Study objectives: To examine the hypothesis that nitric
oxide (NO) inhalation improves hemodynamics and gas exchange in
patients with chronic pulmonary thromboembolism after pulmonary
Design: Prospective crossover
Setting: Surgical ICU in a national
education and research hospital.
patients (mean age ± SD, 54 ± 11 years) who underwent elective
pulmonary thromboendarterectomy for chronic pulmonary
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/m2; 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.