Final answer:
When a 53-year-old man collapses without responsiveness, check for breathing and pulse, then immediately start CPR and call for emergency help. If the individual shows signs of choking while conscious, use back slaps or the Heimlich maneuver.
Step-by-step explanation:
If you witness a 53-year-old man suddenly collapse and become unresponsive, the best next action after checking for responsiveness is to check for breathing and a pulse. If the man is not breathing or does not have a pulse, you should begin CPR immediately and call for emergency medical services. In a scenario where someone is unresponsive, it's critical to act promptly as every second without oxygen can lead to further harm or reduced chances of recovery.
If you are not trained in CPR, the emergency dispatcher can often guide you through the process until help arrives. Remember, if the person is showing signs of choking and is conscious, encourage them to cough, deliver back slaps, or perform the Heimlich maneuver if you are trained to do so. These actions could potentially dislodge an obstruction and allow them to breathe. If they become unconscious, follow the CPR procedures.