Abstract: A battery pack (10) is disclosed for use with a medical instrument (12). The battery pack includes a housing (14), defined by a case (16) and cover (18). The housing includes a storage section (22), for receiving batteries (78 and 80), and a connector section (24) on one side of the storage section for cooperating with a latch assembly (110), ejection spring (142), and electrical connectors (108) provided adjacent a battery tray (98) on the instrument. Specifically, the connector section includes an aligned latch surface (64), ejection surface (62), and electrical connectors (86) that cooperatively engage the latch assembly, ejection spring, and connectors on the instrument. As a result, the battery pack can be quickly, easily, and effectively attached to the instrument, in spite of the side-mounted nature of the connector section.

Abstract: An energy transfer circuit (40) for delivering a cardiac defibrillation pulse to a patient (50). An energy storage capacitor (16) is coupled to a pair of electrodes (52a, 52b) through an electronic switch (42). The electronic switch is controlled by a control circuit (20). A current shunt 56 is connected in parallel with a pair of defibrillation electrodes (52a, 52b) to divert a leakage current that flows through the electronic switch away from the patient when a defibrillation pulse is not being delivered. A current sensor (64) or a voltage sensor (72) provide a feedback signal to the control circuit to regulate the energy of the defibrillation pulse that flows through the patient.

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: An internal defibrillation electrode (10) is disclosed including a disposable electrode (12) and a reusable handle (14). The electrode includes an electrode spoon (16), a shaft (18), and a barrier sleeve (20). The handle includes a handle body (58), electrical cable (60), sleeve connector (62), and electrical connector (64). The handle has a dagger-style configuration that makes the electrode assembly easy to use and is further constructed to allow the electrode to be quickly and reliably attached. In that regard, during assembly, a bayonet (32) on the shaft of the electrode is engaged in a bayonet receptacle (68) of the handle. The sleeve is then pulled over the handle to form a barrier between the handle and the environment. After the electrode assembly is used, the sleeve is removed from the handle, the electrode disengaged from the handle, and the electrode disposed of. After attaching a new electrode, the handle is then ready for immediate service.

Abstract: Disclosed is an electrode strip (10) for use in electrocardiography comprising a flexible and substantially inextendible substrate (14), a plurality of conductive leads (16) and an insulating cover layer (17) including a plurality of apertures (24) therethrough. The conductive leads extend from a connector (22) to different ones of the apertures to form electrode sites (26). A plurality of regions of extensibility (30) in the strip allow selective positioning of the apertures on a body.

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: A defibrillation training system (10) is disclosed for use in training individuals in the proper positioning of defibrillation electrodes on a patient. The system includes a pair of training electrodes (12), each of which includes a permanent magnet (40). The training electrodes are attached to a manikin (14) at two electrode placement sites (42 and 44) provided with arrays (46 and 48) of Hall-effect sensors. The magnetic field produced by the permanent magnet in each electrode is sensed by the corresponding array, allowing an electrode placement monitor (16), attached to the manikin, to determine the electrodes' positions. The placement monitor then determines whether any adjustments in the electrodes' positions are required and prompts the individual being trained accordingly.

Abstract: A connector (10) is disclosed for providing a connection, for example, a battery pack (16) and a medical instrument (14). The connector includes a grommet (18), which flexibly secures an internal conductive post (24) and external conductive post (26) to the instrument. Drop-shaped external and internal sections 28 and 32 of grommet 18 cooperatively engage external and internal flanges 54 and 58 on the instrument to restrict rotation of the connector, while a central section 30 of the grommet has a circular cross section to provide a seal between the connector and the instrument in the event the connector does rotate. The external section of the grommet is compressed slightly by the battery pack upon insertion into the instrument. A connector constructed with these features can be easily removed from the instrument for servicing and seals the interior of the instrument as well as connections made to the external post.

Abstract: A method and apparatus for use with medical electrode systems that sense the integrity of lead connections and patient transthoracic impedance is provided. In an ECG electrode application, a carrier circuit (12) produces two carrier signals (S.sub.C1 and S.sub.C2) that are out of phase with each other. The S.sub.C1 signal is applied to an RA lead through a terminating impedance (Z1). The S.sub.C2 signal is applied to LA, LL and V leads through terminating impedances (Z2, Z3, and Z4). Each of the S.sub.C1 and S.sub.C2 carrier signals comprises a lead impedance frequency component (S.sub.LI) and an impedance respiration frequency component (S.sub.IR). First stage amplifiers (A1, A2, and A3) located in an ECG preamplifier (13) amplify the difference between a lead voltage on the RA lead (V.sub.RA) and lead voltages on the LA, LL, and V leads (V.sub.LA, V.sub.LL and V.sub.V). High pass filters (F1, F2 and F3) remove patient ECG signals from the outputs of A1, A2 and A3 to produce first stage output voltages (V.

Abstract: A differential lead impedance comparison apparatus (10) senses lead impedance and compensates for patient-to-patient and electrode variability. A bridge circuit (12) is connected to one end of electrode conductors (22, 24 and 26) in an ECG Leads I configuration. The other end of the conductors (22, 24 and 26) are connected to a patient (18) via electrodes (RA, LA and LL). Leads formed in part by RA, LA and LL and the respective conductors (22, 24 and 26) have lead impedances (R.sub.b, R.sub.a, and R.sub.c). Constant current sources (11, 12 and 13) are connected to the conductors (22, 24 and 26) and supply constant AC currents (I.sub.1, I.sub.2 and I.sub.3). A first bridge output voltage (V.sub.M) is produced by I.sub.1 and a combination 32 of R.sub.a, R.sub.b, and R.sub.c. A second bridge output voltage (V.sub.P) is produced by I.sub.2 and a combination 34 of R.sub.a, R.sub.b, and R.sub.c. A differential amplifier circuit (14) differentially amplifies the V.sub.M and V.sub.

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.

Abstract: A flexible, disposable stimulation electrode (10) having low current densities and a long shelf life is disclosed. The electrode (10) includes a nonconducting backing layer (12). A tinfoil plate (16) is displaced inwardly from the edge of the backing layer (12), in contact with a skin-facing surface of the backing layer (12). A conductive gel (18) covers the exposed surface of the plate of the plate (16) and a portion of the skin-facing surface of the backing layer (12) that surrounds the plate (16). The gel (18) is formed by a mixture comprising: an ultraviolet radiation (UV) curable resin; a magnesium bromide electrolyte; and, a thioglycerol chain transfer agent. The resin is a urethane-acrylic oligomer made UV curable by the addition of a water-miscible photoinitiator. The gel (18) has an annular tapered edge (52) extending outwardly from the plate (16).

Abstract: A method and apparatus for use with medical electrode systems that sense the integrity of lead connections and patient transthoracic impedance is provided. In an ECG electrode application, a carrier circuit (12) produces two carrier signals (S.sub.C1 and S.sub.C2) that are out of phase with each other. The S.sub.C1 signal is applied to an RA lead through a terminating impedance (Z1). The S.sub.C2 signal is applied to LA, LL and V leads through terminating impedances (Z2, Z3, and Z4). Each of the S.sub.C1 and S.sub.C2 carrier signals comprises a lead impedance frequency component (S.sub.LI) and an impedance respiration frequency component (S.sub.IR). First stage amplifiers (A1, A2, and A3) located in an ECG preamplifier (13) amplify the difference between a lead voltage on the RA lead (V.sub.RA) and lead voltages on the LA, LL, and V leads (V.sub.LA, V.sub.LL and V.sub.V). High pass filters (F1, F2 and F3) remove patient ECG signals from the outputs of A1, A2 and A3 to produce first stage output voltages (V.

Abstract: A differential lead impedance comparison apparatus (10) senses lead impedance and compensates for patient-to-patient and electrode variability. A bridge circuit (12) is connected to one end of electrode conductors (22, 24 and 26) in an ECG Leads I configuration. The other end of the conductors (22, 24 and 26) are connected to a patient (18) via electrodes (RA, LA and LL). Leads formed in part by RA, LA and LL and the respective conductors (22, 24 and 26) have lead impedances (R.sub.b, R.sub.a, and R.sub.c). Constant current sources (I1, I2 and I3) are connected to the conductors (22, 24, and 26) and supply constant AC currents (I.sub.1, I.sub.2 and I.sub.3). A first bridge output voltage (V.sub.M) is produced by I.sub.1 and a combination 32 of R.sub.a, R.sub.b, and R.sub.c. A second bridge output voltage (V.sub.P) is produced by I.sub.2 and a combination 34 of R.sub.a, R.sub.b, and R.sub.c. A differential amplifier circuit (14) differentially amplifies the V.sub.M and V.sub.

Abstract: Disclosed is an adaptor (28, 90) for use with a paddle electrode equipped defibrillator (10) that allows alternative use of disposable defibrillation electrodes. In some applications, the adaptor (28, 90) is positioned and retained in the paddle electrode stowage region (18) of the defibrillator (10) with the paddle electrodes (14, 16) being retained in an accessible position by the adaptor. Electrical contacts (75) and a cable (34) that are included in the adaptor electrically connect the paddle electrodes (14, 16) with connectors for disposable defibrillation electrodes, which are mounted at the distal end of the adaptor cable (34). When disposable defibrillation electrodes (36, 38) are placed in the adaptor cable connectors and positioned on the body of a patient, a defibrillation sequence is carried out utilizing the same controls and sequence that are used to defibrillate with the paddle electrodes.

Abstract: A discriminating connector (38) can be connected to a defibrillation electrode (36), but not to an ECG monitoring electrode (10), even though both electrodes (38 and 10) have identical conducting posts (50 and 12). The discriminating connector (38) is formed by upper and lower members (40 and 42) and a pivot (44) that connects the upper and lower members (40 and 42) so as to define an opening (43). A mating receptacle (48) is disposed within an upper wall (74) of the opening (43). A distance (49) between the mating receptacle (48) and the pivot (44) is equal to or greater than a distance (59) between the conducting post (50) and an outer edge (53) of the defibrillation electrode (36) so as to permit the conducting post (50) to be received by the mating receptacle (48). A conductive receptacle (15) in a prior art ECG connector (11) is identical to the mating receptacle (48) and can be attached to the conducting post (50) on the defibrillation electrode (36).

Abstract: Under the present invention, a method and apparatus are provided for compensating for the effect temperature variations have on the wavelength of light emitted by the oximeter sensor light sources (40, 42). In pulse oximetry, LEDs are typically employed to expose tissue to light at two different wavelengths. The light illuminating the tissue is received by a detector (38) where signals proportional to the intensity of light are produced. These signals are then processed by the oximeter circuitry to produce an indication of oxygen saturation. Because current oximetry techniques are dependent upon the wavelengths of light emitted by the LEDs (40-42), the wavelengths must be known. Even when predetermined combinations of LEDs (40-42) having relatively precise wavelengths are employed, variations in the wavelength of light emitted may result. Because the sensor (12) may be exposed to a significant range of temperatures while in use, the effect of temperature on the wavelengths may be significant.