Electron-microscopic alterations of the peritoneum after both cold and heated carbon dioxide pneumoperitoneum

Background. Carbon-dioxide (CO2) is used universally as an insufflation agent to create a laparoscopic pneumoperitoneum. In this study, we aimed to examine the electron and light microscopic alterations of the peritoneum after both cold-dry and heated-humidified CO, pneumoperitoneum. Materials and methods. Thirty male Sprague-Dawley rats were used in this study. The rats were separated into three groups each comprising 10 rats. Group-I: (Control group): Gas insufflation was not applied to these animals. Group-II: These animals received standard cold-dry (21 degrees C, 2% relative humidity) CO2. Group-III: These animals received heated-humidified (40 degrees C, 98% relative humidity) CO2. In groups II and III, peritoneal gas was emptied 2 h after pneumoperitoneum. application. All rats were killed after 12 h. Peritoneal samples were examined both by scanning electron and light microscopy by two different pathologists who were not aware of the groups. Results. According to light microscopic examination; in group II and III, cellular response (increased lymphocyte) was significantly higher than the control group (P < 0.01). Similarly, in group II cellular response was significantly higher than group Ill. (P < 0.01). There was no difference in increased capillarity among all groups. (P > 0.05). According to scanning electron microscopic examination, in group I, normal peritoneum was covered by a sheet of flat mesothelial cells densely covered with microvilli. No intercellulary clefts and no free basal lamina were detected. In group II, drastic alterations of the surface layer were seen. The mesothelial cells had extreme desquamation, and the basal membrane was clearly visible. In group III, the mesothelial cells had bulged up to the surface layer and retracted. Intercellulary clefts become visible, but the basal lamina was not seen. Conclusions. Electron and light microscopic examination revealed that heated-humidified CO results in less peritoneal alteration than cold-dry CO2. Accordingly, we believe that heated-humidified CO2 is more suitable for pneumoperitoneum. application in laparoscopic surgery especially in selected cases. (c) 2005 EIsevier Inc. All rights reserved.