Effect of Upper Abdomen Tissue Manipulation on Adhesion Formation between Injured Areas in a Laparoscopic Mouse Model

Study Objective: These experiments were designed to examine the effect of manipulation during surgery as a cofactor in adhesion formation at trauma sites. Design: Randomized, controlled trial. Canadian Task Force Classification-class 1. Setting: University laboratory research center. Subjects: A standardized laparoscopic mouse model (Balb\c mice 9-10 weeks old) for adhesion formation after opposing bipolar lesions and 60 minutes of carbon-dioxide pneumoperitoneum. In this model adhesions are known to decrease after the addition of 3% of oxygen, dexamethasone, or both. In addition, adhesions decrease with experience (i.e., with a decreasing amount of manipulation during the learning curve). Interventions: A factorial design was used to evaluate the effects of dexamethasone and of adding 3% of oxygen on manipulation-enhanced adhesion formation during a learning curve. Blocks of 4 animals were thus randomized as controls (carbon-dioxide pneumoperitoneum only) or received an additional 3% of oxygen, dexamethasone, or both. In a second experiment, the effects of manipulation on adhesion formation were quantified. In a third experiment we evaluated whether dexamethasone had a specific effect on manipulation-enhanced adhesion formation. Measurements and Main Results: Qualitative and quantitative adhesion scoring 7 days after the intervention. The first experiment confirmed that adhesion formation decreased during the learning curve (p <.0001) and after the addition of dexamethasone whether assessed as the total adhesion score (p <.0001 and p =.0009, respectively) or a quantitative score (p <.0001 and p <.0001, respectively). The second experiment showed that adhesion formation increased by standardized touching and grasping of omentum and bowels (proportion score p =.0059 and p =.0003, respectively) and this effect increased with duration of touching (p =.0301). In the third experiment, dexamethasone was confirmed to decreased adhesion formation (p =.0001) but this effect was not specific for manipulation-enhanced adhesion formation. Conclusion: Manipulation of intraperitoneal organs in the upper abdomen enhances adhesion formation at trauma sites, confirming that the peritoneal cavity is a cofactor in adhesion formation. Dexamethasone decreases adhesion formation but the effect is not specific for manipulation-enhanced adhesion formation.