The most important action for successful resuscitation is to open the airway immediately. In the absence of sufficient muscle tone, the tongue or epiglottis will obstruct the pharynx or the larynx, respectively (fig. 10-2, Top). The tongue is the most common cause of obstruction in an unconscious victim.

Figure 10-2.-0pening the airway. Top: Airway obstruction produced by the tongue and epiglottis. Bottom: Relief by head tilt or chin lift.

Since the tongue is attached to the lower jaw, moving the jaw forward lifts the tongue and the epiglottis away from the back of the throat and opens the airway (fig. 10-2, Bottom). Also, either the tongue or the epiglottis, or both, may produce obstruction when negative pressure is created in the airway by inspiratory effort, causing a valve type of mechanism to include the entrance to the trachea. Opening the airway maybe all that is needed to relieve the obstruction and allow the victim to breathe.