Abstract: Circuits for controlling the current flow of an energy pulse as a function of the temperature of a resistive element in the circuit so that the current flow varies over time in accordance with a predetermined waveform. The circuits include at least one negative temperature coefficient thermistor connected between an energy storage device and connectors for delivering energy stored in the storage source to an external load. In one embodiment of the invention the circuit includes a second thermistor for shunting a residual portion of the current delivered by an energy pulse away from the external load. In another embodiment of the circuit, a small inductive device is used for adjusting the shape of the predetermined waveform. In yet another embodiment of the device, a plurality of thermistors arranged in a bridge-like configuration are used to control the current of the energy pulse so that its waveform is biphasic.

Abstract: Circuits for controlling the current flow of an energy pulse as a function of the temperature of a resistive element in the circuit so that the current flow varies over time in accordance with a predetermined waveform. The circuits include at least one negative temperature coefficient thermistor connected between an energy storage device and connectors for delivering energy stored in the storage source to an external load. In one embodiment of the invention the circuit includes a second thermistor for shunting a residual portion of the current delivered by an energy pulse away from the external load. In another embodiment of the circuit, a small inductive device is used for adjusting the shape of the predetermined waveform. In yet another embodiment of the device, a plurality of thermistors arranged in a bridge-like configuration are used to control the current of the energy pulse so that its waveform is biphasic.

Abstract: Disclosed is a cardiac defibrillator for providing a cardiac defibrillation pulse to a patient. The defibrillator comprises a switch contact (14) mounted on a movable switch (10) that moves between a charge position and a discharge position. In the charge position, the switch contact is coupled to a high-voltage battery (22) in order to provide a charge to an energy storage capacitor (30). When the movable switch is released from the charge position, the switch contact engages an electrode contact (32) and a defibrillation pulse flows into a patient (40). The duration of the cardiac defibrillation pulse can be varied by changing the length of time that the switch contact remains engaged with electrode contact. Also disposed within the switch contact path is a discharge contact (42), which is connected to a discharge resistor (48).

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 portable, interactive medical electronic device exemplified by a defibrillator. The device obtains information about a patient's condition, such as ECG and transthoracic impedance data, directly from the patient, and information pertinent to the treatment of the patient indirectly through an operator of the device, and produces a medically appropriate action such as a defibrillation shock in response. Indirect information is obtained through information processing means that includes means for prompting the operator of the device and means for receiving the operator's responses thereto. Prompts may include both questions and instructions, and in one embodiment the information processing means obtains the assent of the operator before causing the defibrillation shock. Indirect information may include information as to whether the patient is conscious, and as to whether or not cardiopulmonary resuscitation has been performed.

Abstract: A portable, interactive medical electronic device exemplified by a defibrillator. The device obtains information about a patient's condition, such as ECG and transthoracic impedance data, directly from the patient, and information pertinent to the treatment of the patient indirectly through an operator of the device, and produces a medically appropriate action such as a defibrillation shock in response. Indirect information is obtained through information processing means that includes means for prompting the operator of the device and means for receiving the operator's responses thereto. Prompts may include both questions and instructions, and in one embodiment the information processing means obtains the assent of the operator before causing the defibrillation shock. Indirect information may include information as to whether the patient is conscious, and as to whether or not cardiopulmonary resuscitiation has been performed.