Impact of pressure and gas type on anastomotic wound healing in rats

Laparoscopic techniques in the treatment of various bowel diseases have become more and more popular in today's clinical routine. However, knowledge about the impact of a carbon dioxide (CO(2)) pneumoperitoneum on the quality of healing of the intra-abdominal wound is rare. We therefore investigated the effects of pressure and gas type on anastomosis healing in a rat model.

Laparotomy and twofold ileo-ileal anastomosis was performed in 78 male Sprague Dawley rats. A CO(2) or a helium pneumoperitoneum of 3 mmHg (each, n=18) or of 6 mmHg (each, n=12) was maintained before and after ileo-ileostomy. Rats in the control group ( n=18) received no pneumoperitoneum. Animals were killed after 5 and 10 days. As indicator of bowel function, mean body weights were compared between the groups. One region of the anastomosis was subjected to computerised bursting-pressure measurements, while the second was explanted for subsequent histopathological examinations: collagen synthesis and degradation was determined by the ratio of collagen type I to type III and by the matrix metalloproteinase MMP-13. The extent of new mucosal layer formation was measured in haematoxylin and eosin (H and E)-stained sections.

Alteration in mean body weight and the mean anastomosis bursting pressures did not differ between the groups. Likewise, histological examination revealed no statistically significant differences, either in the values for collagen I/III ratios or in the extent of mucosal proliferation. After 10 days, 6 mmHg helium pneumoperitoneum was associated with a more pronounced expression of MMP-13 than that of controls.

A CO(2) pneumoperitoneum with pressures of 3 mmHg and 6 mmHg was found to have no significant impact upon the healing of anastomosis wounds in rats. Helium pneumoperitoneum offers no advantages over CO(2).