What is the appropriate compression-to-ventilation ratio for an adult patient in cardiac arrest?

The appropriate compression-to-ventilation ratio for an adult patient in cardiac arrest is 30:2. This ratio is established based on guidelines that emphasize the importance of high-quality chest compressions as the primary method of creating blood flow during cardiopulmonary resuscitation (CPR).

In this ratio, 30 chest compressions are given followed by 2 rescue breaths, which helps ensure that there is adequate circulation and oxygenation of the patient's blood. The focus on delivering compressions at a rate of 100 to 120 per minute and providing ventilations helps to maximize the chances of survival until advanced medical help arrives.

The other ratios, while used in some specific situations, are not the standard for adult CPR in cases of cardiac arrest. 15:2 might be used in a scenario involving two rescuers with the emphasis on performing more compressions but is typically not the recommended approach for just one rescuer. Similarly, the 20:2 ratio is not a standard recommendation, and a 1:1 ratio is not feasible as it would not provide sufficient compressions, which are crucial for maintaining circulation. Thus, 30:2 is the correct and best practice for adult cardiac arrest situations.