Rescue Breathing & Ventilation
Ventilation restores oxygen and removes carbon dioxide, but too much ventilation is harmful. The BLS exam tests both how to deliver an effective breath and the exact rates for a victim who has a pulse but is not breathing adequately.
Delivering an effective breath
Give each rescue breath over about 1 second and deliver only enough volume to produce a visible chest rise. Use a barrier device or bag-mask when available; with a bag-mask, an E-C clamp technique holds the seal. Avoid excessive ventilation — too many breaths or too large a volume raises intrathoracic pressure, reduces venous return and cardiac output, and pushes air into the stomach, causing gastric inflation and vomiting. If the first breath does not make the chest rise, reopen the airway with a head-tilt/chin-lift and try again.
Rescue breathing rates when a pulse is present
When a victim has a pulse but is not breathing or is breathing inadequately, give rescue breaths without compressions. For an adult, give 1 breath every 6 seconds (about 10 breaths per minute). For an infant or child, give 1 breath every 2 to 3 seconds (about 20 to 30 breaths per minute), reflecting their higher metabolic demand. Recheck the pulse about every 2 minutes; if the pulse is absent or the heart rate in an infant/child is below 60 with poor perfusion, begin chest compressions.