Cardiac arrest is a sudden and unexpected event where the heart stops beating effectively. This can happen without warning, leading to a loss of consciousness and abnormal or absent breathing. Prompt intervention with Cardiopulmonary Resuscitation (CPR) and Automated External Defibrillators (AEDs) is crucial for improving survival chances. These two interventions play distinct, yet complementary, roles in managing a cardiac arrest emergency.
The Purpose and Mechanics of CPR
Cardiopulmonary Resuscitation (CPR) is an emergency procedure performed when someone’s heart has stopped beating, or is beating too inefficiently to circulate blood. Its purpose is to manually circulate oxygenated blood to the brain and other vital organs, delaying tissue damage and extending the window of opportunity for successful resuscitation.
CPR involves cycles of chest compressions and, if trained, rescue breaths. Compressions should be performed hard and fast in the center of the chest at a rate of 100 to 120 per minute and a depth of at least 2 inches for adults. Rescue breaths, given after every 30 compressions, help provide oxygen to the lungs. CPR is indicated when a person is unresponsive and not breathing normally.
The Purpose and Mechanics of Defibrillation (AEDs)
An Automated External Defibrillator (AED) is a portable electronic device designed to diagnose and treat certain life-threatening abnormal heart rhythms that cause sudden cardiac arrest. Its purpose is to deliver a controlled electrical shock to the heart, effectively “resetting” it to allow a normal rhythm to re-establish.
An AED works by analyzing the heart’s electrical activity through electrode pads placed on the chest. If it detects a “shockable” rhythm, such as ventricular fibrillation or pulseless ventricular tachycardia, it will advise or deliver a shock. An AED does not work for all types of cardiac arrest, such as asystole (a flatline rhythm). AEDs are designed for public use with clear voice prompts and visual instructions, making them accessible to individuals with minimal training.
The Critical Decision: When to Start CPR and When to Use an AED
Upon encountering someone who has collapsed and appears unresponsive, immediate action is necessary. First, check for responsiveness by shouting and tapping the person, and observe if they are breathing normally. If unresponsive and not breathing normally, call emergency medical services immediately.
Following the call for help, chest compressions (CPR) should be started without delay. Every minute without compressions reduces the chances of survival. If an AED is available, it should be brought to the scene and applied as soon as possible while CPR continues. The AED will analyze the heart’s rhythm and guide whether a shock is needed. CPR is the initial and continuous intervention, while an AED is a conditional intervention used in conjunction with CPR, if available and indicated by the device.
What to Do Until Emergency Services Arrive
Once CPR has begun and an AED is on the way or in use, continue high-quality chest compressions without interruption until professional medical help arrives. If an AED is being used, follow its voice prompts precisely; it will instruct when to pause compressions for rhythm analysis and shock delivery.
After a shock is delivered, CPR should resume immediately unless the AED advises otherwise or the person shows clear signs of life, such as normal breathing or movement. If multiple rescuers are present, they should switch roles approximately every two minutes to prevent fatigue and maintain the quality of compressions. Staying calm and focused throughout this period can improve outcomes.