Method and apparatus for self-test of defibrillation and pacing circuits including a patient isolation switch

A method for testing a pacing switch in a defibrillator, the defibrillator having an energy storage capacitor and an output circuit with a plurality of switches for coupling the energy storage capacitor to a patient, the defibrillator also having an output for applying defibrillation pulses to the patient, the method comprising:

• providing control signals for making one or more of the switches of the output circuit conducting while the control signal for the pacing switch is not set to the conducting state;
• measuring a selected energy parameter that is indicative of the voltage across the output of the defibrillator;
• and
• if the energy parameter changes by more than a predetermined threshold amount, providing an error indication.

A method for testing a pacing switch in a defibrillator, the defibrillator having an energy storage capacitor and an output circuit with a plurality of switches for coupling the energy storage capacitor to a patient, the defibrillator also having an output for applying defibrillation pulses to the patient, the method comprising:

• providing control signals for making one or more of the switches of the output circuit conducting while the control signal for the pacing switch is set to the conducting state;
• measuring an energy parameter that is indicative of the voltage across the output of the defibrillator;
• and
• if the energy parameter does not change by more than a predetermined threshold amount, providing an error indication.

A method for verifying the integrity of an isolation switch in a defibrillator, the defibrillator having an energy storage capacitor and an output circuit with a plurality of switches for coupling the energy storage capacitor to the isolation switch, and also having an impedance drive circuit with a preamplifier and an impedance drive current, the method comprising:

• providing control signals for making one or more of the switches of the output circuit conducting while the control signal for the isolation switch is not set to the conducting state;
• measuring a selected energy parameter that is affected by changes in the impedance drive current;
• and
• if the selected energy parameter changes by more than a predetermined threshold amount, providing an error indication.

A method for verifying the integrity of the switches in an H-bridge output circuit of a defibrillator while the output of the defibrillator is in an open circuit state, the method comprising:

• providing a control signal to place an isolation relay in a conducting state;
• providing control signals to make the switches in the H-bridge output circuit conducting such that each leg of the H-bridge output circuit is made to be conducting in sequence;
• monitoring the preamplifier output;
• and
• if a predetermined change in the preamplifier output is detected, providing an error signal indicating that a switch is stuck in a conducting state.

A method for verifying the integrity of the switches in an H-bridge output circuit of a defibrillator while the defibrillator output is in an open circuit state, the method comprising:

• providing control signals to place an isolation relay in a conducting state;
• providing control signals to make the NW and SE legs of the H-bridge output circuit conducting and monitoring the preamplifier output;
• and
• if the preamplifier output remains relatively constant, providing an error signal indicating that switches in one or both of the NW or SE legs of the H-bridge output circuit are stuck in a nonconducting state.