Effect of PEEP and inhaled nitric oxide on pulmonary gas exchange during gaseous and partial liquid ventilation with small volumes of perfluorocarbon

Background: Partial liquid ventilation, positive end-expiratory pressure (P EEP) and inhaled nitric oxide (NO) can improve ventilation/perfusion mismat ch in acute lung injury (ALI). The aim of the present study was to compare gas exchange and hemodynamics in experimental AU during gaseous and partial liquid ventilation at two different levels of PEEP, with and without the i nhalation of nitric oxide. Methods: Seven pigs (24+/-2 kg BW) were surfactant-depleted by repeated lun g lavage with saline. Gas exchange and hemodynamic parameters were assessed in all animals during gaseous and subsequent partial liquid ventilation at two levels of PEEP (5 and 15 cmH(2)O) and intermittent inhalation of 10 pp m NO. Results: Arterial oxygenation increased significantly with a simultaneous d ecrease in cardiac output when PEEP 15 cmH(2)O was applied during gaseous a nd partial liquid ventilation. All other hemodynamic parameters revealed no relevant changes. Inhalation of NO and instillation of perfluorocarbon had no additive effects on pulmonary gas exchange when compared to PEEP 15 cmH (2)O alone. Conclusion: In experimental lung injury, improvements in gas exchange are m ost distinct during mechanical ventilation with PEEP 15 cmH(2)O without sig nificantly impairing hemodynamics. Partial liquid ventilation and inhaled N O did not cause an additive increase of PaO2. (C) Acta Anaesthesiologica Scandinavica 44 (2000).