Cardiopulmonary Resuscitation (CPR) and the Automated External Defibrillator (AED) are the two immediate, life-saving interventions for a person experiencing sudden cardiac arrest. CPR manually circulates blood and oxygen to the brain and heart, while the AED delivers an electrical shock to reset the heart’s rhythm. Coordinating the arrival of an AED with ongoing CPR is a swift transition that must be managed with precision. The goal is to move seamlessly from one life-support measure to the other to maximize the person’s chance of survival.
The Critical Goal: Minimizing Compression Pauses
The answer to whether CPR should stop when an AED arrives is a firm no; compressions must continue until the AED is fully prepared to analyze the heart’s rhythm. This action is guided by the need to maintain coronary perfusion pressure (CPP), which drives blood flow to the heart muscle during chest compressions. A pause in compressions causes a rapid drop in this pressure, requiring several compressions to build it back up. Studies have shown that even short interruptions, ideally kept to less than 10 seconds, significantly reduce the effectiveness of the resuscitation effort. Continuous compressions are important because a minimum CPP of about 15 mmHg is necessary for successful defibrillation.
Integrating the AED: Step-by-Step Pad Application
When the AED arrives, a rescuer should immediately power it on and follow its voice prompts while chest compressions continue. If two rescuers are present, the one not performing compressions should handle the AED preparation to ensure no time is lost. The patient’s chest must be quickly exposed and dried, if necessary, to ensure the adhesive pads stick correctly. The defibrillator pads are then applied to the patient’s bare skin: one pad on the upper right side of the chest, and the other pad on the lower left side of the rib cage. The brief pause required to place the pads and connect them to the AED unit must be executed as swiftly as possible, ideally by coordinating the stop with the end of a CPR cycle.
The Analysis and Shock Delivery Phase
Once the pads are connected, the device automatically begins to analyze the heart’s electrical rhythm, and this is the only time chest compressions must stop. The rescuer operating the AED must loudly command, “Clear!” to ensure that no one is touching the patient, preventing accidental electrical shock. The AED takes a few seconds to determine if the rhythm is shockable, such as ventricular fibrillation. If the AED advises a shock, the rescuer again announces “Clear!” before pressing the shock button, keeping all hands off the patient. If the AED advises against a shock, compressions must be restarted immediately to minimize the “hands-off” time.
Immediate Action After Defibrillation
Regardless of whether a shock was delivered, the rescuer must immediately resume Cardiopulmonary Resuscitation without checking for a pulse. The goal is to immediately begin chest compressions to circulate the blood that may have been momentarily restored by the shock or to continue perfusing the heart. The AED protocol directs rescuers to provide approximately two minutes of high-quality CPR before the device automatically reanalyzes the heart rhythm. The AED pads must remain firmly attached to the patient’s chest, and the device should not be turned off, as it will continue to guide the rescue effort. This cycle of two minutes of CPR followed by rhythm analysis continues until emergency medical services arrive and take over care.