S190 Hemodynamic alterations after pneumoperitoneum (PMOP) during laparoscopic procedures have been widely investigated in the recent past. Increasing number of the authors are reporting the absence of major hemodynamic changes [1]. However there is to date no study to evaluate hemodynamic changes during the insufflation. The aim of our study was to assess the effect of posture and PMOP during insufflation at different flow rates. METHODS: 10 pigs (weight 20-25 kg) were anesthetized with propofol, sufentanil and pancuronium. Mechanical ventilation (FiO2 0.6) maintained arterial pH, PO (2) and PCO2 in normal range. Monitored variables included: heart rate (HR), mean arterial pressure (MAP), airways pressure (PIP), tidal volume (VT) and aortic output (AO) using a trans-esophageal echo-Doppler ultrasound allowing a continuous monitoring (Dynemo 3000-Sometec, Paris). The PMOP involved intraperitoneal insufflation of CO2 to an intra-abdominal pressure of 15 mmHg at different flow rates (8L/min, 4L/min, 2L/min) in supine position (5 pigs) or in Trendelenburg position (5 pigs). Data were collected at baseline (T1), at the end of insufflation (T2) and 5 min after insufflation (T3) and were analyzed using ANOVA for repeated measures. RESULTS: expressed as mean +/- SD. Hemodynamic variations at the end of insufflation with different outputs (8L/min, 4L/min, 2L/min) in supine position (Table 1) and Trendelenburg (Table 2). *: P < 0.005 vs T1Table 1Table 2DISCUSSION: The current study using a continuous hemodynamic monitoring demonstrates that AO always increases during insufflation of the PMOP. This increase was higher when insufflation output was high in supine position. This suggests that the increase in AO is a consequence of a transitory increase in venous return to right ventricle in response to the insufflation. Frank-Starling law may explain that a lower insufflation output (4 L/min or 2L/min) induces a lower increase in venous return allowing an adaptation of cardiac output. 5 min after insufflation AO returned to basal values. CONCLUSIONS: The transitory increase in AO during a pneumoperitoneum depends on the speed and output of insufflation and position. These results suggest that the increase in preload by increase in venous return is involved in the phenomenon. These findings suggest that hemodynamic tolerance could be improved when pneumoperitoneum is created with a low insufflation output in supine position.