Correlation of tensile strength with bursting pressure in the evaluation of intestinal anastomosis

Background: Although bursting pressure and tensile strength have long been measured to evaluate anastomotic techniques, it has yet to be clarified whe ther or not they are correlated, what implications they have, and which sho uld be used as a gold standard. Material and Methods: Using an experimental model to estimate pressure and tension in the same colonic anastomosis, th e following variables were measured in 48 rats between days 0 and 14: burst ing pressure (BP); minimal tensile strength (MITS) necessary to break a par t of the anastomosis, and maximal tensile strength (MATS) needed to disrupt the whole anastomosis. Also, circulatory wall tension (CWT) was derived fr om BP and the anastomotic circumference (AC), and longitudinal wall tension (LWT) from MITS and AC. These variables were compared using correlation an d regression analysis. Results: During the lag phase (days less than or equ al to 4) there was poor correlation between pressure-related and tension-re lated variables whereas highly significant correlations were noted in the s ubsequent fibroplastic phase (day greater than or equal to 5). It was shown by regression lines that positive MITS and MATS were expected when BP was zero. Conclusion: Contrary to the previous assumption, no correlation was f ound between BP and tensile strength in the critical postoperative period. Based on our present and previous studies, measurement of MITS is recommend ed to evaluate the healing of colonic anastomosis. Copyright (C) 1999 S. Ka rger AG, Basel.