Peritoneal morphological changes due to pneumoperitoneum: the effect of intra-abdominal pressure

Carbon dioxide (CO2) used in laparoscopy evokes local and systemic effects. This study was designed to evaluate the histopathologic morphologic changes due to CO2 and air insufflation, at different pressure levels, on visceral and parietal peritoneum in rats.

A total of 56 rats were object of the study, randomly divided into five groups. Pneumoperitoneum (PN) was maintained for 30 minutes, at a flow rate of 0.5 L/min and at a pressure of 10 and 6 mm Hg with CO2 (group S1-S2, n = 32) and filtered air (group A1-A2, n = 16). Only anesthesia was performed in the fifth group (group C, n = 8). Peritoneal samples were obtained 24 hours later for blinded histological evaluation. A grading system was adopted to evaluate histological peritoneal changes (0, no change; 1, mild; 2, moderate; and 3, severe) such as mesothelial aspect, inflammatory response, edema, and hemorrhage. The score reflected the severity of damage and was calculated by the sum of the degree evaluated separately. Values were compared with the analysis of variance analysis.

CO2 and air insufflation caused reactive mesothelial cells and peritoneal inflammation of different degrees depending on the level of intra-abdominal pressure (IAP) and type of gas. These modifications were absent in group C and were less evident in low pressure S2 group with respect to S1 and A1-A2 groups. The average values of histopathologic peritoneal score showed significant differences between S2 (11.5) versus S1 groups (16.83) with respect to A groups (A1 = 27.83; A2 = 20.5) and compared with the controls (C = 2.5).

Our data confirm that PN affects the peritoneal integrity. The grades of morphological peritoneal changes are related to the level of IAP. Low CO2 pressure causes minor peritoneal changes with respect to high pressure and air insufflation.