Fluid and Electrolytes Flashcards

Fluid and Electrolytes Homeostasis

• Goal: Maintain fluid and electrolyte balance for every cell, tissue, and organ system.
• Solvent: Fluid (e.g., water).
• Solutes: Particles, including electrolytes/ions.
• Intracellular Fluid (ICF): Fluid inside the cell.
• Extracellular Fluid (ECF): Fluid outside the cell.
• Interstitial Fluid: Located throughout the body; imbalance leads to edema.
• Water:
  • Vital nutrient.
  • Primary fluid in the body.
  • Average adult: 60% water.
  • Higher in children, lower in elderly.
  • Muscle holds water, fat detracts water.
  • Women < Men.
  • Daily need: 2-3 L/day.
  • Sources: Food and beverages (except alcohol).
  • 1 \text{ L} = 1 \text{ kg}

Fluid Movement

• Filtration: Moves fluid by hydrostatic pressure (high to low). "Water-pushing" pressure. Clinical sign: Edema.
• Diffusion: Movement of solutes (particles) from high to low concentration until equilibrium is achieved. Example: Food coloring in water, smoke/gas exchange.
  • Affected by:
    • Concentration gradient: Based on size and amount of particles.
    • Temperature.
  • Facilitated diffusion: Requires assistance for some particles to move. Clinical Example: Glucose transport.
• Osmosis: Movement of water only down its concentration gradient. "Water-pulling" pressure.
  • Requires:
    • Membrane separating two fluid spaces.
    • One space contains non-diffusible solutes.
  • Osmolarities of a solution determine:
    • Isotonic: Stays equal (no net movement).
    • Hypertonic (hyperosmotic): High solute concentration; water is pulled in to dilute.
    • Hypotonic: Low solute concentration; water is pulled out (water pushing).

Fluid and Electrolyte Balance

• Affected by: Age, gender, and fat content.
• Average fluid intake: 2-3 L/day.
• Fluid Intake:
  • Thirst center regulation.
  • Intake from fluids and food.
  • Catabolism.
• Fluid Loss:
  • Kidneys (urine).
  • Skin (sweating - insensible water loss).
  • Lungs (respiration - insensible water loss).
  • GI tract (feces).
  • Drainage from wounds, GI suction, and salivation.

Regulation of Fluid Balance

• Aldosterone:
  • Produced in the adrenal cortex.
  • Reabsorbs sodium and water.
  • Prevents hyponatremia and hyperkalemia.
  • Action: "Hold onto sodium and water, and get rid of potassium."
• Antidiuretic Hormone (ADH):
  • Also known as vasopressin.
  • Prevents fluid loss.
  • Causes vasoconstriction.
• Natriuretic Peptides (NPs):
  • ANP: Atrial natriuretic peptide.
  • BNP: Brain natriuretic peptide.
• Renin-Angiotensin-Aldosterone System (RAAS):
  • Compensatory response.
  • Kidneys are key.
  • Renin \rightarrow Angiotensin (weak blood protein) \rightarrow Angiotensin I \rightarrow Combined with Angiotensin Converting Enzyme (ACE) \rightarrow Angiotensin II \rightarrow Vasoconstriction = Increased BP.
  • Activated during shock or severe stress.
  • UOP (urinary output) indicates adequate perfusion.
  • Hypertension patients: Avoid sodium.

Fluid Imbalances

Hypovolemia (Dehydration):

• Intake or retention less than needed.
• Results in fluid volume deficit.
• Common in very young, elderly, cognitively impaired, and immobile patients.
• Two Forms:
  • Actual: Fluid loss or inadequate intake.
  • Relative: Shifting of fluid (e.g., third spacing).
• Isotonic Dehydration:
  • Water and electrolyte loss are equal.
  • Most common type of fluid volume deficit.
  • Loss of isotonic fluid from ECF (plasma and interstitial spaces).

Assessment for Dehydration:

• History:
  • Height and weight: 1 L of water = 1 Kg change in body weight (best indicator).
  • Patient complaints: ring or shoes tightness, palpitations, lightheadedness.
  • Orthostatic Hypotension: Worsens with severe dehydration.
• Abnormal fluid losses:
  • Sweating, salivation, diarrhea, wound drainage, vomiting, polyuria.
• Therapies:
  • Surgery, excessive hypertonic enemas, diuretics, NG suction, NPO.

Systemic Assessment for Dehydration:

• Cardiovascular:
  • Increased heart rate.
  • Diminished/absent peripheral pulses, thready pulse.
  • Weight loss.
  • Decreased blood pressure.
  • Decreased central venous pressure.
  • Orthostatic hypotension, flat neck/hand veins in dependent positions.
• Respiratory:
  • Increased rate and depth, tachypnea.
  • Confusion.
  • Hypoxia (apply oxygen).
• Integumentary:
  • Dry, scaly skin, poor turgor; tenting present.
  • Dry oral mucous membranes, note pitting edema.
• Neurologic:
  • May be the first indicator of fluid balance issue.
  • Decreased central nervous system function, lethargic, comatose.
  • Mental status changes, fever (inadequate fluid for temperature regulation).
• Renal:
  • Volume and composition indicate hydration status.
  • Decreased UOP, increased specific gravity.
  • Monitor daily weights and I&O.
• Psychosocial:
  • Flat affect, delirium, anxious, coma, restless, confused.

Laboratory Assessment for Dehydration:

• No single lab test; combined labs with patient presentation/symptoms.
• Hemoconcentration.

Nursing Diagnosis:

• Restoring Fluid Balance:
  • Fluid replacement (oral or IV).
  • Diet.
  • Oral rehydration therapy.
  • Isotonic fluids.
• Medications: Correct underlying cause (Antidiarrheals, antiemetics (vomiting), antipyretic (fever)).
• Decreased Cardiac Output:
  • Assess heart rate, rhythm, and quality; assess BP.
  • Medications.
  • Decreased cardiac output = decreased urinary output.
• Impaired Oral Mucous Membrane:
  • Assessments.
  • Medications: IV fluid replacement, saliva substitutes.
  • Oral hygiene: Avoid commercial mouthwash.

Fluid Overload (Hypervolemia)

• Excessive fluid in ECF.
• Causes: Poor IV therapy control, decreased cardiac output (heart failure), renal failure, long-term corticosteroid therapy, blood transfusions.
• Can lead to circulatory overload, edema, heart failure, pulmonary edema.

Systemic Assessment for Overhydration:

• Cardiovascular:
  • Increased HR: bounding pulse, increased BP, distended neck vein, weight gain.
• Respiratory:
  • Increased rate, shallow respirations, SOB, moist crackles with auscultation (pulmonary edema).
• Skin and mucous membranes:
  • Pitting edema in dependent areas, pale, cool skin.
• Neuromuscular:
  • Altered LOC, skeletal muscle weakness, headache, paresthesia, visual disturbances, seizures.
• Renal:
  • Decreased specific gravity.
• GI:
  • Increased motility, enlarged liver, diarrhea, ascites.

Interventions for Overhydration:

• Patient safety: more frequent bathroom visits.
• Medications: Diuretics.
• Nutritional Therapy: Fluid restriction + sodium restriction.
• I&O: Accuracy and consistency.

Fluid retention is not always visible. Rapid weight gain is the best indicator of fluid retention

Discharge Teaching for Overhydration:

• Daily weights: Keep a journal.
• Notify healthcare provider: Gain of 3 lbs in a week or 2 lbs in 24 hours.

Electrolyte Balances and Imbalances

Small changes = major problems

Sodium (Na^+)

• Serum sodium level: 135-145 mEq/L
• Located outside the cell (Primarily ECF)
• Responsible for water balance, maintains BP, supports nerve and muscle function.
• Obtained primarily by food and fluid.
• Primarily regulated by kidneys by aldosterone, ADH, and NP.
• ECF determines whether water is retained, excreted, or moved.
• Responsible for:
  • Skeletal muscle contraction, muscle contraction

Hyponatremia

• Serum sodium <135 mEq/L
• Most common electrolyte imbalance
• Often occurs with fluid imbalance
• Slows cell depolarization, cellular swelling, impaired function
• Causes:
  • Increased sodium excretion (actual loss), NPO or low sodium diet
  • Freshwater drowning, dilutional hyponatremia (relative loss)
  • Excessive sweating, excessive ingestion of hypotonic fluids
  • Diuretics, wound drainage, inadequate sodium intake

Hyponatremia- Systemic Assessment

• Cerebral- behavior and LOC alterations
• Neurologically- motor strength and reflexes decrease
• GI- Bowel sounds increased
• Cardiovascular- heart rate
  • Hypovolemia: rapid, weak, thready
  • Hypervolemia: bounding, edema, moist respirations

Safety

• Seizure precautions
• Medication therapy
  • Hypovolemia: IV NS infusions (increase % of sodium IVF)
  • Hypervolemia: osmotic diuretics (mannitol- promotes excretion of water, not sodium)-Avoid other diuretics
• Diet
  • Increase oral intake
  • Restrical oral fluid intake
  • Monitor I&O

Hypernatremia

• Serum sodium level >145 mEq/L
• Initially causes irritability of excitable tissue
• Later causes cellular dehydration and decreased response
• Fluid imbalance often present
• Common cause
  • Actual increase- due to decreased sodium excretion
  • Renal failure, corticosteroids, cushing’s syndrome,too much IV sodium
  • Relative increase- due to decreased water intake

Hypernatremia- Systemic Assessment

• Central Nervous System
  • normal or hypovolemia- agitation, seizures
  • Hypervolemia: lethargy, coma
• Neuromuscular
  • mild rises: assess muscles (twitching)
  • Higher rises: assess hand grips (weakness)
• Cardiovascular
  • decreased heart rate
• Muskuloskeletal
  • Increased restlessness, twitching

Safety:

• Seizure precautions
• Medication therapy
  • Hypotonic IV infusion (0.22% or 0.45% NS)
  • Diuretics: promoting sodium loss (Lasix and Bumex)
• Diet Therapy
  • Adequate fluid intake, sodium restricted diets:
• High sodium foods: frozen meals, tomato sauce, Soups, Condiments, Canned foods, Prepared mixes.
• Low sodium foods: Fruits, vegetables, grains, meat/fish/poultry/beans, dairy/flavors.

Potassium (K^+)

• Serum potassium level 3.5-5.0 mEq/dL -blood range is low and very narrow. Smallest changes can be serious
• Major cation of ICF (located inside cells.)
• Function
  • maintains action potential in cardiac tissue
  • Regulates glucose use and storage and protein synthesis
• Most dangerous electrolyte in the body when out of range

Hypokalemia

• Serum level <3.5 mEq/L
• Severity depends on how rapidly potassium drops
• Decreased excitability of cells
• Causes
  • Lack of dietary potassium, vomiting
  • NG tube suctioning, potassium wasting diuretics (Loop diuretics)
  • Shift of potassium from ECF to ICF.

Hypokalemia-Systemic Assessment

• History
  • age, chronic disorders, recent illnesses or surgeries, daily nutritional intake
• Medications
  • Diuretics. Loop diuretics deplete K. Aldactone/Spironolactone do not deplete K+. Loop diuretics do.
  • Corticosteroids
  • Digoxin (Lanoxin)-hypokalemia increases sensitivity of cardiac muscle \rightarrow Digoxin (Lanoxin) Toxicity
  • Potassium supplements
• Respiratory
  • Shallow respirations due to muscle weakness
  • Ease, breath sounds, color of nail beds, mucous membranes, rate, depth
• Musculoskeletal
  • Skeletal muscle weakness- difficulty standing, weakened hand grips, decreased DTR (hyporeflexia)
• Cardiovascular
  • slow heart rate to rapid and irregular
  • dysrhythmias, peripherial pulse, orthostatic BP
• Neurologic
  • Anxiety, Confusion, AMS/behavioral changes, Coma
• GI
  • decreased peristalsis
• Laboratory Diagnostic Tests
  • Potassium <3.5 mEq/L, EKG Changes

Hypokalemia- Nursing Interventions

• Prevent further loss
• Priority
  • adequate oxygenation
  • Patient safety, Prevent injury from potassium infusion
• Respiratory muscle weakness
  • Hypoventilation, respiratory weakness
• Cardiac Muscle Weakness
  • arrhythmias, weak irregular pulse, hypotension
• Skeletal muscle weakness
  • falls
• Smooth muscle atony
  • decreased bowel sounds. Constipation, paralytic ileus
• Medications
  • Potassium replacement IV: is only given with extreme caution. MUST BE DILUTED-Severe tissue irritant \rightarrow Necrosis-Prepared by licensed pharmacist
  • Potassium PO Liquid or pill form-Unpleasant/Bitter-Can cause N/V
  • Potassium sparing diuretics- Aldactone (Spironolactone)-Avoid potassium wasting diuretics
• Nutrition
  • Increase potassium intake-Meats, Dairy Products, Fruits high in Potassium (banana, cantaloupe, kiwi, oranges) Vegetables high in K+: avocados, broccoli, dried beans/peas
• Safety
  • Fall precautions.

Hyperkalemia

• Serum potassium >5.0 mEq/L
• Alters functions of ALL excitable membranes to some degree
• Heart extremely sensitive to potassium increases-Most serious effect is altered cardiac function
• Common causes
  • Over ingestion of potassium rich foods, rapid transfusion of potassium containing IVF
  • Transfusion of whole blood or packed red blood cells, potassium retaining diuretics
  • Renal dysfunction

Hyperkalemia- Systemic Assessment

• Cardiovascular
  • ECG changes, asystole
• Neuromuscular
  • Early: twitching paresthesia-Late: weakness, paralysis of respiratory muscles
• GI
  • Early: hyperactive bowel sounds-Late: colon spasms, watery diarrhea.

Hyperkalemia- Nursing Interventions

• Eliminate extra K+
• Increase potassium excretion
• Move potassium from ECF to ICF with prescribed medications (Insulin & glucose)
• Cardiac monitoring
• Medications
  • Avoid potassium sparing
  • Kayexalate (sodium polystyrene sulfonate)- pulls potassium into the intestines-slow acting
  • Insulin administration
• Teach prevention
  • Diet- avoid salt substitutes
  • Medications- avoid potassium sparing diuretics
  • Home monitoring of pulse

Calcium

• Serum Calcium level 9-10.5
• Functions:
  • Maintenance of bone strength and density
  • Necessary for cardiac and muscle contraction; Nerve impulse transmission; Blood Clotting
• Absorption requires Vitamin D
• Stored in bones; Regulated by parathyroid gland

Phosphorus & Magnesium

• Phosphorus: Reciprocal relationship to magnesium

Diuretics

• Loop (Lasix, Bumex)
  • IV: 10-15 mins
  • PO: 45 mins-1 hr
  • S/E: Hypokalemia, hyponatremia, Hypotension, dehydration, decreased heart rate
• Thiazide: HCTZ
  • PO: Primarily gets rid of sodium (gets rid of water also)
• K+ sparing: Spironolactone/ Aldactone
  • Spares N+, water, and K+. Check heart rate and BP before and after. Also check K+.