Background and objective: Ventilation of the lungs with positive end-expiratory pressure during pneumoperitoneum has been shown to improve the arterial partial pressure of oxygen. The implications of spontaneous breathing on pulmonary gas exchange remain unknown in this setting. We therefore sought to examine the influence of pressure-support ventilation with spontaneous breathing on gas exchange during simulated laparoscopy.

Methods: Ten pigs were subjected to pneumoperitoneum at a pressure of 15 cmH2O. Animals received, in a random order, pressure-support and pressure-controlled ventilation for 60 min per mode. Inert gas and haemodynamic measurements were performed before changing to a subsequent mode.

Results: Pressure-support ventilation was more efficient than pressure-controlled ventilation regarding perfusion of normal VA/Q lung areas (78 ± 4% vs. 72 ± 5%) (P < 0.05), alveolar-arterial partial pressure of oxygen difference (9.73 ± 1.3 vs. 11.2 ± 1.2 kPa) and arterial partial pressure of oxygen (14.93 ± 1.6 vs. 13.7 ± 2.0 kPa) (P < 0.05).

Conclusions: Pressure-support ventilation resulted in significantly better gas exchange than pressure-controlled ventilation in this model of simulated laparoscopy.