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.