New Devices and Methods for Long-term Vascular Access for Blood Sampling and Insulin Infusion

Abstract

Studies aimed at quantifying the benefits of infused rather than injected insulin have been impeded by the unavailability of suitable methods for continuous vascular access. We have developed indwelling catheters suitable for the long-term blood sampling as well as insulin infusion. A typical catheter consists of a silicone rubber tube, which terminates with a blunt-point needle. Internal or external reinforcement as well as a removable strain relief fitting protect the area of insertion of the needle. Anchoring of the implanted extravascular portion of the catheter is important and is achieved by special grommets that prevent motion without obstructing the lumen. Methods of catheter assembly as well as implantation in the jugular and portal veins of dogs and jugular veins of humans are described. A total of 34 blood sampling catheters were implanted in 26 beagle dogs: 74% were uncomplicated with a duration of implantation of 18–576 days while 15% and 11%, respectively, failed due to infection or physical damage after an average of 200 days. Thirteen portal infusion catheters were implanted: 62% were functional a mean of 100 days (14–166 days) after implantation while 35% became covered with an endothelial sleeve and had to be removed. Thirty-two peripheral infusion catheters were implanted in dogs: one infection occurred, two catheters were physically damaged, and three were plugged. There were no catheter-related complications in the five adolescent diabetic subjects with such jugular venous catheters studied for an average of 19.5 days and three adult diabetic subjects in whom catheters remained patent for 150–270 days. It is the inherent characteristics of the silicone rubber material as well as the new methods of catheter construction and implantation that virtually eliminate catheter-related problems and that now provide an ideal route of access for long-term intravascular insulin infusion in diabetes mellitus.