Compression injury of the circular stapler for gastrointestinal end-to-end anastomosis: preliminary in-vitro study

PURPOSE: This preliminary in-vitro study was designed to evaluate the risk factors of compression injury from use of a circular stapler for end-to-end anastomosis. METHODS: Transparent collagen plates were prepared in dry and wet conditions. Physical properties of collagen plates and porcine colon tissue were examined using a rheometer. Adjustable and fixed-type circular staplers were applied on the collagen plates and the gap distance and compressive pressure were measured during anvil approximation. Tissue injury was evaluated using a compression injury scale. Compression properties were accessed to optimal or overcompression based on gap distance. RESULTS: Unacceptable injuries were rarely observed on the dry collagens, regardless of compression device. In the adjustable compression, the compressibility ratio was similar between dry and wet collagen. Overcompression and unacceptable injury increased on the wet collagens. In the fixed compression, the compressibility ratio increased significantly and unacceptable injuries were observed in more than 50% of wet collagens. Peak pressure was significantly higher in the fixed-compression types than those of adjustable type. On bivariate correlation analysis, fixed-compression type and wet collagens were respectively associated with overcompression. On multivariate analysis, edematous collagen condition was the most important risk factor and proximal anvil side, fixed compression type, and overcompression were also independent risk factors for unacceptable compression injury. CONCLUSION: In the edematous tissue condition, unintentional overcompression could be increased and result in tissue injury on the compression line of the circular stapler.