During chest compressions with positive pressure ventilation, which oxygen concentration should be used?

• A. Adjust to meet target oxygen saturation per pulse oximetry
• B. Increase to 100% as soon chest compressions are started
• C. Increase to 100% only if the heart rate hasn't risen after 30 seconds of coordinated chest compressions
• D. Use room air during chest compressions

Answer: (B)

During chest compressions with positive pressure ventilation, the priority is to maximize oxygen delivery to the still-perfused tissues. Using 100% oxygen provides the highest oxygen content to the lungs and, when the limited circulatory flow resumes, helps ensure the bloodstream carries as much oxygen as possible to the heart and brain. Starting with room air would underestimate oxygen delivery during this critical phase, and delaying high oxygen concentration until an HR response is observed would miss an opportunity to optimize perfusion-related oxygen delivery. After circulation is more stable and ROSC is achieved, oxygen can be titrated down to avoid hyperoxia based on pulse oximetry targets.