Fluid, Electrolyte and Acid-Base Balance The body normally maintains a balance between the amount of fluid

taken in and the amount excreted. Health promotion requires maintenance of body fluid and acid-base balance.

Body Water Distribution Water is the largest single

constituent of the body, representing 45% to 75% of the body’s total weight. About two-thirds of the body fluid is intracellular and remaining one-third is extracellular. Bones are made up of nearly one-third water, while the muscles and brain cells contain 70% water. Body fat is essentially free of water; therefore, the ratio of water to body weight is greater in leaner people than in obese people. Water is present in all body tissues and cells, and serves two main functions: to act as a solvent for the essential nutrients, so that they can be used by the body; and to transport nutrients and oxygen from the blood to the cells and to remove waste material and other substance from the cells back to the blood so they can be excreted by the body. Water is also needed by the body to:

• Give shape and form to the cells • Regulate body temperature • Act as a lubricant in joints • Cushion body organs

• Maintain peak physical performance

Water loss has a negative effect on the body’s ability to function, because every 2% to 5% of water loss results in a 30% decrease in work performance (Kloss, 1995; Kleiner, 1999).

Electrolytes An electrolyte is a compound that, when dissolved in water or

another solvent, forms or dissociates into ions (electrically charged particles). The electrolytes provide inorganic chemicals for cellular reactions and control mechanisms. Electrolytes have special physiological functions in the body, i.e. • Promote neuromuscular irritability, • Maintain body fluid osmolarity, • Regulate acid-base balance, and • Distribute body fluids between the fluid compartments.

Electrolytes are expressed as milliequivalents per liter (mEq/L). Because electrolytes produce either positively charged ions (cations) or

negatively charged ions (anions), they are critical regulators in the distribution of body fluid. The main electrolytes in body fluid are: • Sodium (Na+), • Potassium (K+), • Calcium (Ca2+), and • Magnesium (Mg2+)

Acid-Base Balance Acid-base balance refers to

the homeostasis of the hydrogen ion concentration in extracellular fluid. The slightest variation in the hydrogen ion concentration causes marked alterations in the rate of cellular chemical reactions. The pH symbol is used to indicate the hydrogen ion concentration of body fluids; 7.35 to 7.45 is the normal pH range of extracellular fluid.

When the number of free hydrogen ions increases to the point that the pH value becomes less than 7.35, the body is in a state of acidosis. The opposite occurs with alkalosis, in which a pH value higher than 7.45 results from a low hydrogen ion concentration.

The body has three main control systems that regulate acid-base balance to counter acidosis or alkalosis: • The buffer systems, • Respiration, and • Renal control of H+ concentration

Electrolyte Imbalances Sodium:

Causes: Hyponatremia :( Serum Sodium < 135 mEq/L)

• Loss of GI secretions (vomiting, diarrhoea, suctioning etc.) • Loss of ECF sodium (peritonitis, burns etc.) • ECF sodium dilution (CHF, cirrhosis, nephrosis) • Advanced renal disorders • Diuretics, ADH, or SIADH(syndrome of inappropriate ADH) Manifestations and Nursing Interventions:

Manifestations Nsg. Interventions Headaches, Apprehension, Lethargy, Confusion, Depression & convulsion

Admn. Comfort measures as needed Monitor level of consciousness Institute safety measures for seizure

Muscular Weakness Assist with range of motion Dry, pale skin & mucous Admn. IV isotonic solution (0.9%NaCl)

Tachycardia & Hypotension Monitor hourly vital signs & I/O Restrict fluids and Admn. diuretics

Nausea, vomiting, diarrhoea, abdominal cramps

Monitor daily intake of Na & watch for water intoxication with SIADH (Headache & behavioural changes)

Biochemical changes Monitor serum sodium levels Teach about intake of Na, side effects

of diuretics, & other causes.

Causes: Hypernatremia (Serum Sodium < 146 mEq/L)

• High sodium intake • Administration of IV fluids (hypertonic or isotonic saline) • Hypertonic saline abortions • Renal dysfunction • Uncompensated diabetes insipidus • CHF, Nephrotic syndrome and cirrhosis Manifestations and Nursing Interventions

Manifestations Nursing Interventions Restlessness, Agitation, Delirium, Convulsions, Coma

Monitor level of consciousness Institute Safety measures for seizures

Increased muscle tone, hyperreflexia

Maintain body alignment and assist with movement.

Flushed, dry skin, Red, dry tongue & sticky mucous Administer oral hygiene hourly.

Tachycardia Monitor vital signs hourly

Nausea, vomiting, anorexia Admn. oral fluid/parenteral hypotonic soln.(0.3%NaCl) as ordered

Polyuria Monitor I/O hourly

Biochemical Changes Monitor laboratory findings Teach about foods high in Na & about

Na-retaining drugs Potassium:

Causes: Hypokalemia (Serum Potassium < 3.5 mEq/L)

• Abnormal loss of K+ (K+ depleting diuretics e.g. thiazide, furosemide) • Inadequate replacement(malnutrition, starvation, NPO & K+ free IV fluids) • Increased movement into cells (possible when insulin given) • Adrenal tumor, Cirrhosis, CHF Manifestations and Nursing Interventions

Manifestations Nursing Interventions Abdominal Distention, nausea & vomiting

Admn. of K+ replacement therapy as ordered.

Malaise, disorientation, coma, loss of tactile discrimination

Admn. of Oral potassium should be diluted in 4-8 oz of water or juice

IV potassium 20-40mEq/ 1L of IV fluids Muscle weakness & hyporeflexia Protect from injury

Constipation & Polyuria Monitor I/O hourly Diminished breath sounds, tachycardia, Increased sensitivity to digitalis, ST depression, T-wave inverted, heart block, cardiac arrest(severe Hypokalemia)

Monitor vital signs hourly Monitor heart rate and rhythm Monitor closely for signs of digitalis

toxicity(premature atrial & ventricular beats)

Biochemical changes Teach client about K+ rich foods and

how to prevent excessive loss( abuse of laxatives and diuretics)

Electrolyte Normal values

Sodium 135-148 mEq/L

Potassium 3.5-5.0 mEq/L

Calcium 8.4-10.5 mg/dl

Magnesium 1.3-2.0 mEq/L

Phosphate 2.7-4.5 mg/dl

Chloride 96-109 mEq/L

Causes: Hyperkalemia (Serum Potassium > 5.0 mEq/L)

• Acute and chronic renal failure • Cellular damage (K+ released into ECF when cells destroyed) • Insulin deficiency • Adrenal deficiency • Rapid IV infusion of K+ Manifestations and Nursing Interventions

Manifestations Nursing Interventions

Abdominal cramps, nausea, diarrhoea

Restrict oral and parenteral potassium intake as ordered

Admn. of ion exchange resins(Kayexalate) Muscular weakness, paresthesias, muscle cramps & pain

Assess for pain and provide comfort measures as indicated

Oliguria or anuria Monitor I/O hourly Bradycardia, T-wave tented, QRS complex widened, Life-threatening dysrhythmias

Monitor vital signs & heart rhythm hourly for ECG changes

Biochemical changes Teach client about K+ rich foods, K+ conserving diuretics etc.

Calcium:

Causes: Hypocalcemia (Serum Calcium < 8.4 mg/dl)

• Parathyroid deficiency • Poor vitamin D intake and absorption • Some malignancies • Inadequate dietary intake (e.g. during pregnancy and lactation) Manifestations and Nursing Interventions

Manifestations Nursing Interventions Anxiety, irritability, tingling and numbness of fingers, tetany, convulsions

Monitor client’s state of sensorium for safety factors and breathing for laryngeal stridor

Laryngospasm, abdominal and muscle cramps, pathologic fractures

Admn. of 10% calcium gluconate Admn. of calcium lactate orally Diet high in Ca2+ with Vit.D supplement

Decreased stroke volume, ST segment lengthened, prolonged PR interval

Monitor ECG for changes

Causes: Hypercalcemia (Serum Calcium > 10.5 mg/dl)

Bone tumors, immobility Overconsumption of milk or dietary salts Hyperparathyroidism Renal impairment Manifestations & Nursing Interventions

Manifestations Nursing Interventions Depression & Lethargy Monitor State of sensorium

Decreased muscle tone & deep tendon reflexes, osteoporosis, osteomalacia, deep bone pain

Encourage client movement and exercise Assist client with movement to decrease

pain

Heart block, Arrest(Hypercalcemia crisis) Monitor for ECG changes

Nausea, vomiting, anorexia, constipation

Teach to decrease Ca2+ intake & increase fibre

Flank pain from calculi, Polyuria

Encourage oral intake of acid-ash fluids to decrease deposit of calcium salts.

Magnesium:

Causes: Hypomagnesemia (Serum Magnesium < 1.3 mEq/L)

• Impaired intake (impaired intestinal absorption) • Excessive urinary excretion (diuretics and alcoholism) • Severe renal disease Manifestations and Nursing Interventions

Manifestations Nursing Interventions Disorientation, Confusion, Vertigo, Tremors, Irritability

Monitor for seizure activity & laryngeal stridor

Increased tendon reflexes Increased BP, Tachycardia, T-wave flat or inverted, ST segment depressed

Monitor for ECG changes Assess the client for digitalis toxicity

Biochemical changes Teach to avoid excess use of laxatives

Causes: Hypermagnesemia (Serum Magnesium > 2mEq/L)

• Renal failure (diabetic ketoacidosis) • Excessive treatment of magnesium deficit Manifestation and Nursing Interventions

Manifestations Nursing Interventions Lethargy, Drowsiness, Coma Monitor level of consciousness Muscle weakness, decreased deep-tendon reflexes

Assess patellar reflexes, if absent notify practitioner

Decreased Resp. & BP, Bradycardia, QRS complex widening, QT interval prolonged

Monitor vital signs q15-30mins & for ECG changes

Encourage fluids unless contraindicated

• Sue C. DeLaune, Patricia K. Ladner; FUNDAMENTALS OF NURSING: STANDARDS & PRACTICE; 2nd Edition, Delmar, Thomson learning Inc.

References:

• Springhouse; FLUIDS AND ELECTROLYTES MADE INCREDIBLY EASY; 2nd Edition. Springhouse

• Urden L, Davie J, Thelan L; ESSENTIALS OF CRITICAL CARE NURSING; Mosby year book

Prepared By,

Mr. Prasanth Kurien Mathew, Ist Yr M.Sc (N), SCON, Salem (2009)