Abstract: A device for maintaining or reestablishing a natural heart rhythm by generating an electrical stimulation signal. In particular a device in the form of an implantable heart pacemaker that displays at least one sensor arranged inside the patient's body for picking up a body-specific signal containing information concerning demand for heart performance, or another magnitude relevant to the heart. The device is characterized by the fact that connected downstream to the sensor is a processing unit that obtains from the measurement signal a body-specific rhythm signal whose periodicity is equal to or greater than the periodicity of the breathing activity, and thus lies above the periodicity of the heart activity, whereby the body-specific rhythm signal forms a control signal that influences the stimulation signal.

Abstract: Device for maintaining or restoring a natural heart rhythm through the generation of an electrical stimulation signal, in particular in the form of an implantable heart pacemaker, which device shows two sensors arranged inside the body of the patient for picking up a body-specific signal that contains information concerning the demand for heart performance or another magnitude relevant to the heart. Connected to the downstream side of the sensors is a processing unit that obtains, from the temporal difference of a body-specific signal received one after another at both sensors, a body-specific time-delay signal, which represents the length of the determined time delay. The body-specific time-delay signal forms at least indirectly a control signal that influences the point in time and/or the time sequence of the stimulation signal.

Abstract: Methods and apparatus are provided for measuring the impedance of a patient's body. Pulse generating circuitry within a rate-responsive pacemaker is used to generate an impedance measurement signal that is applied to the body of the patient with conventional pacemaker leads. The impedance measurement signal contains a series of multiphasic impedance measurement waveforms, which have no net DC value and zero value after second integration. The impedance measurement signal allows the impedance of the body to be measured without interfering with external cardiac monitoring equipment such as electrocardiogram machines.

Abstract: Methods and apparatus are provided for measuring the impedance of a patient's body. Pulse generating circuitry within a rate-responsive pacemaker is used to generate an impedance measurement signal that is applied to the body of the patient with conventional pacemaker leads. The impedance measurement signal contains a series of multiphasic impedance measurement waveforms, which have no net DC value and zero value after second integration. The impedance measurement signal allows the impedance of the body to be measured without interfering with external cardiac monitoring equipment such as electrocardiogram machines.

Abstract: A DC-to-DC converter circuit is disclosed for use in a pacemaker. The DC-to-DC converter circuit is capable of producing a pulse burst and boosting the voltage of the pulse burst up to an effective pacing amplitude, thereby eliminating the need for the multiple pump capacitors and the output capacitor. The DC-to-DC converter circuit uses a transformer to amplify the battery voltage to the required pacing amplitude. By using a transformer, DC leakage current is eliminated without the use of a decoupling capacitor, thereby achieving lower pacing thresholds. Also, each patient may be individually tested to determine their response to high frequency pulse bursts and a "customized" pacing waveshape can be produced by varying the duty cycle, polarity or pulse burst of each stimulation signal. The DC-to-DC converter circuit also reduces the polarization effect of the tissue around the electrodes.

Abstract: Cyclic total parenteral nutrition is safely administered by tapering the infusion rate over a substantial period of time at the beginning and end of the infusion cycle. An infusion pump is disclosed which automatically calculates and performs a cycle profile having an appropriate steady-state rate and appropriate tapers in accordance with pre-established criteria when total volume and total infusion time per cycle are entered. The pump has a sleep mode for energy conservation without loss of memory when predetermined periods of inactivity occur.

Abstract: A plurality of infusion pump modules are detachably connected to a portable central management unit. The modules can be programmed by the central management unit, and their operating information displayed by the central management unit, when they are connected to it; yet the modules, once programmed, can operate independently when detached from the central mangagement unit, and they can display limited operational information on their own.

Abstract: A safety system for battery-operated, microprocessor-controlled infusion pumps using separate primary and reserve batteries. When the primary battery nears exhaustion, the reserve battery is switched in and an interval timer is started, but the pump operation is not interfered with. At the expiration of the timer interval, the pump is switched to a KVO mode to keep it in minimal operation as long as possible. When the reserve battery also nears exhaustion, the microprocessor is signalled to perform an orderly shutdown routine while battery power is still available. Audible alarms may be provided to apprise nursing personnel of the various phases in the system's operation.

Abstract: The present invention is a sensing amplifier circuit for a tissue stimulator (72) for supplying or attenuating far field signal voltage artifacts comprising a full differential amplifier having a first (94, 136) and second (96, 142) stage amplifiers for respectively receiving a second and first signal voltage output from a sensing mean (80, 82), and a switch means for controlling an input of the second signal voltage output from said sensing means to the first stage amplifier (94, 136).