[Low dose inhalation of nitric oxide in chronic obstructive pulmonary diseases]

We studied the effect of inhalation of various concentrations of nitric oxide (NO)(2 ppm, 5 ppm, and 10 ppm) on the pulmonary circulation and on arterial oxygenation in 11 patients with stable chronic obstructive pulmonary disease. Inhalation of 2 ppm of NO resulted in values of mean pulmonary arterial pressure significantly lower than those measured while breathing room air only (24.1 +/- 1.7 vs 20.7 +/- 1.7 mmHg, p < 0.00001). The decrease in pulmonary artery pressure associated with inhalation of 2 ppm NO was only slightly less than the decrease associated with 10 ppm; the difference between the two was not considered to be clinically relevant. The pulmonary vascular resistance was significantly lower during inhalation of 2 ppm NO than during inhalation of room air only (495 +/- 40 vs 382 +/- 34 dyne.sec/cm5, p < 0.00001); the effects of inhaling 2 ppm and 10 ppm did not differ significantly. the partial pressure of oxygen in arterial blood was significantly lower after inhalation of 2 ppm NO than of baseline (61.1 +/- 2.3 vs 57.6 +/- 2.2 mmHg, p < 0.01). These results show that inhalation of NO worsens arterial oxygenation in patients with chronic obstructive pulmonary disease.