Metabolic Alkalosis is an acid-base imbalance characterized by excessive loss of acid or excessive gain of bicarbonate produced by an underlying pathologic disorder. Metabolic alkalosis causes metabolic, respiratory, and renal responses, producing characteristic symptoms. This condition is always secondary to an underlying cause.
Metabolic alkalosis results from the loss of acid, retention of base with decreased serum levels of potassium and chloride. Other causes may include:
- Nasogastric tube drainage or lavage without adequate electrolyte replacement
- Use of diuretics
- Excessive intake of alkali (i.e., milk, baking soda, antacid)
Signs and Symptoms
Manifestations of metabolic alkalosis result from the body’s attempt to correct the acid-base imbalance, primarily through hypoventilation. Other manifestations may include:
- Picking at bedclothes (carphology)
- Cardiovascular abnormalities (i.e., atrial tachycardia).
- Uncorrected metabolic alkalosis may progress to seizures and coma.
- CONFIRMING DIAGNOSIS: Blood pH level greater than 7.45 and bicarbonate levels above 29 mEq/L confirms Metabolic Alkalosis.
- Urinalysis shows urine pH is usually about 7.0.
- Electrocardiogram may show low T wave, merging with a U wave and atrial or sinus tachycardia.
This condition does not occur in isolation but rather is a complication of a broader problem that may require inpatient care in a medical-surgical or subacute unit.
- Plans of care specific to predisposing factors
- Fluid and electrolyte imbalances
- Renal dialysis
- Respiratory acidosis (primary carbonic acid excess)
- Respiratory alkalosis (primary carbonic acid deficit)
- May exhibit: Tachycardia, irregularities/dysrhythmias
- May report: Diarrhea (with high chloride content)
- Use of potassium-losing diuretics (Diuril, Hygroton, Lasix, Edecrin)
- Laxative abuse
- May report: Anorexia, nausea/prolonged vomiting
- High salt intake; excessive ingestion of licorice
- Recurrent indigestion/heartburn with frequent use of antacids/baking soda
- May report: Tingling of fingers and toes; circumoral paresthesia
- Muscle twitching, weakness
- May exhibit: Hypertonicity of muscles, tetany, tremors, convulsions, loss of reflexes
- Confusion, irritability, restlessness, belligerence, apathy, coma
- Picking at bedclothes
- May report: Recent blood transfusions (citrated blood)
- May exhibit: Hypoventilation (increases Pco2 and conserves carbonic acid), periods of apnea
- History of Cushing’s syndrome; corticosteroid therapy
- Arterial pH: Increased, higher than 7.45.
- Bicarbonate (HCO3): Increased, higher than 26 mEq/L (primary).
- Paco2: Slightly increased, higher than 45 mm Hg (compensatory).
- Base excess: Increased.
- Serum chloride: Decreased, less than 98 mEq/L, disproportionately to serum sodium decreases (if alkalosis is hypochloremia).
- Serum potassium: Decreased.
- Serum calcium: Usually decreased. Prolonged hypercalcemia (nonparathyroid) may be a predisposing factor.
- Urine pH: Increased, higher than 7.0.
- Urine chloride: Less than 10 mEq/L suggests chloride-responsive alkalosis, whereas levels higher than 20 mEq/L suggest chloride resistance.
- ECG: May show hypokalemic changes including peaked P waves, flat T waves, depressed ST segment, low T wave merging to P wave, and elevated U waves.
- Achieve homeostasis.
- Prevent/minimize complications.
- Provide information about condition/prognosis and treatment needs as appropriate.
- Physiological balance restored.
- Free of complications.
- Condition, prognosis, and treatment needs understood.
- Plan in place to meet needs after discharge.
The following are the possible nursing diagnosis for Respiratory Acidosis:
- Ineffective Tissue Perfusion
- Acute Confusion
- Risk for Injury
Nursing Care Plan
Main Article: Metabolic Alkalosis Nursing Care Plan
Nursing Interventions & Considerations
- Dilute potassium when giving via I.V. containing potassium salts. Monitor the infusion rate to prevent damage and watch out for signs of phlebitis.
- Watch for signs of muscle weakness, tetany or decreased activity. Monitor vital signs frequently and record intake and output to evaluate respiratory, fluid and electrolyte status.
- Observe seizure precautions.