The effect of fluid overload in the presence of an epidural on the strength of colonic anastomoses

Background: Despite the beneficial effects of epidurals in intra-abdominal surgery, the incidence of anastomotic leak remains controversial when used. Moreover, studies have also shown that fluid overload may be deleterious to anastomoses. The purpose of this paper is to evaluate the effects of varying intraoperative fluid protocols, in the presence of an epidural, on the burst pressure strength of colonic anastomoses.

Methods: An epidural was installed in 18 rabbits, divided into three groups. Group 1 received 30 mL/kg/h Ringer's lactate, Group 2 received 100 mL/kg/h Ringer's lactate, and Group 3 received 30 mL/kg/h Pentaspan. Two colo-colonic anastomoses were performed per rabbit. On postoperative day 7 the anastomoses were resected and their burst pressures measured as a surrogate for anastomotic leak.

Results: When comparing the average burst pressures of all three groups, there was a significant difference (P = 0.04). The anastomoses in the 100 mL/kg/h Ringer's lactate group were shown to be the weakest, with 64% of the anastomoses having burst under 120 mm Hg. The rabbits hydrated with Pentaspan had the highest strength, with no anastomoses bursting under 120 mm Hg. This translated into significant burst pressure differences (P = 0.02) between Group 2 and Group 3.

Conclusion: These results suggest that fluid overload with a crystalloid, in the presence of an epidural, may be deleterious to the healing of colonic anastomoses, creating a higher risk of anastomotic leak. Intraoperative resuscitation should thus focus on goal-directed euvolemia with appropriate amounts of colloids and/or crystalloids to prevent the risk of weakening anastomoses, especially in patients with epidurals.