Which statement best describes the action of chest recoil during CPR?

• A. Increases intrathoracic pressure
• B. Decreases venous return
• C. Draws air into the lungs by creating negative pressure during decompression
• D. Prevents air entry into the lungs

Answer: (C)

Chest recoil during CPR creates negative pressure in the intrathoracic cavity as the chest rises back to its normal position after a compression. This negative pressure pulls air into the lungs and also helps return blood to the heart, aiding ventilation and circulation. That’s why drawing air in during the decompression phase is the correct description. The compression phase, not the recoil, raises intrathoracic pressure; recoil does not decrease venous return, it actually increases it; and recoil does not prevent air entry, it facilitates it.