Pathological findings in silicone spallation in vitro studies.

Silicone pump head tubings were subjected to mechanical stress under conditions which simulated hemodialysis. Examination by scanning electron microscopy revealed evidence of abrasion on the internal surface of the tubing following 5 h of normal use. Damage was extensive after 20 h and large splits and lacerations were present on the internal surface after 96 h of pumping. Atomic absorption spectrometric analysis of the circulated blood provided confirmatory evidence of spallation, and concentrations of polydimethylsiloxane (silicone) rose in parallel with the duration of use. While spallation has previously been demonstrated from polyvinyl chloride, latex and silicone tubings during the faster flow rates of cardiopulmonary bypass, this report is the first to show silicone spallation at flow rates obtained during hemodialysis.