ROLLER-PUMP INDUCED TUBING WEAR OF POLYVINYLCHLORIDE AND SILICONE-RUBBER TUBING - PHASE-CONTRAST AND SCANNING ELECTRON-MICROSCOPIC STUDIES

Tubing wear and spallation have long been recognized as complications of roller pumps used in cardiopulmonary bypass (CPB) although the repo rted results of studies of polyvinylchloride (PVC) and silicone rubber tubing wear are still controversial. We conducted phase contrast micr oscope (PCM) and scanning electron microscope (SEM) studies of roller pump induced tubing wear. A closed CPB circuit was constructed, and bo th PVC and silicons rubber tubing (1/2 inch internal diameter [ID]) we re tested under normal and right occlusions of a dual roller pump at a typical CPB flow rate (4,500 ml/min) for 1, 2, 4, and 6 h in quintet. After each pump run, the tubing was removed. It was first examined wi th PCM, and suspicious portions were then analyzed in detail using SEM . In silicone rubber tubing of longer running time, the external diame ter often decreased. Wear was invariably found on the luminal surfaces at the junction of the inner and outer walls of both the PVC and sili cone rubber tubing with no significant differences between normal and tight occlusion. The grooves in the PVC tubing were narrow and continu ous with occasional deep cracks in the tubing after more than 3 h of p ump run. The grooves in the silicone rubber tubing were wide and often interrupted with occasional V-shaped elevated areas. Craters of less than 50 mu occurred sporadically in both types of tubing. Neither PVC nor silicone rubber tubing offers advantages in terms of roller pump i nduced tubing wear and spallation.