Insufflation profile and body position influence portal venous blood flow during pneumoperitoneum

Background: We investigated changes in portal venous blood flow (PVBF) during carbon dioxide (CO₂) pneumoperitoneum to evaluate the effects of different insufflation profiles and body positions. Methods: An established rat model was extended by implanting a portal vein flow probe that would enable us to measure PVBF for 60 min [t₀–t₆₀] in animals subjected to a CO₂ pneumoperitoneum with an intraabdominal pressure (IAP) of 9 mmHg. Forty-eight male Sprague-Dawley rats were randomized into the following four experimental and two control groups: decompression group D1 (n = 8), desufflation for 1 min every 14 min; decompression group D2 (n = 8), desufflation for 5 min, after 27 min; position group P1 (n = 8), 35° head-up position; position group P2 (n = 8), 35° head-down position; negative control group C1 (n = 8), no insufflation; positive control group C2 (n = 8), constant IAP of 9 mmHg for 60 min. Results: Pneumoperitoneum and body positions, respectively, reduced PVBF [t₁–t₆₀] significantly (p < 0.001) by 32.0% C2, 32.8% D1, 31.1% D2, 40.8% P1, and 48.5% P2, as compared to PVBF at t₀ in each group. There was a significant difference in PVBF reduction between P1 and P2 and also between C2 and both P1 and P2 (p < 0.04). Conclusions: CO₂ pneumoperitoneum reduces PVBF significantly (>30%). Extreme body positions (35° tilt) significantly intensify PVBF reduction. PVBF reduction is significantly more dramatic in subjects placed in a 35° head-down position. Short desufflation periods did not improve mean PVBF, but it may have beneficial immunological and oncological effects that warrant further investigation.Presented at the annual meeting of the European Association for Endoscopic Surgery (EAES), Lisbon, Portugal, 2002.