8.1 Fluid and Electrolytes Imbalances

Intracellular Fluid Compartment (ICF)

Fluid found inside the cells. It comprises 2/3 (67%) of the total body water.

Extracellular Fluid Compartment (ECF)

Fluid found outside the cells. It comprises 1/3 (33%) of the total body water. One-third (1/3) of the ECF is in plasma.

Total Body Water (TBW)

TBW = (Weight in kg) × (0.6 for males or 0.5 for females).

Intracellular Fluid Volume Calculation

ICF = (Total Body Water) × (0.63).

Extracellular Fluid Volume Calculation

ECF = (Total Body Water) × (0.37).

Plasma Volume Calculation

Plasma = (Extracellular Fluid Volume) / 3.

Serum Osmolality

Reflects the amount of solute particles in a solution and is a measure of the concentration of a given solution.

Serum Osmolality Calculation

Serum Osmolality = (2 × Na) + (Glucose/18) + (BUN/3).

Normal Serum Osmolality Value

Normal value = 275 - 290 mOsm/kg.

Sodium (Na+)

The primary extracellular cation, normal range is 135 - 145 meq/L.

Hyponatremia

Defined as serum sodium less than 135 meq/L. It is the most common electrolyte abnormality observed in a general hospitalized population.

Causes of Hyponatremia

Diuretics, low sodium diet, excessive ingestion of plain water, profuse diaphoresis & diuresis, administration of electrolyte-free solution, prolonged vomiting, GI suctioning, draining fistulas, edema, ascites, burns, Addison's disease.

Clinical Manifestations of Hyponatremia

Headache, muscle weakness, fatigue and apathy, anorexia, nausea and vomiting, abdominal cramps, weight loss, postural hypotension, seizure, coma.

Hyponatremia Treatment

Administration of NaCl 0.9% per IV, plasma expanders (hetastarch), sodium-rich foods in diet.

Hyponatremia Nursing Management

Identify and monitor patients at risk, monitor I&O, daily body weight, safety precautions.

Hypernatremia

Serum sodium greater than 145 meq/L, develops from excess water loss, frequently accompanied by an impaired thirst mechanism.

Causes of Hypernatremia

Sodium tablets, hypokalemia, hypercalcemia, or sickle cell anemia can cause nephrogenic diabetes insipidus.

Clinical manifestation of Hypernatremia

Extreme thirst, dry sticky mucous membranes, oliguria, firm rubbery tissue turgor, fever, rough red dry swollen tongue, lethargy, restlessness, tachycardia, fatigue, disorientation, hallucination, and coma if severe.

Clinical Findings of Hypernatremia

Intact thirst mechanisms usually prevent hypernatremia. Its presence is commonly associated with encephalopathy of any cause, or cerebrovascular disease. Orthostatic hypotension and oliguria are typical.

Treatment for Hypernatremia

Low sodium diet, increase oral fluid intake or administer D5W per IV, diuretics, dialysis, and directed toward correcting the cause of fluid loss and replacing water and, as needed, electrolytes.

Calculation of water deficit for Hypernatremia

Volume to be replaced = current TBW x ([Na] - 140) / 140, where [Na] is the measured serum sodium.

Example of water deficit calculation

For a 32y/o 60kg male patient with serum sodium of Na+160 meq/L, TBW = (60 kg) (0.6) = 36 kg → 36 liters.

Volume to be replaced example

= 36 x (160 - 140) / 140 = 36 x 20 / 140 = 36 x 0.14285 = 5.14 liters.

Nursing management for Hypernatremia

Monitor fluid losses and gains, obtain medication history, check for OTC medications, monitor intake and output, restrict sodium diet, administer diuretics as prescribed, and promote safety.

Potassium normal range

3.5 - 5.0 meq/L, major intracellular cation.

Functions of Potassium

Regulates protein synthesis, glucose use and storage, and maintains action potentials in excitable membranes.

Hypokalemia

A total body deficit of about 350 mEq occurs for each 1 meq/L decrement in serum potassium concentration.

Causes of Hypokalemia

K+ wasting diuretics, severe vomiting and diarrhea, draining intestinal fistula, prolonged suctioning, large doses of corticosteroids, IV administration of insulin and glucose, and prolonged administration of non-electrolyte parenteral fluids.

Clinical Manifestations of Hypokalemia

Due to decreased neuromuscular irritability, symptoms include anorexia, nausea, vomiting, abdominal distention, and paralytic ileus.

Fluid loss causes of Hypernatremia

Profuse watery diarrhea, excessive salt intake without sufficient water intake, decreased water intake, excessive administration of sodium solutions, and excessive water loss without accompanying sodium loss.

Sodium Imbalances

High impact concepts include Hyponatremia (increase ICF volume = cell swell) and Hypernatremia (decrease ICF volume = cell shrink).

Oliguria

A condition characterized by reduced urine output, often associated with hypernatremia.

Disorientation and hallucination

Neurological symptoms that may occur in severe cases of hypernatremia.

Coma

A severe state of unresponsiveness that can occur in extreme cases of hypernatremia.

Fever

A clinical sign that may accompany hypernatremia.

Dry, sticky mucous membranes

A physical finding often seen in patients with hypernatremia.

Firm, rubbery tissue turgor

A clinical sign indicating dehydration, often present in hypernatremia.

Rough, red, dry swollen tongue

A clinical manifestation that may be observed in hypernatremia.

Lethargy

A state of sluggishness or lack of energy.

Diminished deep tendon reflexes (hyporeflexia)

Reduced response of muscles to stimuli.

Confusion

A state of being bewildered or unclear in one's mind.

Mental depression

A mood disorder characterized by persistent feelings of sadness and loss of interest.

Weakness

A lack of physical strength or vigor.

Fatigue

A state of extreme tiredness resulting from mental or physical exertion.

Leg cramps

Involuntary contractions of the muscles in the leg.

Flaccid paralysis

A condition where muscles are weak and unable to contract.

Weakness of respiratory muscles

Reduced strength in the muscles that facilitate breathing.

Tetany

A condition characterized by muscle spasms and cramps.

Rhabdomyolysis

A serious syndrome caused by muscle injury leading to the release of muscle fiber contents into the bloodstream.

Hypotension

Abnormally low blood pressure.

Dysrhythmias

Abnormal heart rhythms.

Myocardial damage

Injury to the heart muscle.

Cardiac arrest

A sudden stop in effective blood circulation due to the failure of the heart to contract effectively.

Water loss

The process of losing fluid from the body.

Thirst

The sensation of needing to drink fluids.

Renal damage

Injury to the kidneys affecting their function.

ECG changes

Alterations in the electrocardiogram readings indicating heart function.

ST-segment depression

A finding on an ECG indicating potential heart issues.

Flat or inverted T wave

Changes in the T wave of an ECG that may indicate cardiac problems.

Increased U wave

An abnormal finding on an ECG that may suggest hypokalemia.

Potassium Chloride (KCl)

A potassium supplement that should not be administered via IV push due to the risk of dysrhythmias.

Hyperkalemia

Increased neuromuscular irritability; main route for potassium excretion are the kidneys.

Calcium (Ca2+) Normal Range

8.5 - 10.5 mg/dL; important for bone strength & density, activation of enzymes or reactions, skeletal/cardiac muscle contraction, nerve impulse transmission, and blood clotting.

Calcium in Plasma

In plasma, calcium is present as a non-diffusible complex with protein (33%); as a diffusible but undissociated complex with anions like citrate, bicarbonate, and phosphate (12%); and as ionized calcium (55%).

Ionized Calcium Normal Range

4.7 to 5.3 mg/dL; necessary for muscle contraction and nerve function.

Hypocalcemia Causes

Decrease dietary intake, excess loss of calcium (renal disease, draining fistula), decreased calcium absorption (vit D deficiency, hypoparathyroidism, hyperthyroidism, hypermagnesemia), acute pancreatitis, corticosteroids, rapid administration of multiple units of blood that contain an anticalcium additive, intestinal malabsorption, accidental removal of parathyroid glands.

Hypocalcemia Clinical Manifestation - CNS

Tingling, convulsions.

Hypocalcemia Clinical Manifestation - GI

Increased peristalsis, nausea and vomiting, diarrhea, abdominal pain.

Hypocalcemia Clinical Manifestation - Muscles

Muscle spasm, laryngospasm with stridor, tetany (Chvostek's sign and Trousseau's sign).

Hypocalcemia Clinical Manifestation - Cardiovascular

Dysrhythmias, cardiac arrest.

Hypocalcemia Clinical Manifestation - Bones

Osteoporosis, fracture due to decreased calcium deposited into the bones.

Hypocalcemia Laboratory Findings

Low serum calcium, elevated serum phosphorus, low serum magnesium, prolonged QT interval on the ECG.

Hypocalcemia Treatment - Asymptomatic

High calcium diet, oral calcium and vitamin D preparations; calcium carbonate is well tolerated and inexpensive.

Hypocalcemia Treatment - Severe Symptomatic

Calcium gluconate 10% administered intravenously for 10-15 minutes or via calcium infusion; 10-15 mg of calcium per kilogram body weight, or 6-8 10-ml vials of 10% calcium gluconate (558-744 mg of calcium) added to 1 liter of D5W and infused over 4 to 6 hours.

Hypocalcemia Nursing Management

Closely monitor for neurologic manifestations (tetany, seizures, spasms), seizure precautions, provide bed rest for comfort, avoid falls, monitor breathing (laryngospasm), check for signs of bruising or bleeding.

Hypocalcemia High Impact Concept

To remember clinical manifestations.

Hypercalcemia Causes

Excessive intake of calcium, excessive doses of vitamin D, calcium loss from bone (immobilization, carcinoma with bone metastases), parathyroid gland tumors, multiple fractures, hyperparathyroidism, certain malignant diseases (multiple myeloma, acute leukemia, lymphomas).

Hypercalcemia Clinical Manifestations - CNS

Diminished deep-tendon reflexes, lethargy, mental changes (decreased memory & attention span), coma.

Hypercalcemia Clinical Manifestations - GI

Decreased peristalsis (constipation, paralytic ileus).

Hypercalcemia

A condition characterized by elevated calcium levels in the blood.

Clinical manifestations of Hypercalcemia

Signs and symptoms including depressed electrical activity in the cardiovascular system, cardiac arrest, deep bone pain, osteoporosis, pathologic fractures, thirst, polyuria, dehydration, stones, and renal damage.

Treatment for Hypercalcemia

Includes determining and correcting the cause, increasing fluid intake (3-4L/day), limiting calcium consumption in mild cases, providing acid-ash fruit juice (Cranberry & prune juice) and vitamin C, administering 0.45% or 0.9% NaCl in acute cases, and using diuretics like furosemide.

Nursing Management for Hypercalcemia

Encourages increased fluid intake, a high fiber diet, collaboration with dietitians to limit food sources of calcium, ambulation as tolerated, providing assistance to avoid falls, monitoring cardiac rate and rhythm for abnormalities.

Magnesium (Mg2+) normal range

Normal plasma concentration is 1.5-2.5 meq/L, with about one-third bound to protein and two-thirds existing as free cation.

Hypomagnesemia

A condition where magnesium levels are low, often unrecognized in hospitalized patients, leading to complications like arrhythmias and sudden death.

Causes of Hypomagnesemia

Includes chronic alcoholism, severe renal disease, severe malnutrition or starvation, intestinal malabsorption syndromes, excessive diuresis, prolonged gastric suction, and draining fistula.

Clinical manifestations of Hypomagnesemia

Includes convulsions, paresthesia, tremors, ataxia, agitation, depression, confusion, muscle weakness, cramps, spasticity, tachycardia, hypertension, dysrhythmias, and positive Babinski response.

Laboratory Findings in Hypomagnesemia

Decreased serum magnesium levels, hypocalcemia, hypokalemia, prolonged QT interval, and lengthening of the ST segment on the ECG.

Treatment for Hypomagnesemia

Involves a magnesium-rich diet and intravenous fluids containing magnesium, with dosages of 240-1200 mg/day during severe deficit and 120 mg/day for maintenance.

Nursing Management for Hypomagnesemia

Encourages food rich in magnesium, promotes safety, monitors for laryngeal stridor, and administers magnesium supplements as prescribed.

Hypermagnesemia

A condition almost always resulting from renal insufficiency, leading to impaired central nervous system and muscular function.

Causes of Hypermagnesemia

Includes excessive intake of magnesium-containing antacids, renal failure, and diabetic ketoacidosis (DKA).

Clinical Manifestations of Hypermagnesemia

Includes symptoms related to impaired central nervous system and muscular function.

Muscle fatigue

A condition characterized by a decrease in the muscle's ability to generate force.

Hypotonia

A state of decreased muscle tone.

Nausea & vomiting

Symptoms often associated with gastrointestinal disturbances.

Deep bone pain

Intense pain originating from the bones, often associated with conditions like osteoporosis.

Osteoporosis

A condition characterized by weakened bones and an increased risk of fractures.

Pathologic fractures

Fractures that occur with minimal or no trauma due to underlying disease.

Polyuria

Excessive urination, often a symptom of underlying health issues.