CPR and an Automated External Defibrillator (AED) are the most effective interventions for sudden cardiac arrest. CPR provides temporary circulation, while the AED delivers an electrical shock to reset a chaotic heart rhythm. Integrating these steps requires strict adherence to a specific sequence, particularly regarding the interaction between chest compressions and the device’s function. Following the AED’s exact prompts is necessary for the machine to correctly determine the appropriate action.
The Critical Stop: Why CPR Must Halt During Analysis
When the AED is ready to determine the heart’s electrical activity, it issues a clear, verbal command, usually “Analyzing heart rhythm. Do not touch the patient.” At this precise moment, all chest compressions and rescue breaths must stop immediately. This brief pause is non-negotiable and is standard protocol. Contact with the patient during analysis can be dangerous to the rescuer and counterproductive to the device’s function.
The AED detects a specific electrical signature indicating a shockable rhythm, such as ventricular fibrillation. If compressions continue, the electrical signals generated by the rescuer’s hands and chest movement interfere with the device’s ability to interpret the heart’s native rhythm. The analysis time is short, typically less than 10 seconds, ensuring the AED can make an accurate decision. Once analysis is complete, the AED will either advise a shock or prompt the rescuer to continue CPR.
Technical Necessity: How Motion Affects AED Readings
The primary reason for stopping compressions is to eliminate “motion artifact” from the electrocardiogram (ECG) reading. Chest compressions create significant movement and electrical interference that corrupt the faint electrical signal from the patient’s heart. This interference can look like a heart rhythm itself to the AED’s internal algorithm.
If the AED attempts to analyze a heart rhythm while compressions are ongoing, the motion artifact can mislead the device. This contamination can cause the AED to incorrectly identify a shockable rhythm as non-shockable, delaying necessary electrical therapy. Conversely, the artifact might add disorganized components to a non-shockable rhythm, causing the AED to mistakenly advise a shock. The device requires a clean signal to make a reliable decision regarding defibrillation.
The Full Sequence: Actions Immediately Before and After Analysis
The sequence of actions surrounding the analysis phase must be executed without hesitation to minimize interruptions in blood flow. Before the AED begins analysis, the rescuer must ensure the patient’s chest is exposed, dry, and the electrode pads are firmly attached. Upon the AED’s command to analyze, the rescuer must loudly announce “Clear!” to ensure all bystanders are not touching the patient.
If the AED advises a shock, the rescuer must repeat the “Clear!” command and visually confirm no one is in contact with the patient before pressing the shock button. If no shock is advised, or immediately after a shock is delivered, the AED will prompt the rescuer to resume CPR. Restart chest compressions without delay, beginning a new two-minute cycle of CPR before the next scheduled analysis. Rescuers should not pause to check for a pulse or wait for further instructions. Minimizing the pause before and after a shock directly improves the patient’s chance of survival.