Final answer:
In an emergency where the victim is unresponsive and pulseless, start Hands-Only CPR and use an automated external defibrillator (AED) if available, while calling for emergency help immediately.
Step-by-step explanation:
If you are the first responder and find a victim who is unresponsive, pulseless, and has vomited, and you are uncomfortable with performing mouth-to-mouth ventilation, the best approach would be to start Hands-Only CPR (CPR without rescue breaths). This involves providing chest compressions at a rate of 100 to 120 compressions per minute. Ensure the victim is lying flat on their back on a firm surface, interlace your fingers, place the heel of your hand on the center of the victim's chest, and push hard and fast. It is also critical to call for emergency medical help immediately.
In situations where an automated external defibrillator (AED) is available, it should be used as soon as possible following the device's instructions. An AED is designed to guide rescuers through the process, so even untrained bystanders can use it effectively. If there is another person present, you can delegate them to call emergency services and fetch the AED while you start chest compressions.