Preparation for Chronic Hyperventilation

Alan Kaye was a member of a team providing plastic surgery at high altitude. For 2 days preceding the trip, he was advised to take a carbonic anhydrase inhibitor, acetazolamide, which would effectively slow the normal reversible reaction between carbonic acid and its dissociation products, carbonic acid and water. The drug alkalinizes the urine and produces a moderate metabolic acidosis, the typical response to hypoxic hyperventilation at altitude. A typical blood gas determination after acclimatization to altitude is pHa = 7.42, PaCO₂ = 31 mm Hg, BE = 4 mEq/L, bicarbonate = 19, and PaO₂ = 80 mm Hg.

The benefit of taking acetazolamide is debated by climbers, and the drug is not without side effects. During the initial experience of taking acetazolamide at sea level, a striking, if minor, side effect is the metallic taste associated with drinking any carbonated beverage, presumably attributable to the inability to convert the high carbon dioxide content in the beverages to carbonic acid.