Fluid Balance, Electrolytes, and Acid-Base Disorders Chapter 31

Drugs Crystalloids and Colloids Electrolytes Acid- Base Agents Dextran 40 (Gentran 40, LMD, others) Electrolytes Sodium chloride (NaCl) Potassium chloride (KCL) Acid- Base Agents Sodium bicarbonate

Frequent indications for IV therapy Drugs to reverse: Fluid Balance Deficit/Excess Electrolyte Imbalance Acid-base Disorders

Body Fluid Compartments Intracellular Extracellular Interstitial Intravascular Transcelluar Diffusion Active Transport Osmosis

Frequent indications for IV therapy Fluid Volume Deficit ? Fluid Volume Excess ? Two basic types of replacement: Crystalloids Colloids

Crystalloids Contain electrolytes Used to replace fluids and promote urine output Capable of leaving plasma and moving to interstitial spaces and intracellular fluid Isotonic Hypertonic Hypotonic

Colloids Molecules too large to easily cross capillary membrane Stay in intravascular space Rapidly expand plasma volume Draw water from intracellular fluid and interstitial spaces into plasma

Electrolytes Positively or negatively charged inorganic molecules Essential to Nerve conduction, membrane permeability Water balance, other critical body functions

Electrolytes Sodium (135mEq/L-145mEq/L) Potassium (3.5mEq/L-5mEq/L Essential for maintaining osmolality, water balance, acid-base balance Potassium (3.5mEq/L-5mEq/L Essential for Proper nerve and muscle function Maintaining acid-base balance Imbalances can be serious , even fatal

Electrolytes Prototype drug: sodium chloride Mechanism of action: as electrolyte/sodium supplement Primary use: to treat hyponatremia when serum levels fall below 130mEq/L Adverse effects: hypernatremia and pulmonary edema

Sodium Replacement Therapy Assess sodium and electrolyte balance Be alert for signs of hyponatremia or hypernatremia Client should report symptoms that may relate to fluid overload Client should drink water or balanced sports drinks to replenish lost fluids and electrolytes

Electrolytes Prototype drug: potassium chloride Mechanism of action: as electrolyte/potassium supplement Primary use: to treat hypokalemia Adverse effects: GI irritation, hyperkalemia; contraindicated in clients with chronic renal failure or those taking potassium-sparing diuretic

Potassium Replacement Therapy Monitor for cardiac abnormalities Do not use with potassium-sparing diuretics Take with meals to avoid irritating GI tract Can be given PO/IV If IV, administer slowly No IV Push

Dextran 40 Colloid= plasma volume expander Mechanism of action: to maintain plasma osmotic pressure and transport substances through blood Primary use: restoration of plasma volume and blood proteins Adverse effects: overload

Alkalosis and Acidosis Normal narrow range 7.35-7.45 Acidosis is excess acid (pH below 7.35) Alkalosis is excess base (pH above 7.45) Both symptoms of underlying disorder Buffers (lungs/kidneys): Bicarbonate ions Phosphate ions

Alkalosis and Acidosis Respiratory Metabolic (Renal)

Pharmacotherapy of Acidosis Symptoms affect central nervous system Lethargy, confusion, coma Deep, rapid respirations in attempt to blow off excess acid Goal is to quickly reverse effects of excess acid in blood Administration of bicarbonate is appropriate pharmacotherapy

Acid-Base Agents Prototype: sodium bicarbonate Mechanism of action: to decrease pH of body fluids Primary use: acidosis or bicarbonate deficiency metabolic alkalosis caused by receiving too much bicarbonate ion and hypokalemia

Pharmacotherapy of Alkalosis Symptoms are due to central- nervous- system stimulation Nervousness, hyperactive reflexes, convulsions Slow, shallow respirations in attempt to retain acid Treatment Administration of ammonium chloride (severe cases) Administration of sodium chloride with potassium chloride (mild cases)