Arterial hypoxemia following the administration of sublingual nitroglycerin in patients with ischemic heart disease and pneumonia.

Nitroglycerin (Ng) is a potent and short-acting coronary and systemic vasodilator, widely used in anginal pain treatment. When given to patients with pneumonia or chronic lung disease, Ng was found to cause a further decrease in arterial oxygen tension (PaO2) by increased perfusion of poorly ventilated territories in the lungs. In order to investigate the potential hazard in Ng decreasing the PaO2 in ischemic heart disease patients, who develop acute pneumonia, we administered 0.4 mg Ng sublingually to 11 patients who suffered concomitantly from ischemic heart disease and acute pneumonia. Arterial blood gases were monitored before, 2, 5 and 10 min following Ng administration, as well as a standard 12-lead electrocardiogram that was monitored as the same time. 8 out of the 11 patients showed a decrease in PaO2 which was mild to moderate, during the study period of time, none of them showed an increase, and there was tendency for the lower (less than 60 mm Hg) initial PaO2 to show a lesser decrease in the PaO2 in comparison to the higher (greater than 60 mm Hg) initial PaO2. There was no statistical significant correlation between the decrease in PaO2 and patients' age, sex, coexisting chronic obstructive lung disease and severity of systemic heart failure. Our conclusion is that the hazard in lowering PaO2 by Ng in ischemic heart disease patients who develop acute pneumonia is minimal, but the drug should be used with caution.