Fluid & Electrolyte Imbalance Overview

Fluid & Electrolyte Imbalance

• Body water accounts for 60% of body weight.
• Intracellular water comprises 40% of body weight.
• Extracellular water makes up 20% of body weight, further divided into interstitial fluid (28 liters), plasma (3.5 liters), and transcellular fluid (1 liter).
• Common body water intake sources include oral intake (1000 mL), food (1300 mL), and water of oxidation (200 mL).
• Daily water output includes urine (1500 mL), stool (200 mL), lungs (300 mL), and skin (500 mL).

Fluid Volume Deficit (Hypovolemia)

• Common causes: Hemorrhage, vomiting, diarrhea, burns, diuretic therapy, fever, impaired thirst.
• Signs/Symptoms: Weight loss, thirst, orthostatic changes in pulse rate and blood pressure, weak and rapid pulse, decreased urine output, dry mucous membranes, and poor skin turgor.

Fluid Volume Deficit - Assessment and Interventions

• Assessment: Measure all fluids entering and leaving the body, check electrolytes, CBC, urine-specific gravity (e.g., I&Os), assess for hypotension, weak pulses, and respiratory and tissue perfusion.
• Interventions: Diet therapy (mild to moderate dehydration), oral fluid replacement, oral rehydration therapy (solutions with glucose and electrolytes), IV therapy (fluid type depends on dehydration and cardiovascular status), daily weight monitoring, and observation for complications.
• Labs show: Increased hemoglobin (Hgb) and hematocrit (Hct), increased urine specific gravity, increased blood urea nitrogen (BUN), and creatinine.

Fluid Volume Excess

• Common causes: Congestive heart failure, early renal failure, IV therapy, excessive sodium ingestion, syndrome of inappropriate antidiuretic hormone (SIADH), and corticosteroids.
• Signs/Symptoms: Increased blood pressure, edema, weight gain, bounding pulse, venous distention, pulmonary edema, dyspnea, orthopnea, and crackles.
• Labs show: Decreased hemoglobin (Hgb) and hematocrit (Hct), decreased urine specific gravity.

Urine Specific Gravity

• Normal range is 1.002 to 1.030.
• High specific gravity (over 1.030) indicates dehydration (fluid volume deficit).
• Low specific gravity (below 1.002) suggests kidney's inability to concentrate urine (fluid volume excess).

Electrolyte Imbalance - Potassium

• Potassium regulates muscle contraction, especially in the heart.
• Normal potassium levels are 3.5-5.2 mEq/L in adults.

Hypokalemia (<3.5 mEq/L)

• Pathophysiology: Low potassium decreases cell excitability, making cells less responsive to normal stimuli.
• Contributing factors: Diuretics, shift into cells, digoxin, water intoxication, corticosteroids, diarrhea, and vomiting.
• Assessment Findings: Weakness, shallow respirations, muscle cramps, arrhythmias, lethargy, and a weak or thready pulse.
• Interventions: Encourage potassium-rich foods, K+ replacement (IV/PO), monitor lab values, discontinue potassium-wasting diuretics, and treat the underlying cause. Potassium is never administered via IV push or intramuscularly; it must be administered slowly in IV fluids.

Hyperkalemia (>5.2 mEq/L)

• Pathophysiology: High potassium increases cell excitability.
• Contributing factors: Increased K+ intake, renal failure, K+ sparing diuretics, shift of K+ out of cells, and various underlying conditions.
• Assessment Findings: Muscle cramps/weakness/paralysis, drowsiness, EKG changes (e.g., wide QRS, peaked T waves), arrhythmias, abdominal cramping, diarrhea, and oliguria (decreased urine output).
• Interventions: Eliminate K+ administration, increase K+ excretion (e.g., diuretics like Lasix, Kayexalate), and address underlying causes.

Sodium (Na) Levels

• Normal levels: 135-145 mEq/L

Hyponatremia (<135 mEq/L)

• Contributing factors: Excessive diaphoresis, wound drainage, NPO (nothing by mouth), congestive heart failure (CHF), low-salt diet, renal disease, and diuretics.
• Assessment findings: Generalized skeletal muscle weakness, headache, personality changes, shallow respirations, increased gastrointestinal motility, nausea, diarrhea, and increased urine output.
• Interventions/Treatment: Restore Na levels to normal, reduce sodium intake, restrict fluid intake. This correction should be gradual (caution against rapid correction).

Hypernatremia (>145 mEq/L)

• Contributing factors: Hyperaldosteronism, renal failure, corticosteroids, increased oral Na intake, Na-containing IV fluids, decreased urine output with increased urine concentration, diarrhea, dehydration, and fever or hyperventilation.
• Assessment findings: Spontaneous muscle twitching, irregular contractions, skeletal muscle weakness, diminished deep tendon reflexes, pulmonary edema (resp.), heart rate and blood pressure depending on vascular volume, decreased urine output, dry/flaky skin, and edema related to fluid volume changes.
• Interventions: Eliminate sodium administration, encourage and replace fluid carefully, administer diuretics as needed, and ensure adequate water intake.

Hypocalcemia (<9.0 mg/dL)

• Contributing factors: Decreased oral intake (e.g., lactose intolerance), decreased vitamin D intake, end-stage renal disease, diarrhea, acute pancreatitis, hyperphosphatemia, and immobility.
• Assessment findings: Irritable muscle twitches, positive Chvostek's and Trousseau's signs, respiratory failure due to muscle tetany, decreased pulse rate and blood pressure, diminished peripheral pulses, increased gastrointestinal motility, and diarrhea.
• Interventions: Calcium supplements, vitamin D, high calcium diet, seizure precautions.

Hypercalcemia (>10.5 mg/dL)

• Contributing factors: Excessive calcium intake, excessive vitamin D intake, renal failure, hyperparathyroidism, malignancy, and hyperthyroidism.
• Assessment findings: Neurologic changes (disorientation, lethargy, profound muscle weakness), ineffective respirations, increased heart rate and blood pressure, bounding peripheral pulses, positive Homan's sign, decreased motility and decreased bowel sounds, constipation and possible formation of renal calculi (in the kidneys)

Hypomagnesemia (<1.4 mEq/L)

• Contributing factors: Malnutrition, starvation, diuretics, aminoglycoside antibiotics, hyperglycemia, and insulin administration.
• Assessment findings: Positive Trousseau's sign, positive Chvostek's sign, hyperreflexia, seizures, ECG changes and dysrhythmias, shallow respirations, decreased gastrointestinal motility, anorexia, and nausea.
• Interventions: Eliminate contributing drugs, administer IV magnesium sulfate, assess deep tendon reflexes hourly, and adjust diet therapy as needed.

Hypermagnesemia (>2.0 mEq/L)

• Contributing factors: Increased magnesium intake and decreased renal excretion.
• Assessment findings: Reduced or weak deep tendon reflexes (DTRs), weak voluntary muscle contractions, drowsiness, bradycardia, peripheral vasodilation, hypotension, and ECG changes.
• Interventions: Eliminate contributing drugs, administer diuretics to promote magnesium excretion, and adjust diet to reduce magnesium intake and consider calcium gluconate to reverse cardiac effects.