Final answer:
For a witnessed cardiac arrest, one should immediately start CPR and use an AED, if available. In an unwitnessed case, check for responsiveness, call for help, then commence CPR. Drowning victims should be removed from the water before beginning CPR.
Step-by-step explanation:
When you witness a cardiac arrest, immediate action is critical. The first few minutes are vital for the survival and recovery of the individual. If a cardiac arrest is witnessed, you should call for help and begin CPR (cardiopulmonary resuscitation) immediately. If an automated external defibrillator (AED) is available, it should also be used without delay. In an unwitnessed cardiac arrest, check for responsiveness, call for emergency help, and then start CPR quickly.
For drowning victims, it is crucial to remove the person from the water before starting CPR. This is because CPR is ineffective in water and must be performed on stable ground for it to be effective. Moreover, time is of the essence since brain cells start dying within minutes due to lack of oxygen. Even in cases where the heart has stopped, starting CPR within minutes can significantly increase the chances of survival, especially in children drowning in cold water where there have been instances of full recovery after prolonged periods underwater.
In summary, the key actions to remember are calling for emergency help, starting CPR right away, and using an AED if available. These actions, performed in the critical initial minutes of a cardiac emergency, can greatly improve the chances of survival and recovery.