It is necessary to perform Cardiopulmonary Resuscitation (CPR) on someone who is also receiving care from an Automated External Defibrillator (AED). CPR involves providing chest compressions and rescue breaths to manually circulate oxygenated blood when the heart has stopped pumping effectively. An AED is a portable device that analyzes the heart’s electrical rhythm and delivers an electrical shock to correct a chaotic rhythm. The goal in a sudden cardiac arrest emergency is to combine continuous CPR with the life-saving capability of the AED as soon as one becomes available.
Integrating CPR and AED Use
The moment an AED arrives, the rescuer should continue chest compressions while a second person, if available, prepares the device. The AED pads must be placed directly onto the patient’s bare chest in the locations indicated by the device graphics (usually one on the upper right side of the chest and the other on the lower left side of the rib cage). Once the pads are attached and plugged into the AED, the device will begin analyzing the heart’s electrical rhythm.
CPR should only be paused briefly when the AED instructs everyone to stand clear for rhythm analysis or shock delivery. Minimizing this “hands-off” time is crucial, as blood pressure and oxygen levels drop rapidly during any interruption of compressions. Pauses in chest compressions should be limited to less than ten seconds for effective resuscitation. Many protocols encourage rescuers to continue compressions even while the AED is charging, pausing only at the moment the shock is delivered.
Before pressing the shock button, the rescuer operating the AED must loudly announce “clear” to ensure no one is touching the patient or connected equipment. This safety protocol prevents accidental electrical shock to rescuers or bystanders. Immediately after the shock is delivered, or if the AED advises “no shock advised,” the rescuer must resume chest compressions without delay.
Understanding the Roles of CPR and Defibrillation
CPR and defibrillation perform two distinct, yet complementary, functions. Chest compressions physically pump blood from the heart to the brain and other vital organs, effectively buying time for the patient. This mechanical circulation prevents tissue death and keeps the heart muscle supplied with enough oxygen to remain viable.
Defibrillation is the definitive treatment for the most common cause of sudden cardiac arrest, which is an electrical malfunction like ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT). In these conditions, the heart’s electrical activity is disorganized and chaotic, preventing the muscle from pumping blood. The controlled electrical shock from the AED momentarily stops all electrical activity, allowing the heart’s natural pacemaker to reset and potentially restore a normal rhythm.
CPR makes the heart more receptive to defibrillation. By circulating oxygenated blood, compressions improve the metabolic state of the heart muscle. A heart receiving high-quality CPR is more likely to respond successfully to a shock than one starved of oxygen for a prolonged period. This synergistic approach maximizes the patient’s chance of survival.
The Continuous Cycle of Care
Resuscitation is a continuous, alternating flow of activity, not a single event. Once the AED has delivered a shock, or advised against one, the rescuer must immediately begin another two-minute cycle of high-quality CPR. This cycle typically involves thirty chest compressions followed by two rescue breaths, repeated at a rate of 100 to 120 compressions per minute.
The AED will automatically prompt a pause after this two-minute period to re-analyze the heart rhythm. If the AED detects a shockable rhythm again, the rescuer will repeat the safety steps, deliver another shock, and immediately resume CPR for two minutes. If the AED advises “no shock advised,” the rescuer must still continue CPR, as this indicates a non-shockable rhythm like asystole.
The cycle of two minutes of CPR followed by rhythm analysis and potential shock continues until professional emergency medical services (EMS) arrive and take over care. Other situations that warrant stopping CPR include the patient showing obvious signs of life (such as breathing or movement), or if the rescuer becomes too exhausted to continue providing high-quality compressions. This rhythmic pattern of CPR and defibrillation is the current standard for managing sudden cardiac arrest outside of a hospital setting.