Effects of nitric oxide inhalation after pulmonary thromboendarterectomy for chronic pulmonary thromboembolism.

STUDY OBJECTIVES To examine the hypothesis that nitric oxide (NO) inhalation improves hemodynamics and gas exchange in patients with chronic pulmonary thromboembolism after pulmonary thromboendarterectomy. DESIGN Prospective crossover clinical study. SETTING : Surgical ICU in a national education and research hospital. PATIENTS : Seven patients (mean age +/- SD, 54 +/- 11 years) who underwent elective pulmonary thromboendarterectomy for chronic pulmonary thromboembolism. INTERVENTIONS Patients breathed 20 parts per million of NO gas for 30 min at 12-h intervals until extubation of the trachea. MEASUREMENTS AND RESULTS Hemodynamics and arterial blood gas levels were analyzed before, during, and after NO inhalation. Waveform of pulmonary artery pressure (PAP) was evaluated using fractional pulse pressure (PPf): (systolic PAP - diastolic PAP)/mean PAP. After surgery, pulmonary vascular resistance decreased, PPf decreased, and cardiac index increased significantly. At the first trial, NO inhalation resulted in a slight improvement in arterial oxygen tension (from 173 +/- 33 to 196 +/- 44 mm Hg; p < 0.05), while hemodynamics did not change significantly. Twelve hours later, NO inhalation decreased pulmonary vascular resistance index (from 312 +/- 98 to 277 +/- 93 dyne.s. cm(-5)/m(2); p < 0.01), while the change in oxygenation was not significant. CONCLUSIONS Immediately after pulmonary thromboendarterectomy for chronic pulmonary thromboembolism, NO inhalation improved oxygenation; at 12 h after surgery, NO inhalation resulted in decreased pulmonary vascular resistance, although both changes were small.