When someone is unconscious, all muscles are relaxed. If they are left lying on their back, the tongue, which is attached to the back of the jaw, falls against the back wall of the throat and blocks air from entering the lungs. Other soft tissues of the airway may worsen this obstruction.

The mouth falls open, but this tends to block, rather than open, the airway.

The unconscious person is further at risk because they are unable to swallow or cough out foreign material in the airway. This may cause airway obstruction and foreign material may enter the lungs. For this reason, the rescuer should not give an unconscious person anything by mouth and should not attempt to induce vomiting.

In an unconscious person, care of the airway takes precedence over any injury, including the possibility of spinal injury. All who are unconscious should be handled gently with no twisting or bending of the spinal column and especially the neck. If it is necessary, move the head gently to obtain a clear airway. Where possible, an assistant should support the head when an injured person is being moved.

A casualty should not be routinely rolled onto the side – leave them in the position in which they have been found. The exceptions to this would be where the airway is obstructed with fluid (water or blood) or matter (sand, debris, vomit). Here, the person should be promptly rolled onto their side to clear the airway.

After rolling onto their side, the mouth should be opened, and the head turned slightly downwards to allow any obvious foreign material (e.g., food, vomit, blood and secretions) to drain. Loose dentures should be removed, but well-fitting ones can be left in place.

If the airway becomes compromised during resuscitation, promptly roll the person onto their side to clear the airway. Once the airway is clear, reassess for responsiveness and normal breathing, then begin resuscitation as appropriate following the Basic Life Support Flowchart.

Regurgitation is the passive flow of stomach contents into the mouth and nose. Although this can occur in any person, regurgitation and inhalation of stomach contents is a major threat to an unconscious person. It is often unrecognised because it is silent and there is no obvious muscle activity. Vomiting is an active process during which muscular action causes the stomach to eject its contents.

In resuscitation, regurgitation and vomiting are managed in the same way, by promptly positioning the person on their side and clearing the airway.  If the person begins to breathe normally, they can be left on their side with appropriate head tilt. If not breathing normally, the person must be rolled on their back and resuscitation commenced.