The effects of increased intraabdominal pressure on colonic anastomoses

This experimental, randomized, controlled study was designed to investigate the effects of increased intraabdominal pressure (IAP) on colocolic anastomoses. To our knowledge, this is the first study to address this important issue.

For this study, 50 Wistar albino rats were randomized into five groups. The animals in all the groups underwent laparotomy and colocolic anastomosis. The rats in the control group were not subjected to increased IAP. Accordingly, IAP's of 14, 20, 25, and 30 mmHg were established by carbon dioxide insufflation and maintained for 60 min in study groups 1, 2, 3 and 4, respectively. Colocolic anastomosis was realized after these periods of IAP in the study groups. Half of the surviving rats in all the groups were sacrificed on postoperative days 7 and 14 to allow comparison between the control and study groups with respect to their mean body weights, mean anastomosis bursting pressures, and histopathologic characteristics of their anastomosis sites.

The mean body weights of all the groups were comparable at all times during the study. The anastomosis bursting pressures of the animals subjected to increased IAP were lower than that of the control group, with the differences reaching statistical relevance for the animals subjected to an IAP of 20 mmHg or higher on postoperative day 7 (p <0.0005 for study groups 2, 3, and 4 vs the control group) and becoming more pronounced by the day 14 (p <0.0005 for study groups 2, 3, and 4 vs the control group). The anastomosis bursting pressure showed an inverse correlation with IAP. The adequacy of mucosal layer formation at the anastomosis line was lower and the degree of inflammation was higher in the groups exposed to an IAP of 20 mmHg or higher in the control group (p <0.05 for both comparisons among study groups 2, 3 and 4 vs the control group).

An IAP increased to 20 mmHg and higher was found to result in impaired strength and wound healing in colocolic anastomoses, as reflected by the decreased bursting pressure and mucosal layer formation, and by the increased inflammation at the anastomosis sites of animals subjected to high IAP values.