Inhaled nitric oxide during partial liquid ventilation shifts pulmonary blood flow to the non-dependent lung regions

Objective: To elucidate the change in pulmonary blood flow brought about by nitric oxide (NO) inhalation during partial liquid ventilation (PLV).¶Design: Prospective, controlled study.¶Setting: A research laboratory at a university medical center.¶Subjects: Fourteen Japanese white rabbits (3.2 ± 0.05 kg body weight).¶Interventions: Animals were mechanically ventilated in the right decubitus position. Following saline lung lavage, PLV was started with perflubron (15 ml/kg). In the NO group (n = 7), PLV was supplemented by a 30-min challenge of NO inhalation (10 ppm) from 30 min after the initiation of PLV. In the control group (n = 7), PLV was continued for 60 min.¶Measurements and main results: For the pulmonary blood flow analysis, colored microspheres were administered from the right atrium at 30 min (TPLV1) and 60 min (TPLV2) after the initiation of PLV. The percentage of the left lung blood flow in the total pulmonary blood flow (%QL/QT) was significantly increased by NO inhalation in the NO group (p = 0.0164), while that in the control group was significantly decreased during the same period (p = 0.0107). PaO2 in the NO group was significantly increased by NO inhalation (p = 0.0153), but not in the control group (p = 0.7911).¶Conclusion: Inhaled NO during PLV shifted the pulmonary blood flow to the non-dependent region and improved pulmonary gas exchange. This result suggested that inhaled NO took effect predominantly in the non-dependent region during PLV.