Effects of Pneumoperitoneum on Mean Arterial Pressure and Hypotension Prediction Index Responses During Hemorrhage and Transfusion in a Porcine Model

Background/Objectives: CO2 pneumoperitoneum (PnP) alters hemodynamics during laparoscopic surgery. We examined whether PnP modifies mean arterial pressure (MAP) and hypotension prediction index (HPI) responses to controlled, stepwise hemorrhage and retransfusion in a porcine model. Methods: This exploratory secondary analysis included recordings from three PnP-only pilot animals and nine animals with analyzable data from a randomized crossover experiment involving both PnP and No-PnP conditions. Blood was withdrawn and retransfused in 100 mL increments up to 600 mL per phase under both PnP (15 mmHg) and No-PnP conditions. MAP and HPI were averaged within protocol windows and analyzed using linear mixed-effects models to assess changes across protocol windows, condition-by-window interactions, and paired within-animal differences. Results: Twenty-one hemorrhage–transfusion sets from 12 animals were analyzed, comprising 12 PnP and nine No-PnP sets. MAP decreased and HPI increased overall during hemorrhage, with the opposite pattern observed during retransfusion in both conditions (all protocol-window effects, p < 0.001). No significant condition-by-window interactions were detected during hemorrhage (MAP, p = 0.407; HPI, p = 0.925) or retransfusion (MAP, p = 0.999; HPI, p = 0.910). Within-animal differences did not vary significantly across protocol windows in either phase. Conclusions: No significant PnP-related differences in the patterns of MAP and HPI change were detected in this porcine model. These findings provide experimental context for interpreting MAP and HPI during blood loss in laparoscopic surgery; clinical studies are needed to determine whether HPI adds predictive information beyond MAP.