| ID | 165 |
|---|---|
| Name | METABOLIC ALKALOSIS |
| Cause | Causes: 1. Excessive ingestion of absorbable alkali. 2. Loss of acid from the stomach by repeated vomiting |
| Signs Symptoms | |
| Diagnosis | |
| Investigations | |
| Management | |
| Introduction | Metabolic alkalosis is characterized by an increase in plasma bicarbonate, a fall in blood [H+], and a small compensatory rise in PaCO2. Metabolic alkalosis is generally associated with hypokalemia, this is partly due to the direct effect of alkalosis on renal potassium excretion and partly due to secondary hyperaldosteronism from volume depletion. The hypokalemia produced in this manner further worsens the metabolic alkalosis by increasing bicarbonate reabsorption in the proximal tubule and hydrogen ion secretion in the distal tubule. The administration of KC1 will correct the disorder. Metabolic alkalosis, on the basis of its causes, may be classified as below viz- A. Saline-responsive metabolic alkalosis (common type): This is characterized by normotensive extracellular volume contraction and hypokalemia. Less frequently, hypotension or orthostatic hypotension may be seen. B. Saline-unresponsive alkalosis: 1. Hyperaldosteronism- Primary hyperaldosteronism causes, expansion of extracellular volume with hypertension. Metabolic alkalosis with hypokalemia results from the renal mineralocorticoid effect. 2. Alkali administration with decreased GFR- Usually urinary excretion of bicarbonate is decreased in CKD. If large amounts of HCO3 or metabolizable salts of organic acids (such as sodium lactate, sodium citrate, or sodium gluconate) are consumed, as with antacid therapy, metabolic alkalosis will occur. |
| History | |
| Etiology | |
| Clinical Features | Clinical features: The most striking feature of severe alkalosis is Cheynestokes respiration with periods .of apnoea. Tetany sometimes occur. Latent tetany is more common and can be unveiled by Trousseau’s sign. Apathy, personality change, delirium and stupor may occur in severe case. Severe alkalosis may result in renal epithelial damage and consequent renal insufficiency. |
| Preventions | |
| Treatment | Treatment: 1. Treatment of metabolic acidosis: The cause of metabolic alkalosis should be removed first and where possible a high urinary output is encouraged. In patients with pyloric stenosis the volume of the ECF should be restored and hypochloremia corrected using isotonic NaCl solution, usually 2-4 litres/day. Equal volume of gastric solution (NaCl 63mmol/L, KC1 17mmol/L, NHC1 90mmol/L) is to be given to the patient who require continuous gastric aspiration. Treatment also includes restoration of normal body water volume. Patients with impaired kidney function, may require dialysis with low-bicarbonate dialysate. 2. Correction of hypokalemic: One ampoule of 20mEq (mmol) of potassium chloride is added to 500ml of 5% dextrose solution & given intravenously. |
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