The effect of tissue compression on circular stapler line failure.

BACKGROUND: Anastomotic leak after gastrointestinal anastomosis is a well-known and serious complication, yet there is no standardized approach to reliably create an anastomosis with sufficient mechanical properties to consistently avoid an anastomotic leak. The purpose of this study was to evaluate the relationships among combined tissue thickness, tissue compression, closed staple limb length, and mechanical strength of an anastomosis created with a circular stapler, as measured by maximum intraluminal pressure obtained at the time of leakage.
METHODS: Using 27 porcine stomachs and 27 porcine small-intestine segments, we measured tissue thickness and assessed the tissue compression at three different anvil closure distances created by a circular stapling device. Maximum intraluminal pressure was determined by infusing colored water into the porcine materials and increasing the pressure until leakage from the anastomosis occurred.
RESULTS: Tissue compression increased as the closure distance narrowed between the anvil and circular stapler (p < .0001). A tissue compression of ≥6 PSI correlated strongly with a maximum intraluminal pressure of ≥18 mmHg (43% for <6 PSI vs. 90% for ≥6 PSI; p = .02); tissue compression ≥12 PSI was necessary to obtain an acute maximum intraluminal pressure of ≥22 mmHg in 13 of 15 of our samples (p = .04).
CONCLUSIONS: Maximum intraluminal pressure of an anastomosis in this porcine model correlated most strongly with the compression of the tissue involved in the anastomosis. This experimental model provides a framework for constructing a systematic approach to creating an anastomosis with sufficient mechanical strength. However, this study was not intended to establish the upper range of tissue compression beyond which a permanent tissue injury may occur.