What is the correct compression-to-ventilation ratio for adult CPR performed without an advanced airway?

In adult CPR performed without an advanced airway, the correct compression-to-ventilation ratio is 30 compressions to 2 breaths. This ratio is established in guidelines to maximize the effectiveness of chest compressions while ensuring adequate ventilation.

The reason this ratio is optimal is that it allows for a balance between maintaining oxygenation through breaths and promoting blood circulation via compressions. The chest compressions help to create a flow of blood that can deliver oxygen to the vital organs, whereas the breaths supplied during the pauses in compressions ensure that the blood being circulated is adequately oxygenated.

By using a ratio of 30 to 2, the rescuer can provide compressions more frequently, which is critical for maintaining blood flow during a cardiac arrest. The periodic breaths allow for the reintroduction of oxygen into the circulation, further enhancing the chances of survival and recovery.