Defibrillation consists of delivering a therapeutic dose of electrical energy to the affected heart with a device called a defibrillator. This device delivers pulses in two different waves: Monophasic and Biphasic

Problem Solving[]

100 Block diagram of defibrillator

Amplifier Circuit[]

The ECG amplifier (A1) circuit is a comparator circuit. It compares the pot resistor (R3 wiper) to the voltage divider network (R3/R4). The wiper resistor is a mechanical device and like most mechanical devices it is the first component to become defective. If R3 has a malfunction then the defibrillator won’t charge to the selected setting (e.g. 360 joules).


The charge capacitor stores energy in the electric field between the capacitor plates. The capacitor stores after the energy for discharge when the switches change state after the discharge buttons both have been pressed at the same time.

Doesn't discharge[]

These common problems are usually what cause the defibrillator not to discharge.

  • 1. Device is set in "sync' mode
  • 2. Only one discharge button is depressed.

Performance Checks[]

  • Batteries
  • Output
  • Pacing
  • Paddles for pits
  • ECG Leads
  • Chassis for cracks
  • Power and Paddle Cords (e.g. ensure no fissures, cuts, or broken wires)
  • Date and Time
  • Paper installed correctly
  • Outdated supplies (e.g. gel pad electrodes)
  • Knobs
  • etc.