US 6,208,895 B1 · Circuit for performing external pacing and biphasic defibrillation

Abstract

An external defibrillator/pacer (8) includes an output circuit (14) with four legs arrayed to form an H-bridge coupled to an energy storage capacitor. The energy storage capacitor delivers an external defibrillation pulse with stored energy during a defibrillation mode and an external pacing pulse during a pacing mode. Each leg of the output circuit contains a switch (SW1-SW4). In a defibrillation mode, pairs of switches in the H-bridge are selectively switched to generate a biphasic defibrillation pulse. Three switches (SW1, SW3, SW4) are 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 in response to control signals. One switch (SW2) includes an insulated gate bipolar transistor (IGBT). 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 IGBT. In a pacing mode, a bypass circuit or current source circuit is used to provide a current path bypassing an SCR switch (SW3), which cannot be triggered by the relatively low current of pacing pulses. One of the SCRs (SW4) may be replaced with an IGBT to allow generation of the pacing pulse with opposite polarity of the first phase of the defibrillation pulse.

Claims33

Dependent claims

A circuit that generates a defibrillation pulse in a defibrillation mode and a pacing pulse in a pacing mode, the circuit comprising:

an energy storage capacitor having a first electrode and a second electrode;
a charging circuit coupled to the energy storage capacitor, wherein the charging circuit is configured to charge the energy storage capacitor;
an energy transfer circuit coupled to the energy storage capacitor, the energy transfer circuit having a first output lead and a second output lead, wherein the energy transfer circuit is configured to selectively electrically couple the first and second electrodes of the energy storage capacitor to the first and second output leads;
and
a control circuit coupled to the charging circuit and the energy transfer circuit, wherein the control circuit is configured to cause the charging circuit to charge the energy storage capacitor to a predetermined level and, when the energy storage capacitor is charged, to control the energy transfer circuit to couple the first and second electrodes of the energy storage capacitor to the first and second output leads of the energy transfer circuit so that the energy transfer circuit provides:
during the defibrillation mode, an external defibrillation pulse at the first and second output leads using energy stored in the energy storage capacitor, and
during the pacing mode, an external pacing pulse at the first and second output leads using energy stored in the energy storage capacitor.

4 more elements

Dependencies are inferred from the claim text.

Circuit for performing external pacing and biphasic defibrillation

Life of this patent

Circuit for performing external pacing and biphasic defibrillation

Life of this patent

Abstract

Claims33