One year continuous run with a totally implantable insulin infusion pump in a human diabetic.
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Adult↗
Biomedical subjects
K Prestele
Publications and source records attributed to K Prestele.
Total implantation of a remotely controlled insulin minipump in a human insulin-dependent diabetic.
This study reports our first total implantation of an insulin minipump in a severely unstable 23-year-old female insulin-dependent diabetic. The implantable unit includes a stepping motor, a percutaneously refillable insulin reservoir (10 ml, U 100 special insulin), a battery with a life span of one year, and a method for prevention of overdosage. Variable continuous basal and superimposed 1-hour high rates are programmed and checked via an external remote controller. The pump was inserted in the lateral muscles of the abdomen and the insulin delivery catheter terminated in the peritoneal cavity. Excellent glycemic control was reached rapidly and has continued seven months after implantation (mean blood glucose is 123 +/- 62 mg/dl; glycosylated hemoglobin is 7.0 +/- 1.2%), with the unit providing the only source of insulin. The only negative aspects were a chronic lymphorrhea in the first two months, and a need for frequent and laborious insulin refills (every 20 days). Only slight local discomfort was experienced. Thus, although further miniaturization and autonomy are expected, these preliminary results show that with careful instruction and followup, implanted pumps could represent a reliable and safe alternative to conventional insulin therapy for selected diabetics.
Adult↗
Long-term continuous intraperitoneal insulin infusion with an implanted remote-controlled insulin infusion device.
This is a report of the implantation and first 100-day operation using a remote-controlled programmable insulin infusion device in an insulin-dependent diabetic. To prevent insulin aggregation, a special surface-active polymer developed by Hoechst AG, Frankfurt, was used as an additive. Implantation was completed on April 8, 1981, and good metabolic control was reached immediately and has continued to date (July 1981), with this unit providing the only source of insulin. There have been no hypoglycemic attacks. Patient acceptance is very good. The Siemens unit, PFA 01 (external) and DFA 01 (implanted) has proved reliable and precise.
Blood Glucose↗
On-line computation of the stroke volume from the systolic stroke of the thoracic impedance. Part 1: method and automatic evaluation.
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Animals↗
A direct-display oscillation method for measurement of respiratory impedance.
The basic principle of the method described here is derived from a variant of the oscillation method. A reference impedance is connected to the mouth; between these two an oscillating flow is imposed. As a reference impedance we use a flexible tube, which acts as a virtually pure inductance or inertance. Respiration is hardly impeded. The only measured parameter is the alternating pressure in front of the mouth and this is easily picked up by a simple microphone. In contrast to former direct-display methods, the inertia and elasticity of the respiratory gas and the respiratory tract, i.e., airways including lungs and thorax, are also taken into account for the evaluation. The respiratory resistance is studied as a complex parameters, i.e., as an impedance. With the aid of diagrams or via electronic computation circuitry, the direct and continuous display of all impedance components such as its magnitude and phase, resistance, and reactance is possible. They can be read out as a function of time, respiratory flow, or volume.
Airway Resistance↗
Technological problems of miniaturized insulin dosing devices and some approaches to clinical trials.
With the long-term goal of developing implantable insulin dosing devices, we have since 1971 developed various types of programme-controlled units for clinical research. In the initial stage, a 24-hour, fixed-programme bed-side device has been in clinical use since 1973. The good results with even labile diabetics has supplied the basis for the further development of sensorless units. Via intermediate stages, two types of miniaturized portable devices were constructed: fixed-programme and demand-programme devices. The essential equipment components have been optimized with a view to later implantability: hermetically sealed capsule for the dosing device, refilling membrane for the insulin reservoir, bubble-free drawing off of the insulin via a wick from a collapsible silicone reservoir, the stepping motor-driven roller pump of approx. 9 cm3 volume, an energy consumption of about 50 mu W, and electronic safety and alarm circuits. Because of stability problems of the insulin, the neutral insulin U-1000 used initially was changed to acid insulin U-100 (both from Hoechst).
Animals↗
[Viscosity and density fluctuations of natural respiratory gases and of mixtures of helium, oxygen and nitrogen due to temperature and composition of the gas mixture (author's transl)].
For the estimation and correction of errors in the measurement of the respiratory flow with viscosity-affected respiratory flow receptors the viscosity of natural respiratory gases (N2, O2, CO2, H2O) and of the ternary system helium-oxygen-nitrogen, which is of importance in pulmonary function diagnosis, was determined. Corresponding density values were calculated. Allowance was made for such special features of spirometry as exchange of O2 for CO2 and water vapour saturation at 37 degrees C. The viscosity of the ternary system is shown in a graph. The formulae indicated have been simplified as far as this was compatible with the demands of accuracy. The fluctuations in density and viscosity of natural respiratory gases can be read directly from a table.
Carbon Dioxide↗
Development of program-controlled portable insulin delivery devices.
Various alternatives for program-controlled insulin delivery systems, on which we have been working since 1972, are described. Fixed-programmable and demand-programmable devices, both in two parts comprising separate control and delivery units, have been miniaturized and technically improved to the extent that they can now be used for the ambulant, long-term treatment of diabetic patients. The electronic drive systems, including control and safety circuits, that are discussed using the demand-type system as an example have been conventionally designed, using CMOS technology. The mechanical components of the insulin-delivery devices, in particular the roller pump driven by a stepping motor, have been developed in such a way that they can also be employed in implantable devices, without any essential modifications. Particular attention was thus paid to the features of miniaturization, high insulin concentration, low energy consumption, and a high degree of safety and reliability. The experience obtained from broad-based clinical trials of the devices is summarized briefly.
Animals↗
Development of remotely controlled implantable devices for programmed insulin infusion.
Broadbased clinical research during recent years has shown that programme controlled insulin infusion with externally portable devices is an excellent means for improving glucose control of labile diabetics. On the basis of this experience we concentrated on the development of implantable units, which would allow the potentialities of the method to become available for long-term therapy. Implantable devices have to be small, lightweight, long-lived, biocompatible, reliable, safe and externally controllable if they are to be used in humans. We have developed such a device with a volume of 94 cm3, a weight of 180 g and a refillable insulin reservoir of 10 ml. Using an insulin concentration of 100 units per ml, the reservoir has to be refilled through the skin about every three weeks. Energy is provided for more than one year by a lithium battery. Insulin infusion is controlled by a roller pump driven by a stepping motor. Twelve different basal rates and 12 different prandial doses can be programmed by an external programmer. One hour after programming, the high prandial infusion rates return automatically to the basal rate. The telecontrol system includes circuits for acknowledgement of programme transmission, monitoring of the stepping frequency and checking of the catheter pressure. Emphasis has been placed on making the implant safe against overdosing. All the components including the insulin reservoir are encapsulated in a titanium housing. In this way, the whole insulin tract is well protected against damage, and even in the case of a leak no insulin could be released into the body because an underpressure is maintained in the interior of the titanium capsule. Overdosing due to electronic defects is prevented with additional safety circuitry, the function of which can be checked at any time, even after implantation. Research prototypes of the devices have been tested widely in dogs and have been implanted in humans recently.
Animals↗
Clinical experience in human diabetics with portable and implantable insulin minipumps.
We report our personal experience of chronic ambulatory insulin therapy via portable and implantable pumps in insulin-dependent diabetics. Fifteen patients, poorly controlled on conventional insulin injections, were equipped with portable Siemens pumps. These pumps offer compactness, safety means, portability, one-month insulin reservoir and variable insulin rates. The pump catheter was chronically inserted in the peritoneal space using a non-surgical personal technique. Our present experience, representing six patient-years of treatment (range 1 to 16 months), shows excellent steady blood glucose control (mean blood glucose is 115 +/- 5 mg/dl v. 187 +/- 21 mg/dl with conventional therapy). All incidents were minor and most were catheter related. However, there was no catheter removal or discontinuation of pump treatment. All patients declared that there was a marked improvement in their quality of life. One of the pump-treated patients agreed to be transferred to a totally implantable Siemens prototype. The pump was inserted in the muscular wall of abdomen, and the delivery catheter terminated in the peritoneal space. Refills are made percutaneously approximately every 20 days. Rates and functions of the pump are remotely controlled. Five months after implantation, results, compared with those of a portable pump, show similar excellent blood glucose control and pump precision with a further improvement in the patient's quality of life. Thus, although further miniaturization and longer autonomy are expected in the forthcoming devices, our present experience shows that, with careful patient instruction and follow up, insulin pumps could represent in the next years an alternative to conventional insulin therapy for poorly controlled diabetics.
Adolescent↗