A 52-year-old man with gastric outlet obstruction secondary to a duodenal ulcer presents with hypochloremic, hypokalemic metabolic alkalosis. Which of the following is the most appropriate therapy for this patient?

Infusion of 0.9% normal saline (sodium chloride) will correct his hypovolemia and his metabolic alkalosis. The development of a clinically significant metabolic alkalosis is secondary not only to the loss of acid or addition of alkali but also to renal responses that maintain the alkalosis (paradoxical aciduria). The normal kidney can tremendously augment its excretion of acid or alkali in response to changes in ingested load. However, in the presence of significant volume depletion and consequent excessive salt and water retention, the tubular maximum for bicarbonate reabsorption is increased. Correction of volume depletion alone is usually sufficient to correct the alkalosis, since the kidney will then excrete the excess bicarbonate. HCl infusion is usually unnecessary. Acetazolamide can be utilized to increase renal excretion of bicarbonate but should be avoided in volume-depleted individuals. Moreover, to the extent that acetazolamide causes natriuresis, it will exacerbate the volume depletion.