Effective Use of Oropharyngeal and Nasopharyngeal Airways

Oropharyngeal and nasopharyngeal airways are assistive devices that can be used to obtain/maintain an open airway. An oropharyngeal airway (OPA) is also known as an oral airway or Guedel-type airway or simply a Guedel airway (named after the original designer, Arthur Guedel). A nasopharyngeal airway (NPA) is also known as a nasal airway, NPAT (nasopharyngeal airway tube), or nasal trumpet. Either device may be used depending on the indication for use and patient condition.

Function and Indications
The oropharynx is the primary site of upper airway obstruction in comatose or anesthetized patients. This is because the tongue and jaw muscles cause the tongue and epiglottis to move posteriorly, potentially obstructing the airway. Additionally, comatose or anesthetized patients are at increased risk for upper airway collapse because lower central drive decreases the activity of the pharyngeal dilator muscles. The OPA helps relieve these potential obstructions because it moves the tongue and hypopharyngeal structures anteriorly, improving airway patency. 

As mentioned above, the primary indication for the use of an OPA is when the patient is at risk for airway obstruction due to lax upper airway muscles or tongue obstruction of the airway. For example, if you perform a head tilt-chin lift maneuver or jaw thrust on a patient to open their airway but are unable to successfully ventilate the patient, an OPA may be placed. Additionally, if you manually ventilate the patient, you may inadvertently push down on the patient’s jaw and block their airway. Proper use of an OPA can prevent this unintended blockage from occurring. Due to the depth of a properly placed OPA, it should only be used in unconscious patients to prevent vomiting and vomiting of gastric contents.

Nasopharyngeal airways are also used to maintain an open airway and can be used in awake or semi-conscious patients. For example, semi-conscious patients may require an NPA because they are at risk for airway obstruction, but an OPA cannot be placed due to an intact gag reflex. Polyvinyl chloride nasopharyngeal airway tubes (NPATs) are readily available and are often used by anesthesia providers during induction or immediately postoperatively to help prevent airway obstruction. 8 NPAs may also be used in patients who clench their teeth, making oral airway insertion difficult, and in semi-conscious patients who require frequent nasotracheal suctioning.

Insertion and Procedure
While the airway is simple to use, choosing the right size is important. If the airway is too small, its distal end may be obstructed by the tongue, resulting in hypoventilation. Radiographic assessment of the position of the OPA also suggests that the distal end of the airway may become lodged in the vallecula or obstructed by the epiglottis. If the OPA is too large, there is a risk of trauma to surrounding laryngeal structures and even possible laryngospasm. 

There are two common facial measurements used to determine the appropriate size OPA: the distance from the maxillary incisors to the mandibular angle, and the distance from the corner of the mouth to the mandibular angle.