3.2 Electrolyte Balance Flashcards
Physiological Factors Affecting Electrolyte Balance
- Kidneys excrete 1 electrolyte in replacement of another for example na/k or ca/p
- Electric neutrality is a must between body compartments. Even a small difference in mEq difference is enough to be a voltage difference.
Sodium/Chloride Balance
*Sodium (na+) 135-145 mEq/L
Sodium (Think Brain)
- Na+ consists of 90% of ECF Cations
- Regulates osmotic forces and water balance.
- Balance is maintained by kidneys and hormonal mediators.
- Sodium also regulates osmolarity, neuromuscular function for conduction of impulses, regulation of acid base balance in conjunction with HCO3, and membrane transport
Sodium/Chloride Balance
Chloride (Cl-) 95 - 105 mEq/L
- Major anion in the ECF.
- Provides electroneutrality
- Undergoes passive transport and follows active transport of sodium.
- Concentration of chloride varies inversely with concentration of bicarbonate (HCO3-)
Hyponatremia (Low Sodium)
3 Categories
- Sodium Loss, Water Gain, Insufficient Sodium Intake
Etiologies
Vomiting, Diarrhea, Fistulas, Nasogastric Suctioning (NG), Wound Drainage, Excessive Sweating, Burns, Salt Losing, Diuretics, SIADH, Adrenal Insufficiency.
Pathophysiology
- Hypoosmolar fluid shifts from ECF to ICF resulting in cellular swelling and potential for abnormal cell depolarization/repolarization.
Hyponatremia (cont)
Clinical Manifestations
Depressed Reflexes, Muscle Cramps, Lethargy, Confusion, Seizure, Coma
Potential Complications
Severe neurological changes. Assess neuro signs and GI Symptoms, maintain seizure precaution and strict fluid restrictions.
Management
- If caused by water excess then fluid restriction
- If caused by abnormal fluid loss then fluid replacement containing sodium. (0.9% Sodium Chloride Solution)
- Severe deficit and symptoms like seizures give small amounts of IV hypertonic saline solution (3% NaCl)
Hypernatremia (Excess Salt)
Etiology (causes)
- Acute Gain (Inappropriate administration of hypertonic saline solution or over secretion of aldosterone)
- Net Loss of water (fever, respiratory infection, profuse sweating, diarrhea, polyuria, diabetes)
Pathophysiology
- Hypertonicity of ECF and results in cellular dehydration
Clinical Manifestation
Thirst, Dry Mucous Membranes, Muscle Twitching, Hyperreflexia, Pulmonary Edema, Headaches and Seizures.
Hypernatremia (cont)
Potential Complications
- Seizure, Coma leading to irreversible brain damage
Nursing Management
- Maintain fluid balance. Return sodium to normal and prevent injury. Replace fluid deficit, monitor intake and output (I&O), daily weights, vital signs, assess skin turgor.
Adjustments to sodium should be slow and steady.
Decrease patient risk of injury by monitoring neuro signs, repositioning, and other safety measures.
Potassium (K+)
Potassium
3.5 - 5 mEq/L (ECF)
140 - 150 mEq/L (ICF)
(Think Heart)
- Major Intracellular Cation
- Major determinant of resting membrane potential for nerve impulse, cardiac rhythm, and muscle contraction
- Potassium is exchanged for (H+) in blood in acid base buffering system.
- Acidosis - Too much H+ in ECF so Potassium leaves cells and H+ goes into cells. This causes Hyperkalemia.
- Alkalosis - Potassium goes into cells and hydrogen leaves cells. This causes Hypokalemia.
Potassium (cont)
- Intracellular concentration is maintained by sodium-potassium pump in cells. Potassium moves out of cells when channels are open. Extracellular concentration is regulated by kidneys. Potassium is filtered in glomerulus and ~90% is reabsorbed in proximal tubule.
Hormonal Influence of Potassium
Aldosterone - Stimulated by increase in K+. Increased levels are then excreted by kidneys and sweat glands.
Catecholamines (epinephrine) - Influences movement of K+ into cells.
Insulin - Influences movement of K+ into cells.
Hypokalemia (Low Potassium)
Common Causes
- Deficit in potassium stores or abnormal movement of potassium into cells.
- Excess loss from kidneys/GI Tract
- Renal disorders, vomiting, diarrhea, intestinal drainage tubes, laxative abuse, diuretics.
Clinical Manifestations
- Cardiac Dysrhythmia, weak irregular pulse, weakness, confusion, muscle cramp, paralysis.
Potential complications
- Dysrhythmias
Hypokalemia (cont)
Management
- Oral or IV Potassium supplements.
- IV MUST BE DILUTED (do not exceed 10-20 mEq/hour)
to prevent hyperkalemia and cardiac arrest.
Hyperkalemia (Excess Potassium)
- Clinically significant at 6.0 mEq/L
- Life threatening at 8.0 mEq/L
80% of potassium leaves body from kidneys.
Etiology
- Decreased renal elimination, increased intake, burns, extensive surgery, trauma, crushing injuries, insulin deficits, decreased secretion of aldosterone,
Clinical Manifestations
- Dysrhythmia, cardiac arrest, muscle weakness, paresthesia, flaccid paralysis.
Hyperkalemia (cont)
Potential Complications
Dysrhythmia
Management
- Eliminate oral and parental Potassium intake.
- Increase elimination of K+ with diuretics, dialysis, kayexalate (K+ binding agent), force potassium into ICF with Sodium Bicarbonate (Base). Administer Calcium Gluconate IV to protect heart from elevated potassium.
Calcium (Ca+)
- 5 - 10.5 mg/dL
- Second Major ECF Cation
- More than 99% is combined with phosphorous and concentrated in skeletal system.
- 50% of calcium in the blood is bound to proteins (albumin)
- Calcium increased in Alkalemia and decreased in acidemia. (Inverse relationship with hydrogen)
