ANALYSIS OF THE KINETICS OF PERITONEAL ADHESION FORMATION IN THE RAT AND EVALUATION OF POTENTIAL ANTIADHESIVE AGENTS

Background. Peritoneal adhesions continue to be a significant cause of postoperative complications. Elucidating the origin of these adhesion s has been hampered by the lack of a reproducible animal model. The pu rpose of this study was to create a standardized model in which a sing le, specific adhesion could be objectively measured. With this model t he kinetics of adhesion formation were then evaluated. A variety of po tential antiadhesive agents were then tested and compared. Methods. In this study a reproducible, quantitative rat model was developed that used uniform defects on the peritoneal wall and cecal surface. The res ulting adhesions were subsequently scored, and their strength was meas ured with a tensiometer. An evaluation of the kinetics of peritoneal a dhesion formation was obtained by using a timed removal of silicone el astomer 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 absorba ble barrier of specially knitted material composed of oxidized regener ated cellulose; fibrin sealant; silicone elastomer film; and expanded polytetrafluoroethylene membrane. Results. Evaluation of the kinetics of peritoneal adhesion formation indicated that the susceptibility for adhesion formation was significantly decreased or eliminated after th e first 36 hours. Evaluation of antiadhesion agents indicated that the magnitude of adhesion prevention was directly proportional to the age nt's ability to remain at the site of injury during the critical perio d of adhesion formation. Permanent barriers (silicone elastomer film, expanded polytetrafluoroethylene membrane) provided the greatest antia dhesion effect but were not believed to be ideal agents because they r emained at the site of injury well after the critical period of adhesi on formation. The incidence of adhesion formation for the other agents was as follows: control (34 of 34), Ringer's lactate (12 of 12), abso rbable barrier of knitted cellulose (10 of 10), 32% dextran 70 (8 of 1 2), 1% carboxymethylcellulose (6 of 12), fibrin sealant (4 of 9), and 2% carboxymethylcellulose (4 of 12). Conclusions. The efficacy of anti adhesion agents appears to be related to the agent's viscosity, abilit y to coat the wound surface, and residence time at the site of injury. In this rat model art agent that remained on the injured surfaces for at least 36 hours after injury appeared to be more effective in reduc ing adhesion formation than art agent with a shorter residence time.