What is the recommended compressions-to-ventilations ratio in adult CPR?

• A. 15:2
• B. 20:2
• C. 30:2
• D. 30:4

Answer: (C)

The main idea here is balancing blood flow with oxygen delivery during adult CPR. The standard cycle is 30 chest compressions followed by 2 rescue breaths. This pattern maximizes perfusion because keeping compressions frequent maintains blood flow to the heart and brain, while the 2 breaths provide enough oxygen without causing long stoppages in compressions. If you increase the number of breaths (for example, 4 breaths) you cause longer pauses between compressions, which reduces perfusion. If you reduce breaths too much or skip them, oxygen delivery suffers. The 30:2 ratio is the widely taught guideline for adult CPR unless an advanced airway is in place, which changes ventilation timing.