Development of thrombophlebitis in peripheral veins with Vialon and PTFE-Teflon cannulas: a double-blind, randomised, controlled trial.

A series of 54 normal subjects were randomised to have either a Vialon or a PTFE-Teflon peripheral vein cannula inserted in a vein in each forearm to observe the development of thrombophlebitis. Cannulas were inspected twice daily for up to 5 days to observe the development of three signs, erythema, oedema or hardness and one symptom, pain. Each sign and symptom was recorded twice daily at three points, the cannula insertion site, the mid-point of the cannula and the cannula tip. The degree of change was recorded as less than 1, 1-2 and greater than 2 cm. Any cannula causing any sign greater than 2 cm was removed. By the end of the study over 40% of both types of cannula had been removed. There were no significant differences between the numbers of each type of cannula removed at any time point throughout the duration of the study. There were no significant differences in the amounts of erythema or hardness, but minimally increased swelling was observed at the mid-point of the PTFE-Teflon cannulas (P = 0.022). Despite the theoretical superiority of Vialon as a cannula material, under controlled conditions there appears to be little difference in its inherent capacity to cause the thrombophlebitis.