Abstract: An external defibrillator with a microprocessor for testing the integrity of an output circuit prior to and during the delivery of a multiphasic defibrillation pulse from an energy storage capacitor coupled to the output circuit is disclosed. The output circuit contains a plurality of switches. The integrity of the output circuit and the output switches is determined by selectively monitoring the changes in the voltage level on the energy storage capacitor while certain tests or functions are being performed. A scaling circuit steps down the voltage level of the high-energy storage device so that it can be measured and monitored by the microprocessor. The microprocessor may compensate for the failure of an output switch by locating a usable set of output switches and using them to provide a discharge path through the output circuit for application of a monophasic pulse.

Abstract: A high energy transfer relay includes a housing, a solenoid, a pivot arm, a stationary contact, a switching contact and a leaf spring. The switching contact is mounted on the leaf spring. The armature of the solenoid is coupled to the pivot arm such that when the solenoid is energized, the pivot arm moves in the direction of the stationary contact. Movement is against the force of the leaf spring which is positioned to bias the pivot arm away from the stationary contact against a stop. The leaf spring also pre-loads the pivot point. In addition, the resilience of the leaf spring cushions the impact of the switching contact on the stationary contact to help prevent contact bounce. The outer end of the pivot arm includes a flat that coacts with a flat wall to form an air cushion. The air cushion also assists in preventing contact bounce by absorbing the momentum of the pivot arm after the contacts mate.

Abstract: A battery pack (28) for a portable defibrillator (30). The battery pack has a latch (34) that is biased in an extended position. When the battery pack is inserted into a battery well (30) in the portable defibrillator, the latch automatically latches into a slot (124) to secure the battery pack in tile battery well. Ridges (112) are provided on the floor (108) of the battery well to reduce the friction between the battery pack and the floor of the well as the battery pack is inserted into the defibrillator. A ridge (38) is also provided around the periphery of the top (36) of the battery pack to reduce the friction between the battery pack and the ceiling of the battery well. A right wall (44) of the battery pack is inclined from vertical so that a cross section of the battery pack is trapezoid in shape. The asymmetric cross-section prevents the battery pack from being incorrectly inserted into the battery well.

Abstract: An external defibrillator (8) with an output circuit (14) having four legs arrayed in the form of an "H" (an "H-bridge") is disclosed. Each leg of the output circuit contains a solid-state switch (31, 32, 33, 34). By selectively switching on pairs of switches in the H-bridge, a biphasic defibrillation pulse may be applied to a patient. The switches in three of the legs of the H-bridge output circuit are preferably silicon controlled rectifiers (SCRs). Gate drive circuits (51, 53, 54) are coupled to the SCRs to bias the SCRs with a voltage that allows the SCRs to remain turned-on even when conducting low current. The switch in the fourth leg is preferably a pair of insulated gate bipolar transistors (IGBTs) coupled in series. A gate drive circuit (52) is coupled to the gate of the IGBTs to provide a slow turn-on and a fast turn-off of the IGBTs.

Abstract: The serial data port of a terminal device is normally connected to a peripheral device for data transfer. A telephone connection with a public switched telephone network (PSTN) is monitored to detect, however, if there is an incoming priority data message. If so, the terminal device is notified of the priority message and is allowed to terminate its current data transfer with the peripheral device. The terminal device is then connected to the PSTN to receive the priority message. At the conclusion of the priority message, the terminal device is reconnected to the peripheral device to complete the interrupted data transfer. In this way, the serial port of the terminal device can be used for data transfer with different peripherals, without jeopardizing or delaying reception of a priority data message.

Abstract: In an external cardiac defibrillator (8), a method and system for determining when a relay (22) has failed in a conductive state. The defibrillator (8) includes a charge circuit (14) that charges an energy storage capacitor (C) to a predetermined voltage. The relay (22) is closed to direct a defibrillation pulse from the energy storage capacitor to a patient (25) needing ventricular therapy. The relay (22) is then opened following application of the defibrillation pulse. A monitor circuit (18) monitors the voltage on the energy storage capacitor. If the measured voltage across the energy storage capacitor (C) is less than or equal to a threshold value after a predetermined delay, the relay (22) has failed. If the measured voltage exceeds the threshold value, the relay (22) is operating correctly.

Abstract: A battery pack (28) for a portable defibrillator (30). The battery pack has a latch (34) that is biased in an extended position. When the battery pack is inserted into a battery well (30) in the portable defibrillator, the latch automatically latches into a slot (124) to secure the battery pack in the battery well. Ridges (112) are provided on the floor (108) of the battery well to reduce the friction between the battery pack and the floor of the well as the battery pack is inserted into the defibrillator. A ridge (38) is also provided around the periphery of the top (36) of the battery pack to reduce the friction between the battery pack and the ceiling of the battery well. A right wall (44) of the battery pack is inclined from vertical so that a cross section of the battery pack is trapezoid in shape. The asymmetric cross-section prevents the battery pack from being incorrectly inserted into the battery well.

Abstract: A portable defibrillator (10) with a common therapy/data port (12). A set of electrodes (34) is connected to the therapy/data port to connect the defibrillator to a patient. If connected to a patient, the defibrillator operates in a normal mode of operation where it analyzes a patient's electrocardiogram (ECG), and, if required, applies defibrillation therapy through the port to the patient. A communication cable (42) is connected to the therapy/data port to connect the defibrillator to an auxiliary component (44). If connected to an auxiliary component, the defibrillator operates in a data communication mode of operation where data may be transmitted to and received from the auxiliary component through the therapy/data port. A test cable is connected to the therapy/data port to connect the defibrillator to a test load. If connected to a test load, the defibrillator operates in a user test mode of operation to allow a user to test the operation of the defibrillator.

Abstract: An adapter for connecting combination electrodes to a defibrillator/monitor/pacer. The adapter isolates the pacer from the defibrillator when a defibrillation pulse is applied over the combination electrodes. In a first embodiment of the adapter, the pacer is conductively connected to the combination electrodes only when the pacer's power supply is turned on. In a second embodiment of the adapter, the pacer is normally connected to the combination electrodes, but is disconnected when the defibrillator/monitor/pacer is analyzing a patient's ECG or when the defibrillator is charging to enable it to deliver a defibrillation pulse. Also provided in the adapter is a contact assembly for connecting the adapter to defibrillation paddles from the defibrillator.

Abstract: An environmentally insensitive device is described. The device uses a passive paper guide to direct an output paper stream from a paper source contained within the unit to an output aperture. The passive paper guide uses two opposing surfaces to define a radius of curvature through which the paper strip is guided. Use of longitudinal ridges along one or both of the surfaces reduces friction along the guide. By providing a rotatable output cover over the aperture and using a unit cover, a printed output can be achieved while maintaining the shielding of the unit from environmental effects.

Abstract: A battery selecting and charging system forms part of a portable electronic device, preferably a portable medical device. When the device is powered up, a selecting circuit selects one of two rechargeable batteries to power the device until it is depleted, and then automatically switches to the other battery. When the second battery is depleted, both batteries are selected to power the device. When the device is powered down, a battery charging circuit, having both a high and low charge section, provides a high charge to the battery having the greatest terminal voltage. Thereafter, the high charge is applied to the other battery, the low charge is applied to the first battery, and then the low charge is applied to the second battery. The battery charging circuit monitors the terminal voltage to prevent any damage to the batteries or the device.

Abstract: A first electrical connector of an interface is provided on a floating plug assembly mounted on one component of a physiological instrument. A second electrical connector of the interface is mounted in a socket assembly constructed in another component that can be coupled to the first component by relative linear translation. Guides located in the socket assembly capture fingers on the plug assembly as the plug assembly is inserted in the socket assembly. The guides orient the plug assembly so that the first connector is correctly aligned with the second connector. The connectors are automatically joined as the first component is coupled to the second component.

Abstract: A bifurcated electrical connector (14) includes a precordial lead connection site (18) and a limb lead connection site (16). A precordial connector (26) can be fitted into the precordial lead connection site (18) and a limb lead connector (32) can be fitted into the limb lead assembly connection site (16). The force required to separate the limb lead connector from the limb lead connection site is greater than the force required to separate the precordial lead connector from the precordial lead connection site. Additionally, a cover flap (75) covers the precordial lead connection site when the precordial electrodes are not in use.

Abstract: A portable electronic unit, such as a defibrillator, includes an autotest system for automatically self-testing various electrical components within the unit during quiescent periods. The autotest system includes an autotest routine that performs an extensive array of rigorous yet time-consuming tests that are impractical to perform during normal modes of operation of the unit. A real-time clock can be set to initiate the autotest routine at a time when the unit is unlikely to be used for its normal mode of operation. The autotest system provides a strip chart printout of the results of the various self-tests performed on the unit, and provides messages on a visual display of any error conditions. If the autotest system detects a needs service malfunction, the operator must acknowledge the error with an input to the unit before the unit will enter into its normal mode of operation.

Abstract: A portable electronic device having a stationary housing enclosing a first electric circuit and a pivotable housing enclosing a second electric circuit, uses a mechanical and electrical interconnection assembly for interconnecting the two housings and circuits. The mechanical assembly includes a pivot and friction assembly that pivotally couples the stationary and pivotal housings together, and allows the pivotable housing to be held at a variety of angular orientations with respect to the stationary housing. The electrical assembly includes an electrical connector of a flexible web type that pivotally and electrically connects the first and second electric circuits together. Rather than pivoting at the pivot point or axis, the electrical connector pivots about or along a relatively great distance compared to the pivot axis, thereby greatly reducing the possibility of the electrical conductor breaking at the pivot.

Abstract: A communication interface for transmitting serial data between a first and a second interconnectable medical instrument. A set of vertically aligned, horizontally extending leaf springs are disposed on opposing surfaces of the first and second medical instruments. A pair of serial data transfer circuits within the first and second medical instruments transmit and receive serial data through a pair of the leaf springs.

Abstract: A medical electronic device having an electronic circuit allows for additional functional modules having electrical components to electrically couple to the medical electronic circuit. The modular system includes a housing enclosing the medical electronic circuit and a module enclosing the electrical components containing the additional functionality. A socket for releasably receiving the module is formed in a top side of the housing and is defined by a bottom wall and a side wall of the housing. The side wall has a rib projecting therefrom and extending from the bottom wall toward the top of the housing. The bottom wall has first and second holes formed therein proximate to the first rib. The module includes front and rear sides each having a channel formed therein for receiving the rib. A pair of guide pins extend below the bottom of the case, on opposing sides of an electrical connector.

Abstract: A method and system for automatic or semi-automatic defibrillation using redundant processing is provided. In a preferred embodiment, two microprocessors each separately analyze electrocardiogram signals from a patient in order to separately determine whether the patient should be treated. If both microprocessors determine that the patient should be treated, a treatment subsystem defibrillates the patient by delivering a defibrillation charge to the patient. In a semi-automatic embodiment, the treatment subsystem only delivers a defibrillation charge to the patient if a human operator has responded to a visual indication that the patient should be treated by manually activating the defibrillator.

Abstract: A mechanical connector (10) for securing together an electrocardiogram monitor (12) and a defibrillator (14). The connector includes a tongue (16) disposed on a side surface (18) of the ECG monitor and a set of angle flanges (22) disposed on the defibrillator. A keyway (52) extends lengthwise at a rearward portion of a channel (36) between the tongue (16) and the side surface (18). A key (50) fits within the keyway (52) when the tongue (16) is slid within the set of angle flanges (22). The key (50) prevents the defibrillator from being fully coupled with an ECG monitor that lacks the corresponding keyway.