Which method is best for ensuring adequate ventilation during CPR?

The best method for ensuring adequate ventilation during CPR is the use of a bag-valve-mask device. This device allows for the delivery of positive pressure ventilation to the patient, which is critical in maintaining oxygenation and carbon dioxide elimination when spontaneous breathing is absent. The bag-valve-mask system provides a more reliable seal over the patient's airway and allows for delivering higher volumes of air compared to other methods like mouth-to-mouth resuscitation or using a pocket mask alone.

Additionally, when oxygen is used with a bag-valve-mask, it significantly enhances the effectiveness of ventilation, particularly in patients who may not be responding to the initial chest compressions alone. The ability to ventilate effectively can be crucial, especially in cases of respiratory arrest, where adequate oxygenation is vital for the patient's survival. While chest compressions are essential to maintain circulation, proper ventilation also plays a key role in maximizing the chances of a successful outcome during resuscitation efforts.