Experimental pathology of intravenous Polyurethane cannulae containing disinfectant

Cannula tubing (1·6 mm external, 1 mm internal diameter) manufactured from medical grade polyurethane containing 2% 2,4,4′-trichloro-2′-hydroxydiphenylether (‘Irgasan’, Ciba-Geigy) was found to have no effect other than that seen with control (‘Irgasan’-free) tubing in the following test systems: (i) haemolysis, (ii) endothelial cell cultures, (iii) paravertebral muscle of rabbits, (iv) jugular vein of rabbits, (v) cannulation of baboons and (vi) clotting times of human platelet-rich plasma. However, the results from (iv) showed a significant amount of damage from both impregnated and control cannulae and (v) showed that all detectable ‘Irgasan’ had been eluted from the portions of tubing retained within the animal before the end of the experiment, more rapidly than predicted from in-vitro studies. The rate of elution of ‘Irgasan’ in vivo needs to be further investigated, and consideration should be given to developing a plastic-disinfectant combination with a slower rate of loss of disinfectant.