Defibrillator

Defibrillator

Electronic defibrillation is the single most important therapy for the treatment of patients in cardiac arrest.  Most victims of sudden cardiac death initially suffer from ventricular fibrillation, which can lead to a complete absence of electrical and mechanical heart activity within 15 minutes.  Cardiopulmonary resuscitation (CPR) may keep blood and oxygen circulating through the body, but only defibrillation can reestablish normal contraction rhythms.

As the name suggests, defibrillation stops fibrillation, the useless trembling that a person’s heart muscles can adopt during a cardiac arrest.  Simply speaking, a defibrillator works by using a moderately high voltage (something like 200–1000 volts) to pass an electric current through the heart so it’s shocked into working normally again.  The patient’s heart can receive up to 360 joules of electrical energy (about as much as a 100 watt incandescent lamp uses in three seconds).

Preventative Maintenance

Preventative maintenance for the Defibrillator units consists of, electrical safety, followed by a physical inspection of the unit and all accessories.

List of Qualitative Tests for Defibrillator:

1. Chassis – verify physical integrity, cleanliness
2. Mount/Fasteners – verify physical integrity of mounts (wall, equipment, cart, etc.)
3. AC Plug – verify integrity
4. Line Cord – verify proper insulation and integrity
5. Strain Reliefs – verify physical integrity at both ends of line cord
6. Circuit Breaker/Fuse – verify integrity of external circuit breaker and/or value of external fuse
7. Cables – inspect cables of internal/external paddles, disposable defibrillation electrodes, and synchronizer cables
8. Connectors – examine all cable connectors
9. Paddles/Electrodes – verify physical integrity of paddles
10. Controls/Switches – verify proper operation; verify operation of redundant controls
11. Battery/Charger – verify operation & condition of battery/charger
12. Indicators/Displays – verify proper illumination and operation
13. Audible Signal – confirm appropriate volume and operation of volume controls
14. Labeling – verify presence and placement of all labels, placards, instruction cards, etc.
15. Accessories – verify availability of appropriate electrode and electrodes
16. Internal Discharge of Stored Energy – verify release of stored energy when power is turned off
17. Synchronizer – verify unit will not discharge when no ECG signal is present

Devices that are line powered:

1. Output Energy – (+/- 15% or 4J, whichever is greater) Test at 10J, 50J, 100J, 200J, 300J, 360J
2. Charge Time – (<15 Sec)
3. Max Energy – (10th Charge) (+/- 15% or 4J, whichever is greater)
4. Synchronizer Operation – Verify that “R” wave of ECG trace is illuminated (discharge <25 mSec after detecting ECG)
5. Waveform Analysis – Display discharge curve through the simulator on an oscilloscope. Verify that the waveform is within specifications per ANSI/AAMI DF2-1989.

AED Technology

Many of the new automated external defibrillators (AEDs) are also using biphasic technology.  AEDs have been created so that the layperson can easily administer defibrillation to a patient in cardiac arrest by following voice or visual instructions.  The AED device—or a manual defibrillator that has been programmed to AED mode—has the capability to analyze ventricular fibrillation in a patient and deliver shocks when it is appropriate.  Such devices deliver prompts and instructions for cardiopulmonary resuscitation.

Because it may be several months, or even years, before AEDs are actually used, it is important to have an effective maintenance process in place. During the time between uses, pads may expire and dry out, and batteries may die, so making sure AEDs are ready to be used at any time is paramount.  For this reason, most AEDs do a lot of self-checking.

Common Failures

Batteries

Batteries are an issue in AED packs due the battery losing an additional 20% of its useful life when the unit does its daily self-check every morning, so 40% of the battery’s useful life is depleted after 1 year, weather it is used or not. It is recommended the battery is replaced every 2 years.

Electrodes

The biggest thing to watch out for with defibrillators is the expiration of your electrode pads. Because of the chemical breakdown of the gel in the defibrillator pads, the manufacturers of AED pads cannot guarantee that the pads will have enough adhesion to work properly after a certain amount of time has passed.  Therefore, the pads have an expiration date to help ensure that sudden cardiac arrest patients have the best possible chance of survival.  Typical life expectancy of AED pads is between 18 and 30 months.  Therefore, it is vital to conduct routine maintenance and supply checks of all your AED units and medical emergency supply kits to ensure that your AED program is in compliance.  The risk of not doing so could cost someone his or her life.

The TRH Value

TRH Services is dedicated to providing safe and proper operation of all medical equipment, including defibrillators.  At TRH Services our expertise can help educate you on your defibrillators, as well as keep you up to date on your monthly maintenance to ensure your device is in perfect working order at all times. We also provide services offsite and onsite around Ontario.

References

Here is a brief list of some references used to write this blog:

• com Preventative Maintenance. (n.d.). Retrieved September 28, 2017, from http://www.aed.com/preventative-maintenance
• Maintaining Defibrillators. (n.d.). Retrieved September 28, 2017, from http://www.24x7mag.com/2007/05/maintaining-defibrillators/

Written By: Courtney Harley
Edited By: Tyler Hasenpflug CET