The effect of autoclave resterilisation on polyester vascular grafts

Objectives: polyester grafts are expensive, single-use items. Some manufact urers of uncoated, woven grafts include instructions for autoclave resteril isation to be performed at the surgeon's own request. Others warn against s uch manipulation. Theoretically, the glass transition point of polyester at 70-80 degrees C and the possible acceleration of hydrolysis suggest that a utoclave resterilisation at 135 degrees C might be a problem. Materials and methods: a DeBakey(R) Soft Woven Dracon(R) Vascular Prosthesi s (Bard(R)) and a Woven Double Velour Dacron(R) Graft (Meadox(R)) were auto clave-resterilised 0 to 20 times, having been weighed before and after ster ilisation. Tactile testing was performed. Mechanical properties were examin ed by probe puncture and single-filament testing, the surface was examined by scanning electron microscopy and the degree of hydrolysis by infra-red s pectroscopy. Results: tactile testing revealed a change of feeling with increasing cycle s of resterilisation. Investigation of weight, textile strength, single-fil ament strength, electron microscopy of the surface and infra-red spectrosco py showed no change of the material. Conclusions: changes felt are presumably a surface phenomenon, not measurab ly affecting strength or chemistry of material after autoclave resterilisat ion. We therefore feel that it is safe to use once-autoclave-resterilised s urplus uncoated polyester Smps, provided that sterility is guaranteed.