Results with a Catheterless Insulin Delivery Device Implanted in a Pancreatectomized Dog

Summary

Judging from the long-term results we have obtained in our animal experiments with implanted remotely programmable insulin delivery devices, the delivery of insulin via a vascular catheter is for the moment problematic because of the risk of thrombo-embolism. Insulin delivery via an intraperitoneal catheter provides a questionable alternative on account of adhesions due to mechanical irritation of the peritoneum. Another possibility transpired from our postmortem findings in animals with long-term implanted insulin delivery devices manufactured by SIEMENS AG. The subcutaneously implanted pumps were located in a smooth connective-tissue capsule containing approximately 1 ml of serous mucus. It was obvious that we should try to pump the insulin solution directly from the device into this capsule and so dispense with the insulin catheter.

Six months ago, we implanted such a catheterless device - again manufactured by SIEMENS AG - in a totally pancreatectomized dog. The device contains a special insulin preparation stabilized for pumps, at a concentration of 100 or 200 IU/ml. The blood glucose control is good. The insulin infusion profile is very simply. The infusion rate need only be increased for one hour by one step over and above the constant basal rate to offset the rise in glucose after a single daily feed. The reason for this simple insulin infusion profile can be attributed to a delay in insulin absorption from the capsule, a delay which is also encountered with intraperitoneal insulin delivery. After the infusion rate has been increased by a single step over a onehour period, there is a protracted rise in insulin in the peripheral blood for half an hour to one hour, which is then followed by a prolonged drop over the next 4 to 5 hours. The peripheral insulin kinetics after intracapsular insulin delivery are largely identical to those in normal animals after a feed. The peripheral insulin values in normal animals after feed intake are, however, on the whole appreciably lower.

Implantable Insulin Delivery Devices