Background: It has been shown repeatedly that laparoscopic cholecystectomy using pneumoperitoneum (CO2 insufflation) may be associated with increased cardiac filling pressures and an increase in blood pressure and systemic vascular resistance. In the present study, the effects on the central circulation during abdominal wall lift (a gasless method of laparoscopic cholecystectomy) were compared with those during pneumoperitoneum. The study was also aimed at elucidating the relationships between the central filling pressures and the intrathoracic pressure.
Methods: Twenty patients (ASA I), scheduled for laparoscopic cholecystectomy, were randomised into two groups, pneumoperitoneum or abdominal wall lift. Measurements were made by arterial and pulmonary arterial catheterization before and during pneumoperitoneum or abdominal wall lift with the patient in the horizontal position. Measurements were repeated after head-up tilting the patients as well as after 30 min head-up tilt. The intrathoracic pressure was monitored in the horizontal position before and during intervention using an intraesophageal balloon.
Results: After pneumoperitoneum or abdominal wall lifting there were significant differences between the two groups regarding MAP, SVR, CVP, CI, and SV. Analogous to previous studies, in the pneumoperitoneum group CVP, PCWP, MPAP, and MAP as well as SVR were increased after CO2 insufflation (P < 0.01), while CI and SV were not affected. In contrast, in the abdominal wall lift group, CI and SV were significantly increased (P < 0.01), as was MAP (P < 0.01), while CVP, PCWP, MPAP, and SVR were not significantly affected. There was a significant difference in intraesophageal pressure between the two groups. In the pneumoperitoneum group, the intraesophageal pressure was increased by insufflation (P < 0.01) while, in the abdominal wall lift group, it was unaffected. In the pneumoperitoneum group the mean increases in cardiac filling pressures were of the same magnitude as the mean increase in the intraesophageal pressure.
Conclusions: In healthy patients, abdominal wall lift increased cardiac index while pneumoperitoneum did not. Cardiac filling pressures and systemic vascular resistance were increased by pneumoperitoneum but unaffected by abdominal wall lift. The recorded elevated cardiac filling pressures during pneumoperitoneum may be only a reflection of the increased intra-abdominal pressure.