Final answer:
Check the individual's pulse for no longer than 10 seconds; use the carotid pulse for adults and the brachial pulse for children and infants. Immediately start CPR and call emergency services if there is no pulse or if you are unsure about the pulse.
Step-by-step explanation:
When you come across an unresponsive individual who is not breathing or only gasping, time is critical. First, you should check the individual's pulse for no longer than 10 seconds to minimize delay in starting resuscitation if needed. For adults, you should check the carotid pulse, located on the neck. For children and infants, it is appropriate to check a brachial pulse, located on the inside of the upper arm.
After determining there is no pulse or if you are unsure, begin cardiopulmonary resuscitation (CPR) immediately and call emergency services. AED use should be initiated as soon as it becomes available. CPR for an individual, especially if they have a condition like sleep apnea or have suffered from an event like carbon monoxide poisoning or near drowning, is critical and may save a life.