Metabolic alkalosis results from net acid loss or alkali gain in the extracellular fluid. Acid loss can result from vomiting, prolonged gastric suctioning, and diuretic use. Treatment is directed toward mineralocorticoid antagonism. Lethargy and stupor may occur from adverse effects on the cerebral circulation. Arrhythmias, especially due to digitalis toxicity, are common.
Therapy depends on whether the metabolic alkalosis is sensitive or resistant to chloride.
The chloride-sensitive forms respond to administration of chloride, such as in normal saline. Gastric acid and chloride losses can be reduced by giving a histamine-2 blocker or a proton pump inhibitor. Chloride-resistant forms require treatment of the underlying disorder or mineralocorticoid antagonism with spironolactone. Respiratory acidosis is caused by carbon dioxide retention from alveolar hypoventilation, which may result from disorders that depress the central respiratory center, restrict chest wall mobility, reduce pulmonary alveolar surface area, or narrow the upper airway. The elderly are at risk because of their reduced vital capacity and ventilatory responses to hypoxia and hypercapnia.