What is the correct compressions-to-breaths ratio for an adult during CPR?

• A. 15 to 2
• B. 20 to 2
• C. 25 to 2
• D. 30 to 2

Answer: (D)

The main idea is the standard pattern used in adult CPR: 30 chest compressions followed by 2 rescue breaths. This ratio strikes a balance between delivering enough blood flow through compressions and providing enough oxygen through breaths without interrupting compressions too long. High-quality chest compressions should be performed at about 100–120 per minute and to a depth of about 2 inches (5 cm) in an adult. After you deliver 30 compressions, pause briefly to give two breaths, each lasting about one second, then resume compressions.

Other ratios aren’t used for adult single-rescuer CPR. For example, a 15:2 ratio is taught for some pediatric situations with two rescuers, but that context differs from adults. Ratios like 20:2 or 25:2 are not the standard guidelines for adult CPR.