Oropharyngeal Airways (OPA) and Nasopharyngeal Airways (NPA) are essential tools for maintaining an open airway in individuals with breathing difficulties. They prevent the tongue or other soft tissues from blocking the airway. Correct measurement and utilization are crucial for effectiveness and patient safety, as precise anatomical measurements directly impact successful airway management.
Understanding Oral and Nasal Airways
An Oropharyngeal Airway, an OPA, is a curved, rigid device inserted into the mouth to prevent the tongue from obstructing the upper airway. This often occurs in unconscious patients when jaw muscles relax, allowing the tongue to fall backward. OPAs are indicated for unresponsive individuals without an intact gag reflex, as insertion can trigger vomiting and aspiration in conscious patients.
A Nasopharyngeal Airway, an NPA, is a soft, flexible tube inserted through the nasal passage into the posterior pharynx. It is useful when an OPA cannot be used, such as in conscious or semi-conscious patients requiring airway support. NPAs are better tolerated by patients with an intact gag reflex and are beneficial when the mouth is difficult to open (e.g., due to trismus or angioedema).
Why Accurate Sizing Matters
Accurate sizing of OPA and NPA devices is paramount; improper sizing leads to significant complications. An OPA that is too small may fail to effectively move the tongue, worsening airway obstruction and hindering adequate ventilation. Conversely, an OPA that is too large risks trauma to oral structures (e.g., soft palate, teeth). It can also push the epiglottis down, obstructing the airway, or stimulate a gag reflex, leading to vomiting and aspiration.
For NPAs, a device that is too short may not clear the airway, while an excessively long one can press against the epiglottis or posterior pharyngeal wall, causing obstruction or stimulating a gag reflex, leading to vomiting and aspiration. Serious complications like nasal bleeding, pharyngeal ulcers, or intracranial placement (in cases of basilar skull fractures) can occur if the NPA is too long or improperly inserted.
Measuring an Oropharyngeal Airway
Measuring an Oropharyngeal Airway requires precise technique for proper function and to minimize adverse effects. One common method involves holding the OPA against the patient’s face: the tip should align with the corner of the mouth, and the flange (the flat part outside the mouth) should reach the angle of the jaw, just below the ear. Some guidelines also suggest measuring from the center of the top front teeth to the angle of the mandible to confirm appropriate length.
Another approach places the OPA tip at the earlobe, with the flange aligning with the corner of the mouth. Selecting the correct size before insertion is important, as an incorrect length can worsen airway obstruction or cause trauma. Avoid common pitfalls like forcing the OPA, which can injure teeth or soft tissues, or failing to rotate it correctly during insertion, which might leave the tongue obstructing the airway.
Measuring a Nasopharyngeal Airway
Measuring a Nasopharyngeal Airway relies on specific anatomical landmarks for optimal fit and function. The most common method for determining length is to measure from the tip of the nose to the earlobe. Another technique measures from the tip of the nose to the angle of the jaw. The chosen NPA should reach this distance without being excessively long.
Beyond length, diameter is also important. The selected diameter should allow the tube to pass through the nostril without blanching or excessive resistance. For adults, NPA sizes range from 6 to 9 mm in internal diameter (6-7 mm for women, 7-8 mm for men). The right nostril is preferred for insertion due to the NPA’s natural curve and how its bevel opens into the pharynx. If resistance is encountered, use a smaller size or the other nostril; force should never be applied.