Bursting strength of experimental colonic anastomoses. A methodological study.

This study was performed to evaluate the validity of the bursting strength test of experimental anastomoses. By a combination of measuring the intraluminal physiological pressure during the test procedure with a radiological detection of the anastomosed intestinal segment until disruption it was demonstrated that the bursting pressure is a meaningful parameter since the maximum pressure equals the time of anastomotic leak. At day 6 60% of the tested segments disrupted outside the anastomotic line. This indicates that the bursting strength test is not a valid measure for determining the strength of colonic anastomoses after the 4th to 5th postoperative day. Moreover, the bursting wall tension parameter was evaluated. Assessment of the anastomotic radius demonstrated significant differences when the anastomotic radius at disruption was determined from the amount of inflated contrast compared with the radius detected radiologically. These differences had the effect that the wall tension at burst compared with the wall tension determined from direct radius measurement on day 4 was 61% higher than the wall tension determined from the amount of inflated contrast with no correction for elongation of the tested segment, and 36% higher than the wall tension determined from the amount of inflated contrast and corrected for elongation of the segment. No differences in the bursting strength were found between inflation rates of 2.5 and 5.0 ml.min-1. In conclusion, the bursting strength test is a meaningful parameter since the maximum physiological pressure equals the time of anastomotic radiological disruption, and the bursting pressure is a more exact parameter for measuring the bursting strength than the bursting wall tension.