CHRONIC LOADING OF POLYPROPYLENE SUTURES - IMPLICATIONS FOR BREAKAGE AFTER CAROTID ENDARTERECTOMY

This study compared the breaking force of acutely and chronically load ed 6-0 and 5-0 polypropylene sutures, It also examined the effect of g raded injuries on those sutures, Studies were performed on 134 6-0 and 5-0 polypropylene sutures subjected to acute loads, 312 6-0 and 5-0 s utures subjected to chronic loads, and 377 6-0 sutures subjected to qu antitative ''pinches'' with DeBakey forceps to produce graded injuries before chronic loading, The lowest acute breaking force for 6-0 polyp ropylene was 192 g. This occurred in 1.3% of acutely loaded sutures, T he single lowest chronic breaking force for 6-0 sutures was between 15 0 and 175 g, occurring in 5% of chronically loaded sutures, Thus, chro nically loaded sutures are more likely to break than are acutely loade d ones, All of the chronically loaded sutures broke within the first 4 8 hr of loading, resembling the time of breakage in patients, The lowe st chronic breaking force for 5-0 sutures was 300 g, 71% greater than the 175 g for 6-0 sutures, Graded pinches of 6-0 sutures with DeBakey forceps increased the risk of breakage with chronic loads even more. A ll of the above data were related to the forces imposed upon a suture when it is used to close a carotid arteriotomy. Safety ratios were low er for chronically loaded 6-0 sutures than for acutely loaded 6-0 sutu res or for chronically loaded 5-0 sutures, When used to close a caroti d arteriotomy, 6-0 polypropylene has an acceptable safety ratio with r espect to acute loads, but this is markedly reduced with chronic loadi ng, producing a small but finite risk of breakage, The safety ratio ma y be reduced to dangerously low levels if the suture is handled improp erly, Use of 5-0 sutures would greatly increase the safety ratio of th e suture line, both acutely and chronically, when polypropylene is use d to close a carotid arteriotomy, (C) 1996 Academic Press, Inc.