Inhaled nitric oxide (40 ppm) during one-lung ventilation, in the lateral decubitus position, does not decrease pulmonary vascular resistance or improve oxygenation in normal patients.

OBJECTIVES

To determine the effects of inhaled nitric oxide (NO) on venous admixture (Qs/Qt), mean pulmonary artery pressure (MPAP), and pulmonary vascular resistance (PVR) in patients undergoing one-lung ventilation (1LV) in the lateral decubitus position.

DESIGN

Prospective, blinded, crossover.

SETTING

University hospital.

PARTICIPANTS

Six adult patients scheduled for thoracotomy.

INTERVENTIONS

Patients were anesthetized with thoracic epidural lidocaine, intravenous fentanyl, and inhaled isoflurane and were monitored with a systemic and pulmonary artery catheter (PAC). In the lateral decubitus position, the dependent lung was ventilated with 70% oxygen (O2) and 30% nitrogen (N2) for the control 1LV condition. For the experimental 1LV condition, the dependent lung was ventilated with the same gas concentration + NO at 40 ppm. Patients were alternated between the control and the experimental NO (40 ppm) conditions every 15 minutes for as long as the case would allow.

MEASUREMENTS AND MAIN RESULTS

During all conditions, oxygenation, Qs/Qt, and pulmonary and systemic hemodynamics were measured in a double-blinded fashion. The mean PVR during 1LV was 128 +/- 39 (SD) dyne.s.cm(-5). Inhaled NO at 40 ppm did not affect MPAP, PVR, or Qs/Qt.

CONCLUSIONS

Inhaled NO at 40 ppm, during 1LV in the lateral decubitus position, did not significantly decrease MPAP in patients with normal baseline PVR. Oxygenation and Qs/Qt did not change in this setting because MPAP was not altered. At present, interventions other than administration of inhaled NO should be applied to patients with normal PVR who experience hypoxia during one-lung ventilation.