Final answer:
The first action for a second lifeguard arriving at a CPR scene is to confirm EMS has been called. They should then assist with high-quality chest compressions and ventilations without unnecessary interruptions. CPR is critical to maintaining circulation, particularly to the brain, before professional medical personnel arrive.
Step-by-step explanation:
When a second lifeguard arrives to assist with an ongoing CPR effort, the most appropriate first action for them would be to check to see whether EMS personnel have been called. This ensures that professional medical assistance is on the way, as continued CPR and advanced medical care are crucial for the victim's survival chances. It's also critical that the second lifeguard does not interrupt the first lifeguard's CPR efforts unless a switch is necessary due to fatigue or to enhance the quality of compressions or ventilations.
Performing high-quality chest compressions is essential during CPR. According to current standards, chest compressions should be at least 5 cm deep and at a rate of 100 compressions per minute. The goal is to manually compress the heart between the vertebrae and sternum to maintain blood circulation, particularly to the brain, to prevent neuronal death due to the lack of oxygen.
Moreover, when a victim is unconscious in the water, it is paramount to first remove them to stable ground before starting CPR, addressing the myth that CPR should begin in the water. Additionally, while automated external defibrillators (AEDs) are valuable tools, CPR should often be performed before their use to maintain blood flow until the heart can be restarted using the AED.