What is the first step in performing mouth-to-mouth ventilation on an adult?

The first step in performing mouth-to-mouth ventilation on an adult is to hold the airway open with the head tilt-chin lift maneuver. This technique is crucial because it helps to ensure that the airway is unobstructed, allowing air to flow freely into the lungs during ventilation. By tilting the head back and lifting the chin, you are effectively repositioning the tongue and opening up the airway, which is essential for delivering effective breaths.

Once the airway is opened, it becomes possible to create an effective seal around the mouth and to deliver breaths properly. Without this initial step, any further actions, such as sealing the lips or delivering breaths, may not be effective if the airway is not clear. Properly securing the airway is fundamental to successful resuscitation efforts.