To size an oropharyngeal airway (OPA), hold the device against the outside of the patient’s face with the flange at the corner of the lips and the tip reaching toward the earlobe. The correct OPA will extend from the lips to the angle of the mandible, which is the bony corner of the jawline just below the ear. This external measurement takes only a few seconds and is the standard method taught in basic and advanced life support courses.
The External Measurement Method
Pick up the OPA and hold it alongside the patient’s cheek. Place the flat end (the flange) so it sits right where it would rest against the lips. The curved tip should reach the angle of the mandible. That bony landmark is easy to find: run your fingers along the jawline toward the ear, and you’ll feel the jaw angle right below the earlobe.
Some training programs describe an alternative reference point: measuring from the corner of the mouth to the tragus, which is the small pointed flap of cartilage in front of the ear canal. Both landmarks approximate the same distance and both are considered acceptable. In practice, the corner-of-mouth-to-jaw-angle method is the one you’ll see referenced most often in clinical literature.
If you’re between two sizes, choose the smaller one. You can always swap it out, but starting smaller reduces the risk of the tip pushing too deep into the airway.
Available Sizes and Color Coding
OPAs come in a range of sizes, typically numbered 0 through 6 (or 000 through 5, depending on the manufacturer). Each size corresponds to a length in millimeters, generally from about 40 mm for the smallest infant size up to 120 mm for a large adult. Most manufacturers color-code the flanges so you can quickly identify sizes in an emergency:
- Infant and small child sizes are the shortest, often coded in colors like blue, black, or white depending on the brand.
- Older child and small adult sizes fall in the middle range, roughly 60 to 80 mm.
- Adult sizes run from about 80 mm to 120 mm and cover the majority of average to large adults.
Color coding is not universal across every manufacturer, so always confirm the printed size on the device rather than relying on color alone. In a well-stocked airway kit, you should have several sizes readily available because the external measurement is the only reliable way to match the OPA to the patient.
What Happens When the Size Is Wrong
An OPA that is too large can push the epiglottis (the flap that covers the windpipe during swallowing) down over the airway opening, creating the very obstruction you’re trying to prevent. It can also cause tissue trauma, bleeding, or trigger vomiting. An oversized OPA essentially converts a partial airway problem into a complete one.
An OPA that is too small won’t reach past the base of the tongue, which means the tongue can still fall back and block the airway. A short OPA may also slide deeper into the mouth and become difficult to retrieve, or it can push the tongue backward rather than holding it forward.
Either error, too large or too small, defeats the purpose of the device. That’s why the external measurement matters so much. It’s simple, fast, and prevents both problems.
Who Should and Shouldn’t Get an OPA
OPAs are designed for unconscious patients who have no gag reflex. The gag reflex test is straightforward: if the patient gags, coughs, or resists when you attempt to place the device, they still have enough protective reflexes to reject it, and forcing it can trigger vomiting or laryngospasm (a dangerous tightening of the airway muscles).
In general, patients with a Glasgow Coma Scale (GCS) score of 8 or below are candidates for an OPA because they are deeply unconscious and unlikely to have an intact gag reflex. Patients who are semiconscious, seizing, or who have any response to oral stimulation should not receive an OPA. A nasopharyngeal airway (NPA) is the alternative for patients who still have some level of consciousness.
How to Insert an OPA After Sizing
In adults, the standard technique is the rotation method. Open the patient’s mouth and insert the OPA with the tip pointing toward the roof of the mouth (upside down relative to its final position). Advance it about halfway into the oral cavity, then rotate it 180 degrees so the curve follows the natural shape of the tongue. Continue sliding it in until the flange rests against the lips.
The rotation is meant to prevent the tip from catching on the tongue and pushing it backward during insertion. Once rotated into position, the curved body of the OPA holds the tongue away from the back of the throat, keeping the airway open.
In children, many protocols skip the rotation entirely. Pediatric airways are softer and more easily damaged, so the preferred method is to use a tongue depressor to hold the tongue down and slide the OPA straight in with the curve already facing the correct direction. This avoids contact between the OPA tip and the delicate tissues of the palate.
Confirming Correct Placement
Once the OPA is in place, the flange should sit comfortably against the outside of the lips without protruding excessively or sinking in. Listen for air movement through the device. If the patient’s breathing improves and you can hear or feel airflow, the OPA is doing its job.
If breathing does not improve, or if you notice the OPA sitting too far out or too deep, remove it and try a different size. Reassess the external measurement. Keep in mind that an OPA alone doesn’t guarantee a clear airway. You still need to maintain a head-tilt/chin-lift or jaw-thrust maneuver and suction any secretions that accumulate. The OPA is one tool in airway management, not a complete solution on its own.