Stressors Affecting Fluid & Electrolyte Balance

Stressors AffectingFluid & Electrolyte Balance NUR 101 FALL 2008 LECTURE # 15 & #16 K. Burger, MSEd, MSN, RN, CNE

Body Fluids • Water= most important nutrient for life. • Water= primary body fluid. Adult weight is 55-60% water. • Loss of 10% body fluid = 8% weight loss SERIOUS • Loss of 20% body fluid = 15% weight loss FATAL • Fluid gained each day should = fluid lost each day (2 -3L/day average) • What is the minimum output per hour necessary to maintain renal function? 30ml/hr

Functions of Body Fluid • Medium for transport • Needed for cellular metabolism • Solvent for electrolytes and other constituents • Helps maintain body temperature • Helps digestion and elimination • Acts as a lubricant

Gain Fluid intake 1500ml Food intake 1000ml Oxidation of nutrients 300ml(10ml of H20 per 100 Kcal) Loss “Sensible”Can be seen.Urine 1500mlSweat 100ml “Insensible”Not visible.Skin (evaporation) 500mlLungs 400mlFeces 200ml Mechanisms of Fluid Gain and Loss

Regulation of Fluids • Hypothalmus –thirst receptors (osmoreceptors) continuosly monitor serum osmolarity (concentration). If it rises, thirst mechanism is triggered.+Vasopressin (AKA ADH )– increasing H20 reabsorption • Pituitary regulation- posterior pituitary releases ADH (antidiuretic hormone) in response to increasing serum osmolarity. Causes renal tubules to retain H20. • Thirst is a late sign of water deficit

Regulation of Fluids (continued ) • Renal regulation- Nephron receptors sense decreased pressure (low osmolarity) and kidney secretes RENIN. Renin – Angiotensin I – Angiotensin II • Angiotensin II causes Na and H20 retention by kidneys AND….. • Stimulates Adrenal Cortex to secrete Aldosterone which causes kidneys to excrete K and retain Na and H20.

Consider This…. • The Geriatric Client-normal physiological aging results in decreased thirst mechanism decreased # of sweat glands decreased renal function-there also may be decreased mobility and/or cognitive function which impacts their ability to get adequate fluid intake.

Variations in Body Fluids • Elderly: Have lower % of total body fluid than younger adults • Women: Have lower % total body fluid than men • WHY DO YOU THINK THIS IS ????? Muscle tissue has more H20 content THAN adipose tissue

Intracellular fluid (ICF) Fluid inside the cell Most (2/3) of the body’s H20 is in the ICF. Extracellular Fluid (ECF) Fluid outside the cell. 1/3 of body’s H20 More prone to loss 3 types: Interstitial- fluid around/between cells Intravascular- (plasma) fluid in blood vessels Transcellular –CSF, Synovial fluid etc Fluid Compartments

Consider this…. • Age variations exist in regards to H20 content of fluid compartments • Infants =60% of H20 is found in ECF40% of H20 is found in ICF • What might this mean in regards to fluid loss for an infant? Reverse of adults! Infant MORE PRONE to fluid LOSS!

Fluid Balance • Dynamic process • Balance between body fluids and electrolytes • Attraction between ions (electrolytes) and water (fluids) causes fluids to move across membranes and leave their compartments.

Solvent (H20) Movement • Cell membranes are semipermeable allowing water to pass through • Osmosis- major way fluids transported Water shifts from low solute concentration to high solute concentration to reach homeostasis (balance).

Osmolarity • Concentration of particles in solution • The greater the concentration (Osmolarity) of a solution, the greater the pulling force (Osmotic pressure) • Normal serum (blood) osmolarity = 280-295 mOSM/kg • A solution that has HIGH osmolarity is one that is > serum osmolarity = HYPERTONIC solution • A solution that has LOW osmolarity is one that is < serum osmolarity = HYPOTONIC solution • A solution that has equal osmolarity as serum = ISOTONIC solution

Hypertonic Fluids • Hypertonic fluids have a higher concentration of particles (high osmolality) than ICF • This higher osmotic pressure shifts fluid from the cells into the ECF • Therefore Cells placed in a hypertonic solution will shrink

Hypertonic Fluids • Used to temporarily treat hypovolemia • Used to expand vascular volume • Fosters normal BP and good urinary output(often used post operatively) • Monitor for hypervolemia !Not used for renal or cardiac disease. THINK – Why not? • D5% 0.45% NS • D5% NS • D5% LR Pulmonary Edema

Hypotonic Fluids • Hypotonic fluids have less concentration of particles (low osmolality) than ICF • This low osmotic pressure shifts fluid from ECF into cells • Cells placed in a hypotonic solution will swell

Hypotonic Fluids • Used to “dilute” plasma particularly in hypernatremia • Treats cellular dehydration • Do not use for pts with increased ICP risk or third spacing risk • 0.45%NS • 0.33%NS

Isotonic Fluid • Isotonic fluids have the same concentration of particles (osmolality) as ICF (275-295 mOsm/L) • Osmotic pressure is therefore the same inside & outside the cells • Cells neither shrink nor swell in an isotonic solution, they stay the same

Isotonic Fluid • Expands both intracellular and extracellular volume • Used commonly for: excessive vomiting,diarrhea • 0.9% Normal saline • D5W • Ringer’s Lactate

Other Osmotic Factors • ALBUMIN ( a serum protein ) • Albumin in the serum has osmotic properties called colloid pressure • Albumin pulls H20 from the interstitial compartments into the intravascular compartments (serum). Helps to maintain BP. • Persons with low serum albumin levels tend to retain fluid in their interstitial layers.What abnormal assessments might you find in the client with low serum albumin levels? Edema, hypotension

Hmmm……. • What type of IV fluid(hypotonic – isotonic – hypertonic)might be of benefit to this client with low albumin levels?

Consider this…. • When tissue injury occurs, proteins pathologically leak from the intravascular space into the intersititial space.Termed: Third spacing • This explains __________ as a sign of the inflammatory process. EDEMA

Solute Movement - Diffusion • Movement of solutes from high concentration to low concentration • It is a PASSIVE movement DOWN the concentration gradiant. (requires no energy) • Many body processes use diffusion. Example: O2 and CO2 exchange • Rate is affected by: concentration gradiant, permeability-surface area-thickness of membranes, and size of particles. (Fick’s Law)

Solute Movement –other mechanisms • Active transport- requires energy (ATP) to move from low concentration to high concentration (uphill)Example: Na / K pump • May be enhanced by carrier molecules with binding sites on cell membraneExample: Glucose (Insulin promotes the insertion of binding sites for Glucose on cell membranes).

Filtration • Solvent AND solute movement • Passage from an area of High Pressure to an area of Low Pressure Termed: Hydrostatic Pressure • Example:Arterioles have higher pressure than ICFFluid, oxygen and nutrients move into cellsVenules have lower pressure than ICFFluid, carbon dioxide and wastes move out of cells

Fluid volume deficit FVD (Hypovolemia) • Loss of both H20 and electrolytes from ECF. • Causes include:Increased output, Hemorrhage, vomiting, diarrhea, burns, OR • Fluid shift out of vascular space ( “third spacing” ) into interstitial spaces

Dehydration • Isotonic dehydration = H20 & electrolyte loss in equal amounts; diarrhea and vomiting • Hypertonic dehydration = H20 loss greater than electrolyte loss; excessive perspiration, diabetes insipidus

AssessmentFVD - Hypovolemia Cardiovascular: • Diminished peripheral pulses; quality 1+(thready) • Decreased BP & orthostatic hypotension • Increased HR • Flat neck & hand veins in dependent position • Elevated Hematocrit (Hct) Gastrointestinal: • Thirst • Decreased motility; diminished bowel sounds, possible constipation

Neuromuscular: Decreased CNS activity (lethargy to coma) Possible fever Skeletal muscle weakness Hyperactive DTR Renal: Decreased output Increased spec grav of urine Weight loss Hypernatremia Integumentary: Dry mouth & skin Poor turgor (tenting) Pitting edema Sunken eyeballs Respiratory: Increased rate and depth Assessment FVD – Hypovolemia (continued)

Nursing Diagnosis - FVD • Deficient Fluid VolumeR/T loss of GI Fluids via vomitingAEB elevated Hct, dry mucous membranes, decreased output, thirst

Planning - FVD • Client will demonstrate fluid balance aeb moist mucous membranes, balanced I & O measurements, Hct WNL, by ….

Interventions for FVD - Hypovolemia • Prevent further fluid loss • Oral rehydration therapy • IV therapy • Medications; antiemetics, antidiarrheals • Monitor CV, Resp, Renal, GI status • Monitor electrolytes – possible supplement rx • MONITOR WEIGHT and I & O

NCLEX Practice Intravenous fluids are ordered for your client who is experiencing diarrhea and vomiting for the past 2 days. Which IV solution would the nurse expect to see prescribed? • D5NS • 0.45%NS • D51/2NS • RL

Fluid Volume ExcessFVE - Hypervolemia • Fluid overload is an excess of body fluid - overhydration • Excess fluid volume in the intravascular area-hypervolemia • Excess fluid volume in interstitial spaces edema

Fluid Volume Excess • Causes: • Increased Na/H2O retention • Excessive intake of Na (PO or IV) • Excessive intake of H2O ( PO or IV)(Water intoxication) • Syndrome of inappropriate antidiuretic hormone (SIADH) • Renal failure, congestive heart failure

CV:Elevated pulse; 4+ bounding, elevated BP, distended neck & hand veins, ventricular gallop (S3)Hyponatremia Resp:Dyspnea, Moist Crackles,Tachypnea Integumentary:Periorbital edemaPitting or Non-pitting edema GI: Increased motilityStomach crampsNausea & Vomiting Renal: Weight gain Decreased spec grav of urine Neuromuscular:Altered LOC, headache, skeletal muscle twitching AssessmentFVE - Hypervolemia

Nursing Diagnosis - FVE Fluid volume excess R/T excessive H20 intake AEB confusion, headache, muscle twitching, abdominal cramps, elevated BP and HR, hyponatremia.

Planning - FVE • Client will demonstrate fluid balance by balanced I & O measurements, Serum Na WNL, etc. by ….

Interventions FVE - Hypervolemia • Restore normal fluid balance, prevent further overload • Drug therapy; diuretics • Diet therapy; decrease Na & fluids • Monitor intake and output (I & O) • Monitor weights • Monitor electrolytes • Monitor CV, Resp, Renal systems

Clinical Application You have been assigned to care for an 80y.o. client admitted with hypernatremia that has an IV infusing 0.45% NS @ 100ml/hr via pump and an indwelling urinary catheter. At 11am you assess an output in the urinary drainage bag of 150ml dk amber urine. You also notice that the client is SOB while speaking on the phone to her daughter. • What do you think is happening?? • What will you do??

SUMMARY Want more Information???CHECK OUT THE WEBLINKS For Chapter 41 on EVOLVE

Electrolytes • Work with fluids to keep the body healthy and in balance • They are solutes that are found in various concentrations and measured in terms of milliequivalent (mEq) units • Can be negatively charged (anions) or positively charged (cations) • For homeostasis body needs: Total body ANIONS = Total body CATIONS

Cations Positively charged Sodium Na+ Potassium K+ Calcium Ca++ Magnesium Mg++ Anions Negatively charged Chloride Cl- Phosphate PO4- Bicarbonate HCO3- Electrolytes

Electrolyte Functions • Regulate water distribution • Muscle contraction • Nerve impulse transmission • Blood clotting • Regulate enzyme reactions (ATP) • Regulate acid-base balance

Sodium Na+ • 135-145mEq/L • Major Cation • Chief electrolyte of the ECF • Regulates volume of body fluids • Needed for nerve impulse & muscle fiber transmission (Na/K pump) • Regulated by kidneys/ hormones

Hmmm… Hyper and Hypo Natremia are the most common electrolyte disturbances. Why do you think that is? It is most abundant in the EXTRACELLULAR FLUID and therefore more prone to fluctuation.

Hyponatremia • Serum Na+ <135mEq/L • Results from excess of water or loss of Na+ • Water shifts from ECF into cells • S/S: abd cramps, confusion, N/V, H/A, pitting edema over sternum • Tx: Diet/IV therapy/fluid restrictions

Lets think about …Hyponatremia • What are some medical conditions that may cause a dilutional hyponatremia?CHFRenal FailureSIADH ( Cancer, pituitary trauma )Addisons Disease ( hypoaldosteronism & Na loss ) • What are some conditions that might cause actual loss of sodium from the body?GI losses – nasogastric suctioning, vomiting, diarrheaCertain diuretic therapies • Permanent neurological damage can occur when serum Na levels fall below 110 mEq/L. Why?Hypotonic environment swells cells, increasing ICP – brain damage

Hypernatremia • Serum Na+> 145mEq/L • Results from Na+ gained in excess of H2O OR Water is lost in excess of Na+ • Water shifts from cells to ECF • S/S: thirst, dry mucous membranes & lips, oliguria, increased temp & pulse,flushed skin,confusion • Tx: IV therapy/diet

Let’s think about….Hypernatremia • What are some medical conditions that may cause elevated serum Na?Renal failureDiabetes InsipidusDiabetes Mellitus ( hyperglycemic dehydration)Cushings syndrome (hyperaldosteronism) • What are some other patient populations at risk for hypernatremia?Elderly ( decreased thirst mechanism )Patient’s receiving:-tube feedings-corticosteroid drugs-certain diuretic therapies • Seizures, coma, death my result if hypernatremia is left untreated. Why?Cells loose fluid into the ECF causing irreversible cell damage.

Stressors Affecting Fluid & Electrolyte Balance