1. Verify scene safety. If you encounter a potential cardiac arrest victim, first make sure the scene is safe for both the rescuer and the victim.
2. Check responsiveness. Get help. Check for responsiveness. First tap the victim and shout “HEY! HEY! Are you OK?” If they do not respond, shout for help. Activate the emergency response system.
3. Assess for breathing and pulse. Check for absent or abnormal breathing by watching the chest for movements for 5 to 10 seconds. Simultaneously check for a pulse for a minimum of 5 seconds—but no more than 10 seconds. To perform a pulse check in an infant, palpate a brachial pulse. In a child, palpate a carotid or femoral pulse. It’s important to minimize delay in starting CPR, so take no more than 10 seconds to assess the patient.
   • If the victim has a pulse and is breathing normally, monitor them until emergency responders arrive.
   • If the victim has a pulse but is breathing abnormally, maintain the patient’s airway and begin rescue breathing. Administer one breath every 3 to 5 seconds, not exceeding 12 to 20 breaths per minute. Check the patient’s pulse every 2 minutes. Add compressions if the pulse is less than or equal to 60 beats per minutes with signs of poor perfusion. If at any point there is no pulse present, begin administering CPR. After 2 minutes of rescue breathing, activate the emergency response system if you haven’t already done so.
4. Witnessed sudden collapse? If the victim is not breathing and has no pulse, and the collapse was sudden and witnessed, leave the victim to activate the emergency reponse system and retrieve the AED.
5. Begin CPR. If a pulse is not identified within 10 seconds, and the collapse was not witnessed, immediately begin administering CPR, starting with chest compressions. Compressions should occur at a rate of 100 to 120 compressions per minute, at one third the depth of the chest. For an infant, use the 2-finger chest compression technique. For a child, use one or two hands, whatever is needed to provide adequate compression depth. Use a compression-to-ventilation ratio of 30 compressions to 2 breaths.
6. Activate emergency response and retrieve AED. After 2 minutes of CPR, if the emergency response system has still not been activated and you are still alone, leave the victim to activate the emergency response system and retrieve the AED. Use the AED as soon as it is available.
   • If the AED advises that the patient has a shockable rhythm, follow the prompts, clear the patient, and deliver the shock. Immediately resume CPR, starting with compressions, for 2 minutes or until the AED prompts you to check the patient’s rhythm again. Compressions should not be discontinued for more than 10 seconds. Continue providing CPR and following the AED prompts until ALS providers can take over or the victim begins to breathe, move, or react.
   • If the AED advises that the patient’s rhythm is nonshockable or no shock is advised, immediately resume CPR, starting with compressions.. Continue CPR for 2 minutes, or until the AED prompts you to check the patient’s rhythm again. Compressions should not be discontinued for more than 10 seconds. Continue providing CPR and following the AED prompts until ALS providers can take over or the victim begins to breathe, move, or react.