Mechanism of nitroglycerin-induced hypoxemia.

We and others have previously demonstrated a consistent significant decline in arterial oxygen tension (PaO2) after sublingual nitroglycerin in premedicated and unpremedicated patients both with and without coronary artery disease and/or obstructive ventilatory disease. Thus, in our 19 patients, PaO2 fell by an average of 17% (12 mm Hg), mean systemic arterial pressure by 19% (17 mm Hg), pulmonary arterial pressure by 38% (6 mm Hg), pulmonary arterial occlusive pressure by 62% (5.3 mm Hg), and cardiac index by 16% (0.

Arterial hypoxemia following the administration of sublingual nitroglycerin.

The effect of nitroglycerin on arterial blood gases and cardiovascular hemodynamics were studied in patients with coronary artery disease. In 13 premedicated patients blood gases and cardiovascular hemodynamics were studied before and 10 minutes after sublingual nitroglycerin (0.6 mg).

A sensitive five-breath N2 washout test of distribution of ventilation.

The amount of nitrogen eliminated in the first five breaths after start of oxygen breathing was compared with the amount that would be removed in these breaths, if alveolar mixing were uniform. The ratio of these two amounts is a measure of the degree of unevenness of ventilation; it was determined in 41 nonsmokers, 22 heavy smokers, and 6 patients with chronic obstructive pulmonary disease. The "five-breath index" (ratio x 100) in the nonsmokers ranged between 90 and 100.