Handout Medical-surgical Nursing Fluid And Electrolyte

Fluid and Electrolytes

Homeostasis • •

State of equilibrium in internal environment of body, naturally maintained by adaptive responses that promote healthy survival Body fluids and electrolytes play an important role

Water Content of the Body

• • •

Accounts for 60% of body weight in adult 70-80% of body weight in infant Varies with gender, body mass, and age

Compartments • • • • •

Intracellular fluid (ICF) Extracellular fluid (ECF) Intravascular (plasma) Interstitial Transcellular

Intracellular Fluid (ICF) • • •

Fluid located within cells 42% of body weight Most prevalent cation is potassium (K+)

•

Most prevalent anion is phosphate (PO4-)

Extracellular Fluid (ECF) • • • • • • •

Fluid spaces between cells (interstitial fluid) and the plasma space Interstitial Most prevalent anion is chloride (Cl-) Most prevalent cation is sodium (Na+) Expands and contracts 2/3 of ECF in interstitium Extracellular Fluid (ECF)

Intravascular (IV) • • •

Within vascular space Measured with blood tests 1/3 of ECF

Transcellular Fluid • • •

Small but important fluid compartment Approximately 1L Includes fluid in

   

Cerebrospinal fluid Gastrointestinal (GI) tract Pleural spaces Synovial spaces

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Peritoneal fluid spaces

Mechanisms Controlling Fluid and Electrolyte Movement

     

Diffusion Facilitated diffusion Active transport Osmosis Hydrostatic pressure Oncotic pressure

Diffusion • • •

Movement of molecules from an area of high concentration to low concentration Occurs in liquids, solids, and gases Membrane separating two areas must be permeable to substance for diffusion to occur

Facilitated Diffusion

• •

• • • •

Very similar to diffusion Specific carrier molecules involved to accelerate diffusion Active Transport Process in which molecules move against concentration gradient Example: sodium-potassium pump ATP is energy source

Osmosis

• • •

Movement of water between two compartments by a membrane permeable to water but not to a solute Water moves from area of low solute concentration to area of high solute concentration Requires no energy

Osmotic Pressure

• • •

Amount of pressure required to stop osmotic flow of water Water will move from less concentrated to more concentrated side Determined by concentration of solutes in solution

Hydrostatic Pressure

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Force within a fluid compartment

•

Major force that pushes water out of vascular system at capillary level

Oncotic Pressure • •

Osmotic pressure exerted by colloids in solution Protein is major colloid in vascular system

Fluid Movement in Capillaries

•

Amount and direction of movement determined by    

Capillary hydrostatic pressure Plasma oncotic pressure Interstitial hydrostatic pressure Interstitial oncotic pressure

Fluid Shifts •

Plasma   

to interstitial fluid shift results in edema Elevation of hydrostatic pressure Decrease in plasma oncotic pressure Elevation of interstitial oncotic pressure

Fluid Shifts •

• •

Interstitial fluid to plasma Fluid drawn into plasma space whenever there is increase in plasma osmotic or oncotic pressure Wearing of compression stockings or hose is a therapeutic action on this effect

Fluid Movement between Extracellular and Intracellular

• •

Water deficit (increased ECF) is associated with symptoms that result from cell shrinkage as water is pulled into vascular system Water excess (decreased ECF) develops from gain or retention of excess water

Fluid Spacing • •

•

First spacing  Normal distribution of fluid in ICF and ECF Second spacing  Abnormal accumulation of interstitial fluid Third spacing  Fluid accumulation in part of body where it is not easily exchanged with ECF

Electrolytes •

Cations (+) and anions (-) are paired

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Most powerful cation is H+

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If one electrolyte is disturbed, others are likely disturbed

Regulation of Water Balance

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      

Hypothalamic regulation Pituitary regulation Adrenal cortical regulation Renal regulation Cardiac regulation Gastrointestinal regulation Insensible water loss

Hypothalamic Regulation • • •

Osmoreceptors in hypothalamus sense fluid deficit or increase in plasma osmolality Stimulates thirst and antidiuretic hormone (ADH) release Result in increased free water and decreased plasma osmolarity

Pituitary Regulation • •

Under control of hypothalamus, posterior pituitary releases ADH Stress, nausea, nicotine, and morphine also stimulate ADH release

Adrenal Cortical Regulation •

•

Adrenal cortex releases hormones to regulate both water and electrolytes  Glucocorticoids  Mineralcorticoids Aldosterone is a mineralocorticoid with potent sodium-retaining and potassium excreting capability  Factors Affecting Aldosterone Secretion  Effects of Stress on F&E Balance

Renal Regulation • • • •

Kidneys are primary organs for regulating fluid and electrolyte balance Selective reabsorption of water and electrolytes Excretion of electrolytes occurs Renal tubules are sites of action of ADH and aldosterone

Cardiac Regulation • •

Atrial natriuretic factor (ANF) is released by the cardiac atria in response to increased atrial pressure ANF causes vasodilation and increased urinary excretion of sodium and water

Gastrointestinal Regulation • •

Gastrointestinal tract accounts for most of the water intake Small amounts of water are eliminated by GI tract in feces

Insensible Water Loss • • •

Invisible vaporization from lungs and skin Approximately 900 ml per day is lost No electrolytes are lost with insensible water loss



Excessive sweating, not insensible loss, leads to loss of water and electrolytes

[Sodium] • •

Imbalances typically associated with parallel changes in osmolality Plays a major role in  ECF volume and concentration  Generation and transmission of nerve impulses  Acid-base balance

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Hypernatremia • •

•

Elevated serum sodium occurring with water loss or sodium gain Causes hyperosmolality leading to cellular dehydration Primary protection is thirst from hypothalamus

Differential Assessment of ECF Volume 

Imbalances in ECF Volume

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Hypernatremia

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Manifestations include thirst, lethargy, agitation, seizures, and coma

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If secondary to water deficiency, it often results of impaired LOC

• •

Can be produced by clinical states such as central or nephrogenic diabetes insipidus Management includes

•

Treat underlying cause If oral fluids cannot be ingested, IV solution of 5% dextrose in water or hypotonic saline  Diuretics Serum sodium levels must be reduced gradually to avoid cerebral edema  

Nursing Management Nursing Diagnosis •

Risk for injury

Hyponatremia • •

Results from loss of sodium-containing fluids or from water excess Clinical manifestations include confusion, nausea, vomiting, seizures, and coma

Hyponatremia • •

If caused by water excess, fluid restriction is needed If severe symptoms (seizures) occur, small amount of intravenous hypertonic saline solution (3% NaCl) is given

Hyponatremia •

If associated with abnormal fluid loss, fluid replacement with sodium-containing solution is needed

Nursing Management Nursing Diagnosis •

Risk for injury

Extracellular Fluid Volume Imbalances

• • •

•

Hypovolemia can occur with loss of normal body fluids (diarrhea, fistula drainage, hemorrhage), decreased intake, or plasma-to-interstitial fluid shift Hypervolemia may result from excessive intake of fluids, abnormal retention of fluids (CHF), or interstitial-to-plasma fluid shift Extracellular Fluid Volume Imbalances Treatment for hypovolemia is balanced IV solutions, isotonic chloride, or blood

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•

Treatment for hypervolemia is use of diuretics, fluid restriction, and sodium restriction

Nursing Management Nursing Diagnoses

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Hypovolemia:     

Excess fluid volume Ineffective airway clearance Risk for impaired skin integrity Disturbed body image Potential complications: pulmonary edema, ascites

Nursing Management Nursing Diagnoses •

Hypovolemia  Deficient fluid volume  Decreased cardiac output  Potential complication: hypovolemic shock

Nursing Management Nursing Implementation • • • • •

I&O Monitor cardiovascular changes Assess respiratory status and monitor changes Daily weights Skin assessment

Nursing Management Nursing Implementation •

Neurologic function  LOC  PERLA  Voluntary movement of extremities  Muscle strength  Reflexes

[Potassium] • •

Potassium major ICF cation Potassium is necessary for  Transmission and conduction of nerve impulses  Maintenance of normal cardiac rhythms  Skeletal muscle contraction  Acid-base balance

Potassium •

Critical to action membrane potential  Sources  Fruits and vegetables (bananas and oranges)  Salt substitutes  Potassium medications (PO, IV)  Stored blood

Hyperkalemia

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•

Causes 

 

Increased retention  Renal failure  Potassium sparing diuretics Increased intake Mobilization from ICF  Tissue destruction  Acidosis

Hyperkalemia Clinical Manifestations • • • • •

Skeletal muscles weak or paralyzed Ventricular fibrillation or cardiac standstill Cardiac depolarization is impaired Repolarization occurs more quickly Abdominal cramping or diarrhea

Nursing Management Nursing Diagnoses • •

Risk for injury Potential complication: arrhythmias

Nursing Management Nursing Implementation • • • •

Eliminate oral and parenteral K intake Increase elimination of K (diuretics, dialysis, Kayexalate) Force K from ECF to ICF by IV insulin or sodium bicarbonate Reverse membrane effects of elevated ECF potassium by administering calcium gluconate IV

Hypokalemia •

Causes  Increased loss  Aldosterone  Loop diuretics  GI losses  Associated with Mg deficiency  Movement into cells

Hypokalemia Clinical Manifestations • • • • •

Potentially lethal ventricular arrhythmias Impaired repolarization Increased digoxin toxicity in those taking the drug Skeletal muscle weakness and paralysis Muscle cell breakdown  Leads to myoglobin in plasma and urine

Hypokalemia Clinical Manifestations • • • • •

Decreased GI motility Altered airway responsiveness Impaired regulation of arterial blood flow Diuresis Hyperglycemia

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Nursing Management Nursing Diagnoses • •

Risk for injury Potential complication: arrhythmias

Nursing Management Nursing Implementation •

•

Replacement PO or IV  Never push IV  Painful in peripheral veins  Never give with anuric renal failure Teach prevention methods

[Calcium] • • • •

Obtained from ingested foods More than 99% combined with phosphorus and concentrated in skeletal system Inverse relationship with phosphorus Bones readily available store of calcium

Calcium • • •

Calcium blocks sodium transport and stabilizes cell membrane Functions include transmission of nerve impulses, myocardial contractions, blood clotting, formation of teeth and bone, and muscle contractions Only ionized form of calcium is biologically active

Calcium

•

t

Controlled by   

Parathyroid hormone Calcitonin Vitamin D

Hypercalcemia • •

High serum calcium levels Causes include  Hyperparathyroidism  Malignancy  Vitamin D overdose  Prolonged immobilization

Hypercalcemia •

Clinical    

manifestations include decreased memory confusion disorientation fatigue

Hypercalcemia •

Management includes  loop diuretic  hydration with isotonic saline infusion

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 

synthetic calcitonin mobilization

Nursing Management Nursing Diagnosis • •

Risk for injury Potential complication: arrhythmias

Hypocalcemia • •

Low serum calcium levels Causes include  Decreased production of PTH  Acute pancreatitis  Multiple drug transfusions  Alkalosis  Decreased intake

Hypocalcemia •

Clinical manifestations include positive Trousseau’s sign and Chvostek’s sign

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Others include laryngeal stridor, dysphagia, numbness, and tingling around the mouth or in the extremities

Hypocalcemia •

Management  Treat cause  Oral or IV calcium supplements  Treatment of pain and anxiety to prevent hyperventilation-induced respiratory alkalosis

[Phosphate] • • •

Phosphorus is primary anion in ICF Essential to function of muscle, red blood cells, and nervous system Deposited with calcium for bone and tooth structure

Phosphate • • •

Involved in acid-base buffering system, ATP production, and cellular uptake of glucose Maintenance requires adequate renal functioning Essential to function muscle, RBCs, and nervous system

Hyperphosphatemia •

Causes   

 

include Acute or chronic renal failure Chemotherapy Excessive ingestion of milk or phosphate Containing laxatives Large intakes of vitamin D

Hyperphosphatemia Clinical Manifestations • •

Hypocalcemia Muscle problems (tetany)

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•

Deposition of calcium-phosphate precipitates in skin, soft tissue, cornea, viscera, and blood vessels

Hyperphosphatemia •

Management  Identifying and treating underlying cause  Restricting foods and fluids containing phosphorus  Adequate hydration and correction of hypocalcemic conditions  Sevelamer (Renagel)

Hypophosphatemia

•

Causes include    

Malnourishment/malabsorption Alcohol withdrawal Use of phosphate-binding antacids During parenteral nutrition with inadequate replacement

Hypophosphatemia Clinical Manifestations • • • • •

CNS depression Confusion Muscle weakness and pain Arrhythmias Cardiomyopathy

Hypophosphatemia •

Management  Oral supplementation  Ingestion of foods high in phosphorus  May require IV administration of sodium or potassium phosphate

[Magnesium] • • •

50-60% contained in bone A coenzyme in metabolism of protein and carbohydrates Factors that regulate calcium balance appear to influence magnesium balance

Magnesium • •

Acts directly on myoneural junction Important for normal cardiac function

Hypermagnesemia •

Causes include  Increased intake or ingestion of products containing magnesium when renal insufficiency or failure is present

Hypermagnesemia Clinical Manifestations • • • • • •

Lethargy Drowsiness N/V Reflexes impaired Somnolence Respiratory and cardiac arrest can occur

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Hypermagnesemia •

Management  Prevention  IV CaCl or calcium gluconate  Fluids

Hypomagnesemia •

Causes include  Prolonged fasting or starvation  Chronic alcoholism  Fluid loss

Hypomagnesemia   

Prolonged parenteral nutrition without supplementation Diuretics Osmotic diuretics from high glucose levels

Hypomagnesemia Clinical Manifestations • • • • •

Hyperactive deep tendon reflexes Tremors Seizures Cardiac arrhythmias Confusion

Hypomagnesemia •

Management  Oral supplements  Increase dietary intake  If severe, parenteral IV or IM magnesium

[Protein] Imbalances • •

Plasma proteins, particularly albumin, are significant determinants of plasma volume Hyperproteinemia is rare, but occurs with dehydration-induced hemoconcentration

Hypoproteinemia •

Caused by  Anorexia  Malnutrition  Starvation  Fad dieting  Poorly balanced vegetarian diets

Hypoproteinemia • • • •

Poor absorption can occur in certain GI malabsorptive diseases Protein can shift out of intravascular space with inflammation Hemorrhage Nephrotic syndrome

Hypoproteinemia Clinical Manifestations • •

Edema Slow healing

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• • • • •

Anorexia Fatigue Anemia Muscle loss Ascites

Hypoproteinemia Management   

High-carbohydrate, high-protein diet Dietary protein supplements Enteral nutrition or total parenteral nutrition

IV Fluids Purposes 

Maintenance



 When oral intake is not adequate Replacement 

When losses have occurred

IV Fluids • • •

IV fluids will cause electrolyte imbalances if not corrected Imbalances classified as deficits or excesses Sodium plays major role in homeostasis of ECF

D5W • • •

Isotonic Provides 170 kcal/L Free water  Moves into ICF  Increases renal solute excretion

D5W • • • •

Prevents ketosis Supports edema formation Decreased chance of IV fluid overload Usually compatible with medications

Normal Saline (NS) • • • •

Isotonic No calories More NaCl than ECF 30% stays in IV (most)  70% moves out of IV

Normal Saline (NS) •

• • •

Expands IV volume  Preferred fluid for immediate response  Risk for fluid overload higher Does not change ICF Volume Blood products Compatible with most medications

Lactated Ringer’s •

Isotonic

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•

More similar to plasma than NS

 

• •

l Has less Na Cl

l Has K, Ca, PO4, lactate (metabolized to HCO3) Expands ECF, IV Common replacement fluid

D5 ½ NS • • •

Hypertonic Common maintenance fluid KCl added for maintenance or replacement

D5 ½ NS •

Provides calories

 • •

Prevents ketosis

Moves into ICF Usually compatible with medications

D10W    

Hypertonic Provides 340 kcal/L Free water Limit of dextrose concentration may be infused peripherally

Plasma Expanders • •

Pull fluid into IV from interstitium Colloids  Packed RBCs  Albumin  Plasma

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