In the Field
OPA is the simpler airway adjunct that is also more restricted in use. If the casualty cannot tolerate having a plastic object pushed against the back of the throat, they need NPA, not OPA. The presence of a gag reflex is the disqualifier. In the unconscious trauma casualty without TBI and without airway-protecting reflexes, OPA holds the tongue forward, opens the oropharynx, and is the bridge to BVM ventilation. Sizing matters: too short does not lift the tongue effectively; too long can push the tongue or epiglottis into the airway and worsen obstruction.
Common Mistake
Inserting an OPA in a casualty who still has a gag reflex. Vomiting and aspiration follow, and the airway is now worse than before the intervention. The other mistake is incorrect sizing. The correct length corresponds to the distance from the corner of the mouth to the angle of the mandible (or to the earlobe). Too short leaves the tongue obstructing; too long pushes the epiglottis down.
Technical Detail
OPA design: rigid plastic, curved to follow the palate and oropharynx. Available sizes range from 40 mm (infant) to 110 mm (large adult), measured from flange to distal tip. Sizing method: distance from corner of mouth to angle of mandible, or corner of mouth to earlobe. Insertion: upside-down technique (insert with curve pointing toward palate, rotate 180 degrees as it passes the tongue); pediatric technique (insert in anatomic orientation with tongue depressor assistance to avoid pushing tongue posteriorly). Used in unconscious casualties without gag reflex; contraindicated when gag reflex present. May be left in place during BVM ventilation, supraglottic airway placement, and endotracheal intubation. TCCC doctrine specifies NPA over OPA for tactical use because NPA is better tolerated in semi-conscious casualties with depressed but present gag reflex - operationally the more common presentation in tactical trauma.
