Laparotomy causes loss of peritoneal mesothelium prevented by humidified CO₂ insufflation in rats

Avoiding tissue desiccation is a common recommendation to reduce postoperative complications following open abdominal surgery, although difficult to achieve delicately without damaging the peritoneal mesothelium. Insufflation of humidified-warm CO₂ into the abdomen during open abdominal surgery is proposed as an invisible, effortless way to prevent desiccation. We hypothesized that desiccation during open abdominal surgery would cause loss of peritoneal mesothelium that would be prevented by insufflation of humidified-warm CO₂.

Nine Wistar rats were assigned to 1 h of anesthesia only, laparotomy only, or laparotomy with insufflation of humidified-warm CO₂. Twelve hours after treatment, rats were euthanized and tissue samples were excised. Scanning electron microscopy (SEM) and light microscopy (LM) images of visceral and parietal peritoneum were scored by two independent, blinded examiners for loss of mesothelium and other indications of inflammation, including measurement of apoptosis by detection of DNA cleavage.

Loss of peritoneal mesothelium was found in peritoneum exposed to laparotomy only (SEM: P = 0.002; LM: P = 0.01), and mesothelial loss was reduced by humidified-warm CO₂ (SEM: P < 0.001; LM P = 0.004). Similarly, DNA cleavage was significantly higher on the peritoneal surface following laparotomy only, compared with anesthesia only (P = 0.0055) and laparotomy with humidified-warm CO₂ insufflation (P = 0.0003).

In a rat model, exposing the peritoneal mesothelial to conditions that replicate minimum recommended air flow within an operating room causes inadvertent loss of mesothelium and signs of inflammation that can be prevented by insufflating humidified-warm CO₂ into the open abdominal cavity.