Hypoxemia From Sublingual Nitroglycerin

Kopman et al¹ accidentally discovered that after the administration of nitroglycerin in the course of induction of anesthesia for cardiac surgery, some patients had surprisingly low Pao₂ values. Therefore, these investigators undertook a special study of the effect of nitroglycerin on arterial blood gases and hemodynamics in a group of patients with coronary heart disease. They examined 21 patients. Thirteen of these patients received morphine and scopolamine as a premedication when sublingual nitroglycerin was given. Eight patients did not receive premedication. In the 13 patients who received premedication, the Pao₂ level decreased from a mean of 65+13 to 55+11 mm Hg following the administration of nitroglycerin. In the eight patients who did not receive premedication, the mean value of 78±10 mm Hg decreased to 64±8 mm Hg. In both groups pH and Pco₂ values did not change. The study provided conclusive evidence that sublingual nitroglycerin adversely