How an AED Works During Sudden Cardiac Arrest
What Happens During Sudden Cardiac Arrest?
When someone collapses in sudden cardiac arrest, the heart is no longer pumping blood effectively around the body. This often happens because the heart’s electrical system has become disrupted.
Instead of beating in a normal rhythm, the heart may start to quiver or beat chaotically. When this happens, oxygen-rich blood is not circulated properly, and the brain and other vital organs can quickly become starved of oxygen.
What Does an AED Do?
An automated external defibrillator, commonly known as an AED, is designed to check the electrical activity of the heart. Once the electrode pads are placed correctly on the casualty’s chest, the AED analyses the heart rhythm through those pads.
The AED looks for specific abnormal heart rhythms that may be treated with an electric shock.
Shockable Heart Rhythms
Some cardiac arrest rhythms are known as shockable rhythms. These include ventricular fibrillation and pulseless ventricular tachycardia.
In these situations, the heart’s electrical activity is disorganised. A controlled electrical shock from the AED can help stop this abnormal activity and give the heart the opportunity to restart in a normal rhythm.
When No Shock Is Advised
Not every cardiac arrest rhythm can be treated with defibrillation. Sometimes, the AED may analyse the heart rhythm and state that no shock is advised.
This does not mean the AED is faulty. It means the rhythm detected cannot be corrected with a shock. In this situation, the most important action is to continue high-quality CPR.
Why You Must Stand Clear During Analysis
During the AED analysis phase, it is vital that nobody touches the casualty. Movement, pressure on the chest, or continued contact can interfere with the AED’s ability to read the heart rhythm accurately.
This is why the AED will instruct rescuers to stand clear while it analyses the casualty.
Delivering a Shock
If the AED detects a shockable rhythm, it will either instruct the rescuer to press the shock button or deliver the shock automatically, depending on the type of AED being used.
The shock briefly stops the abnormal electrical activity in the heart. This gives the heart’s natural pacemaker a chance to restart a normal, effective rhythm.
Continue CPR After the Shock
After a shock has been delivered, the AED will usually instruct rescuers to resume CPR immediately.
CPR helps keep oxygenated blood moving to the brain and vital organs while the heart tries to regain an effective rhythm.
Key Point to Remember
The AED is designed to guide the rescuer throughout the emergency. It will only advise or deliver a shock when it is appropriate to do so.
By following the AED voice prompts and continuing CPR when instructed, rescuers are giving the casualty the best possible chance of survival.
