Analysis of the kinetics of peritoneal adhesion formation in the rat and evaluation of potential antiadhesive agents

Abstract

Peritoneal adhesions continue to be a significant cause of postoperative complications. Elucidating the origin of these adhesions has been hampered by the lack of a reproducible animal model. The purpose of this study was to create a standardized model in which a single, specific adhesion could be objectively measured. With this model the kinetics of adhesion formation were then evaluated. A variety of potential antiadhesive agents were then tested and compared. In this study a reproducible, quantitative rat model was developed that used uniform defects on the peritoneal wall and cecal surface. The resulting adhesions were subsequently scored, and their strength was measured with a tensiometer. An evaluation of the kinetics of peritoneal adhesion formation was obtained by using a timed removal of silicone elastomer sheeting held between the two injured surfaces. The following antiadhesive agents were evaluated: Ringer's lactate solution; dextran 70 (32%); modified carboxymethylcellulose (1.0% and 2.0%); an absorbable barrier of specially knitted material composed of oxidized regenerated cellulose; fibrin sealant; silicone elastomer film; and expanded polytetrafluoroethylene membrane. Evaluation of the kinetics of peritoneal adhesion formation indicated that the susceptibility for adhesion formation was significantly decreased or eliminated after the first 36 hours. Evaluation of antiadhesion agents indicated that the magnitude of adhesion prevention was directly proportional to the agent's ability to remain at the site of injury during the critical period of adhesion formation. Permanent barriers (silicone elastomer film, expanded polytetrafluoroethylene membrane) provided the greatest antiadhesion effect but were not believed to be ideal agents because they remained at the site of injury well after the critical period of adhesion formation. The incidence of adhesion formation for the other agents was as follows: control (34 of 34), Ringer's lactate (12 of 12), absorbable barrier of knitted cellulose (10 of 10), 32% dextran 70 (8 of 12), 1% carboxymethylcellulose (6 of 12), fibrin sealant (4 of 9), and 2% carboxymethylcellulose (4 of 12). The efficacy of antiadhesion agents appears to be related to the agent's viscosity, ability to coat the wound surface, and residence time at the site of injury. In this rat model an agent that remained on the injured surfaces for at least 36 hours after injury appeared to be more effective in reducing adhesion formation than an agent with a shorter residence time.