When should lifeguards use CPR?

Lifeguards should use CPR when the victim is not breathing or has no pulse. This criterion is critical because CPR, or cardiopulmonary resuscitation, is a life-saving technique aimed at restoring oxygenated blood flow to the brain and other vital organs when they are deprived of such during a cardiac arrest or respiratory failure.

In situations where a person has stopped breathing or has no detectable pulse, immediate CPR can help maintain blood circulation and oxygenation until advanced medical help can arrive. Chest compressions and rescue breaths are integral components of CPR that serve to keep blood circulating and provide essential oxygen to the lungs, significantly increasing the chances of survival and reducing the risk of long-term brain damage.

The other options suggest scenarios that do not align with the necessary criteria for initiating CPR, such as using it only under specific conditions that do not encompass the full range of emergencies where CPR could be life-saving.