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.

Background and objective Late postoperative hypoxaemia after upper abdominal surgery is common even among cardiopulmonary healthy patients. Atelectasis may develop after intubation and persist into or reveal a disposition for atelectasis in the postoperative period. Positive end–expiratory pressure (PEEP) eliminates peroperative atelectasis but the effect on perioperative oxygenation is controversial. This study evaluated the effect of peroperative PEEP optimized pulmonary compliance on perioperative oxygenation and complications.

Methods Forty patients assessed by electrocardiography, spirometry, functional residual capacity and diffusion capacity were randomly assigned to receive positive end–expiratory pressure (PEEP) or zero endexpiratory pressure (ZEEP) during surgery. PaO2, SPO2 and complications in the postoperative period were evaluated without knowledge of peroperative PEEP or ZEEP application.

Results Peroperative arterial oxygenation improved for all patients receiving PEEP, mean 2.1 kPa (0.7–3.5 kPa). There was no difference in postoperative median PaO2 between the groups. The differences in the incidence of late prolonged postoperative hypoxaemia and complications were 25% (−5% to 55%) and −1% (−31% to 29%) between the ZEEP and the PEEP group, but were not statistically significant.