Comparison of Oxidative Stress Changes in Different Ventilation Strategies During Gynecologic Laparoscopic Surgery

Pneumoperitoneum during laparoscopic procedures greatly impairs splanchnic blood flow due to compression. Increased intra-abdominal pressure may elevate the diaphragm, increase intra-thoracic pressure, reduce functional residual capacity, and thus lead to atelectasis. In a collapsed lung, blood flow is decreased and reperfusion injury may subsequently occur during re-expansion of the lung. This ischemia-reperfusion injury results from the formation of reactive oxygen species (ROS), which are highly reactive intermediates of the oxygen metabolism. When there is an imbalance between ROS generation and removal by antioxidative mechanisms, oxidative stress occurs and eventually causes cellular and organ damage. Oxidative stress mediates tissue injury and may represent an important link between laparoscopy and clinical side effects. Malondialdehyde (MDA) is considered the most reliable marker of oxidative stress in the clinical setting. It is a breakdown product of lipid peroxidation in tissues. An elevated concentration of MDA reflects the level of lipid peroxidation.

Although there is abundant data comparing the effects of VCV and PCV during laparoscopic surgery, the time course of changes in oxidative stress in these two modes has not been elucidated. Therefore, the aim of this study was to compare the alterations of oxidative stress in two different ventilation modes, VCV and PCV, during gynecologic laparoscopic surgery. To this end, the investigators established a prospective randomized clinical study and measured the plasma levels of a lipid peroxidation marker at different stages.

Fifty-two patients of ASA physical status I or II were randomly assigned to receive either VCV or PCV during laparoscopic gynecologic surgery. During the operation, blood gas analysis and ventilation variables were recorded 1 minute before (T1) and 1 hour after (T2) the establishment of CO2 pneumoperitoneum in both groups. Blood samples for MDA measurement were collected at seven points: 1 minute before (T1) and 1 hour after (T2) pneumoperitoneum; at intervals of 30 minutes for 2 hours after the deflation of CO2 (T3~T6); and 24 hours after the deflation of CO2 (T7). The samples were immediately centrifuged (1000g, 10 minutes) and the supernatants were stored at -800C until further analysis, which took place within 1 week. The investigators assessed the quality of recovery from anesthesia using a nine-item quality of recovery score (QoR Score) before operation and 24 hours after the deflation of CO2.