Chronic perioperative steroids and colonic anastomotic healing in rats

Objective: To develop a rat model of long-term high-dose perioperative steroids and to evaluate the effects of these steroids on a colonic anastomosis in this model. Design: Prospective randomized. Methods: Twenty-six male Sprague-Dawley rats, weighing 270 to 330 g, were randomized into two groups. The first group (steroid group) (13 rats) received a time-release drug pellet (200 mg cortisone acetate in a 60-day release form) placed in the subcutaneous tissue of the posterior neck for an average daily dose of 3.3 mg. The second group (control group) (13 rats) received a placebo. At 6 weeks, blood cortisol levels were measured, and a colonic anastomosis was performed 2.5 cm distal to the cecum. Steroid group animals also received cortisone acetate (5 mg intramuscularly) immediately before surgery. Colonic bursting strength (mmHg) was measured at the anastomosis site and in the normal distal left colon using a saline infusion system at 8 and 12 days postoperatively. Results: Blood cortisol levels were significantly higher in the rats in the steroid group than in the rats in the control group. The anastomotic bursting strength was significantly lower in the steroid group at Days 8 and 12. The bursting pressure of the unoperated left colon was not significantly different when the groups were compared. Also, in the steroid group, healing of the pellet insertion wounds in the neck was impaired. Conclusion: The time-release drug pellet is a reliable method of administering long-term steroids. Long-term perioperative steroids impaired colonic anastomotic healing, while normal tissue strength (left colon) was not significantly changed.