Conventional pelviscopic surgery requires pneumoperitoneum with CO₂ gas insufflation and lithotomy-Trendelenburg position. Pneumoperitoneum and Trendelenburg position may influence intraoperative respiratory mechanics in anesthetic management. This study was conducted to investigate the influence of pneumoperitoneum and Trendelenburg position on respiratory compliance and ventilation pressure.

Twenty-five patients scheduled for elective gynecologic laparoscopy were evaluated. The patients had no preexisting lung or heart disease or pathologic lung function. Conventional general anesthesia with thiopental sodium, lidocaine, rocuronium, and sevoflurane was administered. The peak inspiratory pressure, plateau pressure, and end-tidal CO₂ were measured before and after creation of pneumoperitoneum with an intraabdominal pressure of 12 mmHg, then after 10 minutes and 30 minutes in the 20° Trendelenburg position, and after deflation of pneumoperitoneum. The dynamic lung compliance was then calculated.

Following creation of pneumoperitoneum, there was a significant increase in peak inspiratory pressure (6 cmH₂O), plateau pressure (7 cmH₂O), and end-tidal CO₂ (5 mmHg), while dynamic lung compliance decreased by 12 ml/cmH₂O. Overall, the Trendelenburg position induced no significant hemodynamic or pulmonary changes.

The effects of pneumoperitoneum significantly reduced dynamic lung compliance and increased peak inspiratory and plateau pressures. The Tredelenburg position did not change these parameters.