Fluid and Electrolyte Balance PDF

Fluid Compartments and Fluid Homeostasis In adults, body fluids make up between 55% and 65% of total body mass Body fluids are present in two main compartments: inside cells (2/3) + outside cells (1/3) Intracellular fluids = cytosol Extracellular fluid = interstitial fluid (80%) + bl...

Fluid Compartments and Fluid Homeostasis In adults, body fluids make up between 55% and 65% of total body mass Body fluids are present in two main compartments: inside cells (2/3) + outside cells (1/3) Intracellular fluids = cytosol Extracellular fluid = interstitial fluid (80%) + blood plasma (20%) Filtration, reabsorption, diffusion and osmosis allow continuous exchange of water and solutes among body fluid compartments The balance of inorganic compounds that dissociate into ions (electrolytes) is closely related to fluid balance The body gains water by ingestion and metabolic synthesis The body loses water via urination, perspiration, exhalation and in feces Elimination of excess body water occurs through urine production The amount of urinary salt loss is the main factor determining body fluid volume The two main solutes in urine are sodium ions (Na+) and chloride ions (Cl–) Wherever solutes go, water follows 3 major hormones control renal Na+ and Cl–: ○ Angiotensin II ○ Aldosterone ○ Atrial natriuretic peptide (ANP) The major hormone that regulates water loss is antidiuretic hormone (ADH) Summary of Factors That Maintain Body Water Balance Factor Mechanism Effect Thirst center in the Stimulates desire to drink fluids Water gained if thirst is hypothalamus quenched Angiotensin II Stimulates secretion of aldosterone Reduces loss of water in urine Aldosterone By promoting urinary reabsorption of Reduces loss of water in Na+ and Cl-, increases water urine reabsorption via osmosis Atrial natriuretic Promotes natriuresis, elevated urinary Increases loss of water in peptide (ANP) excretion of Na+ (and Cl-) accompanied urine by water Antidiuretic Promotes insertion of water-channel Reduces loss of water in hormone (ADH), proteins (aquaporin-2) into apical urine also known as membranes of principal cells in vasopressin collecting ducts of kidneys. As a result, water permeability of these cells increases and more water is reabsorbed Serum vs. Plasma Serum = plasma without clotting factors Plasma = liquid component of blood; has clotting factors Electrolyte Locations Outside the cell, sodium (Na+) and chloride ( Cl-) are most abundant Inside the cell, the most abundant is potassium (K+); other important intracellular electrolytes are magnesium (Mg2+) and phosphate (HPO4-2) Major Electrolytes Electrolyte Plasma Level ICF Level Functions mEq/L mEq/L Sodium (Na+) 136-142 10 Creates much of the osmotic pressure of ECF; the most abundant cation in ECF Essential for electrical activity of neurons and muscle cells Potassium (K+) 3.8-5.0 141 Creates much of the osmotic pressure in ICF; the most abundant cation in ICF Essential for electrical activity of neurons and muscles Calcium (Ca+2) 4.6-5.5 1 Most is found in bones and teeth Maintains normal excitability of neurons and muscle cells Essential for blood clotting Magnesium (Mg+2) 1.3-2.1 58 Most is found in bone More abundant in ICF than in ECF Essential for ATP production and activity of neurons and muscle cells Chloride (Cl-) 95-103 4 Most abundant anion in ECF; diffuses easily into and out of cells; helps regulate osmotic pressure Part of HCI in gastric juice Bicarbonate 28 10 Part of the bicarbonate buffer system (HCO3-) Phosphate 1.7-2.6 75 Most is found in bones and teeth (HPO4-2) Primarily an ICF anion Part of DNA, RNA, ATP, phospholipids Part of phosphate buffer system Sulfate (SO4-2) 1 2 Part of some amino acids and proteins Blood Electrolyte Imbalances Electrolyte Name & Causes Signs & Name and Signs & Symptoms Causes Symptoms Sodium Hyponatremia may be Muscular Hypernatremia Intense thirst, (Na+) due to decreased weakness; may occur with hypertension,, sodium intake; dizziness, dehydration, water edema, increased sodium loss headache, and deprivation, or agitation, and through vomiting, hypotension; excessive sodium convulsions diarrhea, aldosterone tachycardia in diet or deficiency, or taking and shock; intravenous fluids; certain diuretics; and mental causes excessive water intake confusion, hypertonicity of stupor, and ECF, which pulls coma water out of body cells into ECF, causing cellular dehydration Chloride Hypochloremia may be Muscle Hyperchloremia Lethargy, (Cl-) due to excessive spasms, may result from weakness, vomiting, metabolic dehydration due to metabolic overhydration, alkalosis, water loss or water acidosis, and aldosterone deficiency, shallow deprivation; rapid, deep CHF, and therapy with respirations, excessive chloride breathing certain diuretics such hypotension, intake; or severe as furosemide and tetany renal failure, hyperaldosteronis m, certain types of acidosis, and some drugs Potassium Hypokalemia may Muscle fatigue, Hyperkalemia may Irritability, (K+) result from excessive flaccid be due to nausea, loss due to vomiting or paralysis, excessive vomiting, diarrhea, decreased mental potassium intake, diarrhea, potassium intake, confusion, renal failure, muscular hyperaldosteronism, increased aldosterone weakness; kidney disease, and urine output, deficiency, can cause therapy with some shallow crushing injuries to death by diuretics respirations, body tissues, or inducing and changes in transfusion of ventricular electrocardiogr hemolyzed blood fibrillation am, including flattening of T wave Calcium Hypocalcemia may be Numbness and Hypercalcemia Lethargy, (Ca+2) due to increased tingling of may result from weakness, calcium loss, reduced fingers; hyperparathyroidis anorexia,  calcium intake, hyperactive m, some cancers, nausea, elevated phosphate reflexes, excessive intake of vomiting, levels, or muscle vitamin D, and polyuria, hypoparathyroidism cramps, tetany, Paget’s disease of itching, bone and bone pain, convulsions; depression, bone fractures; confusion, spasms of paresthesia, laryngeal stupor, and muscles that coma can cause death by asphyxiation Phosphate Hypophosphatemia Confusion, Hyperphosphatemi Anorexia, (HPO42-) may occur through seizures, a occurs when nausea, increased urinary coma, chest kidneys fail to vomiting, losses, decreased and muscle excrete excess muscular intestinal absorption, or pain, phosphate, as in weakness, increased utilization numbness and renal failure; can hyperactive tingling of also result from reflexes, fingers, increased intake of tetany, and decreased phosphates or tachycardia coordination, destruction of body memory loss, cells, which and lethargy releases phosphates into blood Magnesium Hypomagnesemia may Weakness, Hypermagnesemia Hypotension, (Mg2+) be due to inadequate irritability, occurs in renal muscular intake or excessive tetany, failure or due to weakness or loss in urine or feces; delirium, increased intake of paralysis, also occurs in convulsions, Mg2+, such as nausea, alcoholism, confusion, Mg2+ - containing vomiting, and malnutrition, diabetes anorexia, antacids; also altered mental mellitus, and diuretic nausea, occurs in functioning therapy paresthesia, aldosterone and cardiac deficiency and arrhythmias hypothyroidism Hypernatremia: excessive sodium in the extracellular fluid (ECF). This can happen by: Loss of water ○ Diarrhea ○ Insensible water loss ○ Water deprivation Gain of sodium ○ Diabetes insipidus ○ Heat stroke Nursing Management of Hypernatremia Management of a client with increased sodium and fluid deficit should include an assessment of these seven areas: 1. 24-hour I&O record 2. Urine-specific gravity >1.025 3. For thready pulses and flat neck veins 4. For tachycardia and tachypnea 5. Changes in sensorium 6. Check and compare daily weights 7. Skin turgor and mucous membranes Hyponatremia: occurs when serum sodium is less than 135 mEq/L; caused by excess water or an increase in sodium loss. Some situations when hyponatremia can occur include: Gastrointestinal suctioning Diarrhea Inadequate salt intake Fluid shift from ICF to ECF by hypertonic solutions, which leads to dilutional hyponatremia Diuretics Vomiting Signs and symptoms include: lethargy, headache, confusion, apprehension, seizures, coma Hyperkalemia causes muscle cramps → weakness → paralysis, drowsiness, drop in blood pressure, EKG changes, dysrhythmias, abdominal cramping, diarrhea, oliguria Nursing Management of Hyperkalemia Hypokalemia causes alkalosis, shallow respirations, irritability, confusion, weakness, arrhythmias, lethargy, thready pulse, and slows/decreases intestinal motility Nursing Management of Hypokalemia IV potassium replacement (no faster than 10 to 20 mEq/hr to prevent hyperkalemia and cardiac arrest) Raisins, prunes, bananas, squash, potatoes, tomatoes, and fruit Teach patients on diuretics to eat foods high in potassium Oral potassium replacement Hold KCL unless urine output is at least 0.5 mL/kg of body weight per hour Clinical Considerations of Water and Electrolyte Balance Body fluids are extracellular (intravascular or interstitial) and intracellular (within cells) Osmolality of intracellular fluid and extracellular fluids is about equal (cell membrane) this value is about 290 mOsm/kg water. The plasma osmolality is approximated by the formula: [𝐵𝑈𝑁] [𝐺𝑙𝑢𝑐𝑜𝑠𝑒] 2([Na] + [K]) plasma + 2.8 + 18 Where Na and K are in mEq/L, and blood urea nitrogen (BUN) and glucose concentrations are in mg/100 ml (mg/dL) Assessment of Hydration Status in People Aged 65 and Older Fluid Volume Deficit and Excess Your text notes the difference between isotonic fluid volume deficit (hypovolemia) and hypertonic fluid volume deficit (dehydration). Hypovolemia results in decreased perfusion and activation of the RAAS. It happens when both water and salts are lost in equal amounts. (Vomiting and diarrhea). Dehydration can also result in decreased perfusion but happens when more water is lost than salts. Sweating is the best example. Hypovolemia, Isotonic Dehydration Common causes: hemorrhage, vomiting, diarrhea, burns, diuretic therapy, fever Fluid Volume Deficit Types of FVD: isotonic fluid loss, hypertonic dehydration, and third spacing Isotonic Fluid Loss Happens when fluids and solutes are lost equally ○ Serum osmolarity remains normal Intracellular water is not disturbed Fluid loss is extracellular fluid ○ Can quickly lead to shock ○ Requires extracellular fluid replacement ○ Emphasis is on increasing vascular volume Fluid Volume Deficit Causes Isotonic dehydration ○ Inadequate intake of fluids and solutes ○ Fluid shifts between compartments ○ Excessive losses of isotonic body fluids Hypertonic dehydration ○ Conditions that increase fluid loss such as excessive perspiration, hyperventilation, ketoacidosis, prolonged fevers, diarrhea, early-staged renal failure, and diabetes insipidus Alterations in Fluid Volume Isotonic fluid volume deficit: decrease in the extracellular fluid, including circulating blood volume. It is caused by impaired intake, excessive losses of body fluids, osmotic diuresis, excessive sweating or when large areas of skin have been damaged, third-space losses. Manifestations include weight loss, hypovolemic shock, thirst, urine output decreased, arterial and venous volume decrease. Isotonic fluid volume excess: isotonic expansion of the extracellular fluid. It is caused by increased sodium intake, decrease in sodium and water elimination by the kidney, heart failure. Manifestations include increase in interstitial and vascular fluids, edema, puffy eyelids. Dehydration Nursing Care Plan Fluid Volume Excess Too much fluid going in with failure to eliminate. Sodium concentrations can be decreased, as well as the osmolality, because there is more water than sodium. The hematocrit will be reduced from the dilution of excess water Neurologic: changes in LOC, confusion, headache, seizures Respiratory: pulmonary congestion Cardiovascular: bounding pulse, increase in blood pressure and JVD, tachycardia, presence of S3 Gastrointestinal: anorexia, nausea Edema: dependent pitting edema Signs and Symptoms of Fluid Volume Imbalance Hypovolemia: poor skin turgor, dry mucous membrane, dry axilla, flat neck vein, tachycardia, hypotension, weight loss, sunken eyes Hypervolemia: shortness of breath at rest and exertion, hepatojugular reflex, ascites, pitting edema, weight gain Fluid Volume Excess - Hypervolemia Edema Clinical Signs of Overhydration Restlessness, tachycardia, tachypnea, chemosis, increased body weight, harsh lung sound or crackles on auscultation Cardiogenic Shock Special Example: Cirrhosis/Liver Failure Liver fails to produce enough albumin to maintain oncotic (osmotic) pressure in the plasma. Hydrostatic pressure exceeds osmotic pressure. Excess fluid in the tissues but decreased fluid in the vascular compartment. Signs of both excess and deficit. Third spacing, edema, ascites, plus hypovolemia Give extra IV albumin or hypertonic fluids to shift fluids back. Health Promotion Modifiable risk factors ○ Stress can increase cellular metabolism, blood glucose concentration, catecholamine levels ○ Stress can increase production of antidiuretic hormone (ADH) Promotes fluid retention, decreased urine output ○ Medications can contribute to fluid and electrolyte imbalance Heat-related illness ○ Limit outdoor activity during hottest part of the day ○ Take frequent breaks for rest and water ○ Drink water before beginning to feel thirsty ○ Wear lightweight clothes ○ Work or exercise with others when engaging in activity outside Nursing Assessment Observation and patient interview ○ Edema of lower extremities or hands and face ○ Flushed face, neck, arms ○ Dry, cracked lips ○ Dry mucous membranes, skin ○ Sunken eyes Nursing history ○ Current, past medical history ○ Medications ○ Functional, developmental, socioeconomic factors ○ Age ○ Lifestyle ○ Food and fluid intake, fluid output Physical examination ○ Skin ○ Oral cavity and mucous membranes ○ Eyes ○ Cardiovascular, respiratory systems ○ Neurologic, muscular status ○ Daily weights ○ Vital signs ○ Fluid intake and output Fluid volume deficit: output substantially exceeds intake Fluid volume excess: intake substantially exceeds output Diagnostic Tests Serum electrolytes Complete blood count ○ Hematocrit affected by changes in plasma volume Osmolality ○ Serum osmolality ○ Urine osmolality Urine specific gravity Independent Interventions Compare intake with output frequently Assess choice and types of fluids consumed, especially those with diuretic effect Weigh patient daily Engage patient in plan of care Provide patient education as indicated, especially regarding medication regimens and side effects Collaborative Interventions Education on appropriate use of electrolyte replacement fluids, salt tablets Oral replacements or initiation of IV therapy for significant fluid loss Electrolyte supplements Diuretics Pharmacologic Therapy Electrolyte correction depends on specific electrolyte, whether deficit or excess Hyperkalemia: Calcium, insulin, glucose, kayexalate Hypokalemia Hypernatremia Hyponatremia Remember, sodium is extracellular, potassium is intracellular Lifespan: Infants and Children Infants and children More vulnerable to fluid and electrolyte imbalances because of physiological differences ○ Infants lose more fluid through kidneys, which are less able to conserve water ○ Body surface area (BSA) proportionately greater, increasing insensible fluid loss ○ Percentage of body weight that is fluid varies with age Highest at birth, higher in premature infants ○ Infants, children 5% of body weight Circulatory overload ○ Full, bounding pulse ○ Distended neck, peripheral veins ○ Increased CVP ○ Cough, dyspnea, orthopnea ○ Moist crackles ○ Polyuria ○ Ascites ○ Peripheral edema or (if severe) anasarca ○ Decreased hematocrit and BUN ○ Cerebral edema  Heart failure Fluid Volume Excess Risk Factors Heart disease Kidney dysfunctions Diabetes with peripheral vascular disease Hypertension IV therapy Fluid Volume Excess Prevention Focus on disease states leading to overload Diuretics, antihypertensive medications to keep fluids in balance Weighing daily to identify early signs Careful intake of sodium Elevate lower extremities when sitting Collaborative Interventions Diagnostic tests ○ Serum electrolytes ○ Serum osmolality ○ Serum hematocrit and hemoglobin ○ Tests of renal and liver function may help to determine cause of FVE Pharmacologic therapy ○ Loop diuretics ○ Thiazide-type diuretics ○ Potassium-sparing diuretics Fluid management ○ Fluid intake may be restricted ○ Amount of fluid allowed prescribed by primary care provider ○ All fluid intake must be calculated Fluid at meals Fluid used to administer medications Fluid content of foods must be considered Dietary management ○ Sodium-restricted diet often prescribed for patients with FVE Fluid Volume Excess Lifespan considerations Infants and children FVE caused by overhydration ○ Newborns at greatest risk Symptoms ○ Change in behavior ○ Drowsiness Treatment  ○ Limiting intake ○ Use of diuretics in severe FVE Excess fluid associated with increased risk for acute kidney injury (AKI), mortality Older adults Most often result of heart failure or kidney disease Less common than dehydration Additional factors include use of antacids for gastric distress Fluid Volume Deficit and Dehydration Fluid volume deficit (FVD): decrease in intravascular, interstitial, and/or intracellular fluid Dehydration: loss of fluid alone ○ Often used interchangeably with FVD Fluid Volume Deficit and Dehydration: Pathophysiology FVD develops slowly or rapidly depending on type of fluid loss ○ Loss of extracellular fluid (ECF) volume → hypovolemia Loss of electrolytes along with fluid → isotonic fluid volume deficit ○ Deficiency may be extracellular or intracellular ○ Sodium may be normal, low, or elevated Isotonic dehydration: normal sodium level May result from vomiting, diarrhea, hemorrhage Hypotonic dehydration: proportionately more sodium loss than water loss May result from severe, prolonged vomiting and diarrhea; burns; renal disease Hypertonic dehydration: proportionately less sodium loss than water loss May result from end-stage renal disease (ESRD), diabetes insipidus, IV fluid or tube feedings with high electrolyte levels Third spacing ○ Fluid shifts from vascular space to other area Abdomen or bowel Ascites  Pleural or peritoneal space Interstitial tissues Trapped fluid = volume loss ○ Fluid unavailable to support normal physiologic processes Difficult to assess ○ May not be reflected in measurable data Third Spacing: loss of fluid into a space that cannot contribute to ICF/ECF equilibrium Signs and symptoms: urine output decreases, increased heart rate, decreased BP, decreased CVP, increased body weight, edema, I&O imbalance Causes: burns, ascites, peritonitis, bowel obstruction, massive bleeding into joint or body cavity Fluid Loss: Etiology Excessive fluid loss ○ Most common: excessive loss of gastrointestinal (GI) fluids Vomiting Diarrhea GI suctioning Intestinal fistulas Intestinal drainage ○ Other causes of fluid loss Diuretic therapy, renal disorders, endocrine disorders → excessive renal losses Heavy sweating → water and sodium losses Hemorrhage Chronic abuse of laxatives, enemas Inadequate intake ○ Lack of access to fluids ○ Inability to request or swallow fluids ○ Oral trauma ○ Altered thirst mechanisms ○ Excessive exercise during very hot weather without fluid replacement Burns ○ Huge loss of body fluids ○ Water and electrolytes, especially sodium ○ Fluids leak into interstitial spaces ○ Hypotonic dehydration in initial period after burn ○ High loss of ECF ○ Longer term: also loss of intracellular fluid (ICF) Risk Factors of Fluid Loss Inadequate intake ○ Lack of access to fluids  ○ Inability to request or swallow fluids ○ Oral trauma ○ Altered thirst mechanisms ○ Excessive exercise during very hot weather without fluid replacement Burns ○ Huge loss of body fluids Water and electrolytes, especially sodium ○ Fluids leak into interstitial spaces ○ Hypotonic dehydration in initial period after burn High loss of ECF ○ Longer term: also loss of intracellular fluid (ICF) Prevention of Fluid Loss FVD may occur in normal daily life as well as illness, burns, and so on ○ Sweating, especially in hot, humid weather or under heavy clothing in cold weather ○ Artificially heated indoor air ○ Altitudes >8200 feet ○ Very cold, dry environment for extended time Prevention involves drinking enough fluids to replace fluid lost to environmental factors ○ Electrolyte fluids in moderation, rather than just water ○ Encourage water consumption by younger children, older adults FVD Collaborative Interventions ➔ Diagnostic tests ◆ Serum electrolyte panel In severe, continuing dehydration complicated by electrolyte imbalance or acidosis Includes serum electrolytes, creatinine, glucose tests Elevated blood urea nitrogen (BUN), low serum bicarbonate help identify moderate, severe dehydration ◆ Urine specific gravity Useful in dehydrated adults, older children May not be useful in younger children ○ Cannot concentrate urine effectively ○ Rising specific gravity may not be seen in dehydration ➔ Clinical therapies ◆ Oral rehydration Safest, most effective treatment for FVD if patient is alert, can drink Mild fluid deficit: water alone For more severe fluid deficit: sports drink, ginger ale, Pedialyte, Rehydralite Replace fluids gradually, especially in older adults ◆ Intravenous fluids For severe deficit or when patient cannot ingest fluids Normal saline can be used but may lead to acid–base imbalance Lactated Ringer’s solution preferred 5% dextrose in water or half normal saline mix to treat total body water deficiency Fluid challenge to evaluate volume when urine output is low, cardiac or renal function is questionable Fluid Volume Deficit Lifespan Children and adolescents Sources of fluid loss ○ Low-birth-weight infants kept under radiant warmers ○ Higher body surface area (BSA), increased respiratory rate → more insensible fluid loss through skin, lungs ○ Increased risk for fever, which increases metabolic rate ○ More prone to vomiting, diarrhea ○ More likely to experience imbalance from exercise Larger BSA → more heat gain in hot environments, more heat lost in cold environments ○ Adrenal insufficiency ○ Accumulation of ECF in third space ○ Overuse of diuretics Especially adolescents with bulimia  Assessment ○ Mild dehydration Hard to detect in pediatric patients Irritability in infants Thirst in children Moderate dehydration ○ Lethargy and sleepiness ○ Restlessness and irritability ○ Decreased skin turgor ○ Dry mucous membranes ○ Increased pulse, normal or low BP ○ Seizure activity ○ Decreased or absent urinary output Lifespan: Geriatric Older adults Increased risk for rapid dehydration ○ Fewer intracellular reserves ○ Blunted thirst perception ○ Altered hormone response Increased risk for imbalance ○ Changes in mentation, cognition ○ Adverse effects of medications Lack of free access to fluids Voluntary fluid restriction Medications may lead to dehydration Manifestations may be hard to recognize ○ Possible early sign: change in mental status, memory, or attention ○ Skin turgor less reliable as indicator More effective: assessing turgor over sternum, on inner aspect of thigh Indications of dehydration ○ Dry mucous membranes ○ Tongue furrows ○ Chronic dehydration Manifestations of chronic dehydration ○ Itchy skin ○ Brittle hair ○ Loss of thirst reflex Nursing Process Assessment Observation and patient interview ○ Risk factors ○ Medications ○ Renal or endocrine disease ○ Precipitating factors ○ Access to fluids ○ Recent illness Onset, duration of symptoms Physical examination ○ Weight ○ Vital signs ○ Peripheral pulses ○ Capillary refill ○ Jugular vein distention (JVD) ○ Skin color, temperature, turgor ○ Level of consciousness (LOC), mentation ○ Urine output Planning Goals for adults may include that patient will ○ Achieve fluid and electrolyte balance ○ Drink 1500 mL fluid/day ○ Relate need to replace fluids lost during exercise with sports drinks ○ Return to normal hydration status and not develop hypovolemic shock Goals for children may include that parents will ○ Relate strategies to prevent dehydration ○ Describe appropriate home management of fluid replacement for diarrhea, vomiting ○ Describe when to seek healthcare Implementation Record intake and output (I&O) accurately ○ Hourly I&O may occasionally be indicated Weigh patient daily with same scale and in same or similar clothing Take vital signs, central venous pressure (CVP), peripheral pulse volume at least every 4 hours Administer, monitor intake of fluids as prescribed Administer IV fluid using electronic infusion pump Monitor lab values ○ Electrolytes, BUN, creatinine, osmolality, urine specific gravity Monitor for changes in LOC, mental status Reposition patient every 2 hours Institute safety precautions to avoid falls Teach patient, family  ○ How to reduce orthostatic hypotension ○ Importance of maintaining adequate fluid intake ○ How to prevent fluid deficit Teach parents not to give diet beverages for oral rehydration Encourage parents to keep on hand an oral rehydration solution to use when child has diarrhea Evaluation Expected outcomes may include ○ Patient has water, electrolytes that are balanced in intracellular and extracellular compartments as measured by serum electrolytes, hematocrit, assessment findings ○ Patient’s urinary output is within normal limits ○ Patient has adequate fluid intake ○ Patient’s vital signs are within normal limits If outcomes are not met ○ More aggressive intervention is needed