Pigs are not a reliable experimental model in the study of the haemodynamic and respiratory effects of CO2 pneumoperitoneum

Background: Haemodynamic and respiratory effects of a CO 2 pneumoperitoneum (intra‐abdominal pressure = 12 mmHg) associated to a head‐up position(15°) were studied in 20 pigs using a Swan‐Ganz catheter and the Single Breath Test for CO 2 . The pneumoperitoneum induced a moderate rise in mean arterial pressure (+17%) ( P <0.001) without any variation in heart rate, cardiac output and systemic vascular resistances. Results: The following respiratory effects were observed: an increase in P a CO 2 (+20%) ( P <0.001), P E' CO2 (+31%) ( P <0.001), expired volume of CO 2 (+28%) ( P <0.001), arterial to end‐tidal CO 2 gradient (+80%) ( P <0.001) and alveolar dead space (+40%) ( P <0.001) occured. Alveolar ventilation remained stable. Finally and contrary to healthy human patient, intraperitoneal CO 2 insufflation in pig induced slight haemodynamic changes and major respiratory modifications. Conclusion: Thus, our data do not support the conclusion that the pig is a reliable experimental model for studying the pathophysiology of CO 2 pneumoperitoneum‐induced changes in haemodynamic and respiratory parameters, in human patients.