Defibrillator - Cardiology - Lecture Slides, Slides of Cardiology

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Defibrillator

Definition

An electrical device used to counteract fibrillation of the heart muscle and restore normal heartbeat by applying a brief electric shock

For every minute that passes between collapse and defibrillation, survival rates from witnessed VF SCA decrease 7% to 10% if no CPR is provided

Ann Emerg Med. 1993;22:1652– 1658

3 actions that must occur

within the 1st^ moment of SCA

• Activation of the emergency medical services (EMS) system
• Provision of CPR, and
• Operation of an AED

When 2 or more rescuers are present, activation of EMS and initiation of CPR can occur simultaneously

Shock First Vs CPR First

• Out-of-hospital witnessed arrest
• If AED is immediately available
• Use the AED as soon as possible.

In hospital

CPR first

Shock First Vs CPR First contd..

• One cycle of CPR consists of 30 compressions and 2 breaths
• When compressions are delivered at a rate of about 100 per minute, 5 cycles of CPR should take roughly 2 minutes

This recommendation regarding CPR prior to attempted defibrillation is supported by 2 clinical studies

JAMA. 2003;289:1389 – 1395 JAMA. 1999;281:1182– 1188

Defibrillation waveforms

and energy levels

• The energy settings are designed to provide the lowest effective energy needed to terminate VF
• Shock success -Termination of VF for at least 5 sec following the shock
• VF frequently recurs after successful shocks, but this recurrence should not be equated with shock failure

• Modern defibrillators are classified as Monophasic Biphasic
• Energy levels vary by type of device
• No specific waveform is associated with a higher rate of return of spontaneous circulation (ROSC) or rates of survival to hospital discharge after cardiac arrest

Biphasic waveform

Defibrillators

• The optimal energy for termination rate for VF has not been determined
• 200 J is safe and has equivalent or higher efficacy for termination of VF than monophasic waveform shocks of equivalent or higher energy (Class IIa)

Automated external

Defibrillators

• AEDs are sophisticated, reliable devices
• Use voice and visual prompts to guide lay rescuers and healthcare providers to safely defibrillate VF SCA

Electrode placement

• Right pad – Right Infraclavicular
• Left pad – Inf-lateral left chest, lateral to the left breast
• Position the pad at least 1 inch (2.5 cm) away from the implantable medical device

• Do not place pads directly on top of a transdermal medication patch
• If the victim’s chest is covered with water or the victim is extremely diaphoretic, wipe the chest before attaching pads
• AEDs can be used when the victim is lying on snow or ice
• If the victim has a hairy chest, remove some hair