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.

No abstract

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.

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 per‐cutaneously 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.

SUMMARYThis 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