Combined inhalation of nitric oxide and oxygen in chronic obstructive pulmonary disease

Inhaled nitric oxide (NO) has been shown to reduce the mean pulmonary artery pressure (mPAP) and to improve Pa-O2 in patients with acute respiratory failure undergoing oxygen (O-2) therapy. However, inhaled NO reduced pulmonary hypertension without improving Pa-O2 in patients with chronic obstructive pulmonary disease (COPE). This study was intended to compare the hemodynamic and gas exchange responses during inhalation of NO or O-2 With those observed during the combined inhalation of NO and O-2 in 10 spontaneously breathing COPD patients. Hemodynamic and blood gas parameters were measured after breathing: (1) room air; (2) NO added to room air; (3) O-2 (1 L/min); or (4) NO and O-2. During inhalation of 2 ppm NO added to room air, the mPAP (23.1 +/- 2.5 versus 20.6 +/- 2.2 mm Hg) and the pulmonary vascular resistance (PVR) (434 +/- 70 versus 378 +/- 50 dyne s/cm(5)) were significantly (p < 0.05) lower than those measured with room air. However, the values of Pa-O2 did not improve. The combined inhalation of NO and O-2 was associated not only with a significant (p < 0.05) decrease of mPAP (21.4 +/- 2.3 versus 19.7 +/- 1.8 mm Hg) and PVR (431 +/- 72 versus 370 +/- 44 dyne s/cm(5)), but also with a remarkable improvement (p < 0.05) in the values of Pa-O2 (91.4 +/- 6.6 versus 111.5 +/- 7.8 mm Hg) as compared with values obtained during the inhalation of O-2 alone. These findings suggest that combined therapy with NO and O-2 may constitute an alternative approach to treating patients with COPD and pulmonary hypertension.