Automated External Defibrillator (AED)
When a patient experiences a cardiac arrest, there are several things that we should do to give them the best chance of survival. Calling for help so we aren’t trying to work a code alone, starting good High Quality CPR to circulate blood to the vital organs, and defibrillating as soon as possible if the patient’s in a shockable rhythm. To aid in the rapid delivery of a shock, an Automated External Defibrillator (AED) should be used in settings where a full monitor/defibrillator isn’t available. The use of an AED to quickly deliver a life-saving shock is today’s Pass ACLS tip topic.
Why Use an AED?
Performing good CPR, and delivering a shock as soon as possible to a patient in Ventricular Fibrillation or pulseless V-Tach are the two most critical interventions that have been shown to increase survival after cardiac arrest.
The most common rhythm a person is in during the first few minutes of cardiac arrest is Ventricular Fibrillation. Immediately delivering a shock to a monitored patient that goes into V-Fib has about a 90% chance of successfully converting to a perfusing rhythm. We lose approximately 3-10% chance for successful conversion for every minute that passes. This is why we should deliver a shock as soon as possible when a patient is in a shockable rhythm.
To help with the rapid delivery of a life-saving shock, an AED should be used when a full monitor/defibrillator isn’t available. AEDs are small, simple to use, less expensive than a monitor/defibrillator, and (most importantly) are effective.
Contraindications for AED Use
To ensure safety, AEDs should not be used on:
- patients with a pulse; or
- patients in standing water.
Automated External Defibrillator (AED) Use
Until an ALS ambulance arrives for out-of-hospital arrests (OHSCA), or the hospital code team arrives with a monitor/defibrillator, an AED can be used to work a code.
First and most important is that an AED is no good until it gets to the patient’s side. Upon discovering an (unexpected) unresponsive patient, Healthcare providers and lay persons alike should call for help. Doing CPR alone sucks! If the patient is an adult and you’re alone, or you don’t have the ability to yell or call for assistance, you may need to leave the patient shortly to call for help and grab an AED if one is available. In most cases help will be available so we should begin CPR, starting with chest compressions, until help arrives with the AED.
Once at the patient’s side, the AED should be:
- turned on;
- cables attached; and
- pads placed while fast and deep chest compressions continue.
After the second pad is placed, most AEDs will give a verbal instruction to stand clear while it analyzes the rhythm. Stop CPR while the AED is analyzing. If a shock is advised, the AED will say so and begin charging. Although not possible with every AED, we should resume chest compressions while we’re waiting for the AED to charge. The person working the AED must double check to ensure nobody is touching the patient before pushing the button to deliver a shock. If anyone on the team sees something potentially unsafe, they should speak up! Once a shock is safely delivered, the AED will give instructions to continue CPR. We should resume CPR starting with chest compressions.
Some AEDs have a built in metronome to help the compressor deliver compressions at a rate of 100-120 per minute. AEDs also have a built in timer, so after two minutes, it will advise to stop CPR so a pulse and rhythm can be checked.
As long as the AED recognizes a shockable rhythm it will continue to advise a shock every two minutes and we’ll follow the left side of the adult cardiac arrest algorithm. If no shock is advised for a pulseless patient, we’ll assume asystole or PEA and follow the right side of the algorithm.
