation resulting from a blood-dialysis membrane interaction.

Indications For Heparin-Free dialysis • Pericaditis(tight heparin acceptable if bleeding risk deemed low) • Recent surgery, with bleeding complications or risk. Especially: • Vascular & cardiac surgery (within 7 days) • Eye surgery (retinal & cataract) • Renal transplant • Brain surgery (within 14 days) • Coagulopathy • Thrombocytopenia • ICH • Active bleeding • Routine use for dialysis of acutely ill patients by many centers

Ultrafiltration Orders • In ARF even patients who are quite edematous & in pulmonary edema, rarely need removal of more than 4 L of fluid during initial session.

Dry Weight • The lowest weight a patient can tolerate without the development of signs or symptoms of intravascular hypovolemia. • Estimating dry Weight: Liters of actual body water = 142 × liters of NTBW = 142 × (60% × 60) = 38.72 Predialysis serum sodium 132 38.72 – 36 = 2.72 lit NTBW= Normal Total Body Water

No consensus exists concerning the optimal timing for the initiation of dialysis in patients with ARF . Indications include the following : • Refractory fluid overload • Hyperkalemia (plasma potassium concentration >6.5 meq/L) or rapidly rising potassium levels • Metabolic acidosis (pH < 7.1) • Azotemia (BUN > 80 to 100 mg/ dl)

به نام خداوند جان و خرد

به نام خداوند جان و خرد

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In the name of God