Abstract: A defibrillator (10) is disclosed in which measured information concerning the energy delivered by the defibrillator to a meter (56) is employed to calibrate subsequent discharges by the defibrillator at the same energy level. In connection with that process, a microprocessor (70) controls the operation of a feedback loop (50), including a controlled-gain amplifier (64), level detector (66), adder (68) and energy charger (58), to adjust the voltage applied to a discharge capacitor (54) in response to the energy measured by the meter. The information can be input to the microprocessor either manually or automatically and can be used by the microprocessor in performing a piecewise linear approximation of the voltage adjustment required to deliver the desired nominal energy, or in performing a direct computation of that adjustment. This process is repeated for each of the energy levels selectively dischargeable by the defibrillator.

Abstract: A pacemaker/monitor (10) is disclosed for applying a pacing current to a patient through a pair of pacing electrodes (12). The pacemaker/monitor includes a plurality of manual inputs (26) for use by an operator and a microprocessor (16) that responds to programmed instructions stored in read-only memory (20). Cooperatively, these components control the operation of the pacemaker/monitor. In that regard, the desired magnitude of the pacing current in input to the pacemaker/monitor via a limitless rotary current control (46), formed by a rotary pulse generator (52) and a decoder circuit (50). The microprocessor monitors the operation of the various manual inputs and sets the pacing current to zero milliamperes in the event one of the inputs is used, regardless of the position of the rotary pulse generator. For example, when the pacemaker/monitor is turned ON, or the pacing mode of operation is selected, the pacing current is zeroed.

Abstract: An apparatus (10) for transmitting a patient physiological signal is provided. A converter (12) includes a front end circuit (28) that receives and conditions a patient physiological signal, V.sub.P, and produces conditioned signal, V.sub.C. A magnitude of V.sub.C is proportional to an amplitude of V.sub.P offset by a negative DC voltage. A track and ramp circuit (30) receives V.sub.C and produces a tracking voltage, V.sub.T. A magnitude of V.sub.T is inversely proportional to the magnitude of V.sub.C when the track and ramp circuit is in a tracking mode. A controller (16) includes a clock that produces clock pulses, V.sub.CK and a divider (38) that divides the clock pulse frequency and produces a trigger pulse, V.sub.TRIG. A leading edge of the V.sub.TRIG pulse starts a counter (40) counting V.sub.CK pulses. The leading edge of an optically transmitted V.sub.TRIG pulse is applied to the latch circuit (32), which produces a ramp command voltage, V.sub.R. A high V.sub.