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Effective Use of Oropharyngeal and Nasopharyngeal Airways

Oropharyngeal and nasopharyngeal airways are adjuncts that can be used to obtain/maintain an open airway. An oropharyngeal airway (OPA) is also known as an oral airway or Guedel pattern airway (named after the original designer Arthur Guedel)2. The nasopharyngeal airway (NPA) is also called a nasal airway, NPAT (nasopharyngeal airway tube), or nasal trumpet. Either device can be used depending on the indications for use and patient circumstances.

The American Red Cross. Airways Adjuncts. http://www.redcross.org/images/MEDIA_CustomProductCatalog/m4240191_AirwayAdjunctsFactandSkill.pdf Accessed January 2019.

Function and Indication

The oropharynx is the primary site of upper airway obstruction in unconscious or anesthetized patients. This is because the tongue and muscles of the jaw causing posterior movement of the tongue and epiglottis, which may obstruct the airway5. Furthermore, the risk of upper airway collapse increases in unconscious or anaesthetized patients, because a low central drive decreases the activity of the pharyngeal dilator muscles3. An OPA is helpful in relieving these potential obstructions as it moves the tongue and hypopharyngeal structures forward, improving airway patency3.

As described, the main indication for use of an OPA is if a patient is at risk of airway obstruction due to relaxed upper airway muscles or blockage of the airway by the tongue. For example, if you perform a head tilt-chin lift maneuver or jaw thrust on a patient to open their airway and are not able to ventilate the patient successfully, placement of an OPA is indicated. In addition, if you are manually ventilating a patient you may inadvertently push down on the patient’s chin and obstruct their airway. The appropriate application of an OPA can prevent this unintended obstruction from occurring. Due to the depth of an appropriately placed OPA, they can only be used in the unconscious patient to prevent gagging and vomiting of gastric contents.

Nasopharyngeal airways are also used to keep the airway open and can be used with patients who are conscious or semi-conscious. For example, semi-conscious patients may need an NPA because they are at risk for airway obstruction but cannot have an OPA placed due to an intact gag reflex. Polyvinyl chloride nasopharyngeal airway tubes (NPATs) are readily available and are commonly used by anesthesia providers for patients either during induction or in the immediate postoperative period to help prevent obstruction of the airway8. NPAs may also work well for patients who are clenching their jaw, which makes inserting an oral airway difficult, and for those who are semi-conscious and need frequent nasal-tracheal suctioning.

Insertion and Procedures

Although airways are simple to use, it is important to select an appropriate size. If the airway is too small, its distal end will be obstructed by the tongue, resulting in inadequate ventilation3. Radiographic assessment of the position of OPAs also demonstrated that the distal end of the airway may lodge in the vallecula or can be obstructed by the epiglottis5. If the OPA is too large, there is a risk of traumatic injury to the surrounding laryngeal structures3, and possibly laryngospasm5.

There are two common facial measurements recommended for determining the proper sized OPA: the distances between the maxillary incisors to the angle of the mandible, and the distance from the corner of the mouth to the angle of the mandible.

Kim, J.K., Kim, S.H., Min, N.H., & Park, W.K. (2016). Determination of the appropriate sizes of oropharyngeal airways in adults: correlation with external facial measurements. European Journal of Anesthesiology, 33. 936-942.

A 2016 study determined the most appropriate measurement tool are as follows4:

In the maxillary incisors to the angle of the mandible group, there was clear manual ventilation through the oropharyngeal airway in all patients, whereas partially obstructed ventilation was observed in 6% of patients in the corner of the mouth to the angle of the mandible group. In the maxillary incisors to the angle of the mandible group, mechanical ventilation through the oropharyngeal airway was adequate in all patients but in the corner of the mouth to the angle of the mandible group, inadequate ventilation was observed in 7% patients. In the maxillary incisors to the angle of the mandible group, the endoscopy did not identify any patient with complete obstruction of the airway by the tongue but in the corner of the mouth to the angle of the mandible group, 40% of patients had complete obstruction by the tongue. In the maxillary incisors to the angle of the mandible group, the tip of the airway passed beyond the tip of the epiglottis in 22% of patients, in contrast, none of the airways in the corner of the mouth to the angle of the mandible group passed beyond the tip of the epiglottis.

These results indicate that to obtain adequate ventilation in conjunction with an acceptable endoscopic view, the maxillary incisors to the angle of the mandible measurement for an OPA is more acceptable.

Before inserting the airway, clear the mouth of secretions such as vomit, blood, or sputum using a suction catheter. Place the oral airway in the mouth with the curved end towards the hard palate or the roof of the mouth. As you are inserting the device and it approaches the posterior pharynx, rotate the device 180 degrees into the correct position. Another option is to use a tongue blade to gently depress the tongue caudally, and then place the OPA with the curved portion facing the tongue from the beginning.

After the oral airway is inserted, the flange of the device should rest on the patient’s lip. Be sure to assess the OPA frequently to prevent the upper and/or lower lip from getting pinched or displaced. There is no need to secure the device with tape. Be sure to suction the airway as needed.

When using a nasopharyngeal airway, selecting the proper size is also important. If the NPA is too long, it will either enter the larynx and irritate the coughing and gag reflexes, or be inserted into the vallecula, possibly causing an airway obstruction1. If too short, the NPA will fail to separate the soft palate and dropped tongue base from the pharynx1. To determine the correct size, measure from the tip of your patient’s nose to the tip of their earlobe. In addition, choose an NPA which has a diameter a little smaller than the patient’s nares. The distal tip of the NPA is properly placed beyond the tongue base but should not be in contact with the epiglottis. It has been suggested that the ideal position for the NPA tip is 1 cm above the epiglottis7. The NPA’s length is a more important factor than its diameter in selecting the appropriate size of NPA6.

An NPA should be inserted with the bevel pointing towards the septum and following the natural curvature of the floor of the nasal cavity as it is advanced. Adequate application of a water-based lubricant to the outside of the NPA can facilitate a less traumatic insertion. Once the device is inserted, the flange should rest on the nostril opening.

Contraindications

Using an oropharyngeal airway on a conscious patient with an intact gag reflex is contraindicated. Patients that can cough still have a gag reflex and an OPA should not be used. If the patient has a foreign body obstructing the airway, an OPA should also not be used. NPAs should not be used on patients who have nasal fractures or an actively bleeding nose. In some cases, slight bleeding may occur when you insert the airway, which can be suctioned or wiped away.

Tips

  • Be gentle when inserting either an oropharyngeal or nasopharyngeal airway.
  • Avoid forcing an oropharyngeal airway, which can lead to trauma to the lips and tongue.
  • Use caution when twisting the oropharyngeal180 degrees to avoid trauma along the hard palate.
  • Use a water-soluble lubricant when inserting a nasopharyngeal airway.
  • If resistance is felt during insertion of a nasopharyngeal airway, stop and try the other naris.

References

  1. Cherng, C.H., & Huang, Go-Shine. A modified lengthened nasopharyngeal airway. Journal of Clinical Anesthesia, 2013;25:240-246.
  2. Guedel A. E. J. Am. Med. Assoc. 1933;100:1862 (reprinted in “Classical File”, Survey of Anesthesiology 1966;10:515).
  3. Kim, H.J., Kim, S.H., Min, J.Y., & Park, W.K. Determination of the appropriate oropharyngeal airway size in adults: Assessment using ventilation and an endoscopic view. American Journal of Emergency Medicine 2017;35:1430-1434.
  4. Kim, J.K., Kim, S.H., Min, N.H., & Park, W.K. Determination of the appropriate sizes of oropharyngeal airways in adults: correlation with external facial measurements. European Journal of Anesthesiology 2016;33:936-942.
  5. Kim, S.H., Kim, J.E., Kim, Y.H., Kang, B.C., Heo, S.B., Kim, C.K., & Park, W.K. An assessment of oropharyngeal airway position using a fiberoptic bronchoscope. Anesthesia 2014;69:53-57.
  6. Roberts K, Whalley H, Bleetman A. The nasopharyngeal airway: dispelling myths and establishing the facts. Emerg Med J 2005;22:394–6.
  7. Stoneham MD. The nasopharyngeal airway. Assessment of position by fiberoptic laryngoscopy. Anesthesia 1993;48:575–80.
  8. Camacho, M., Chang, E.T., Fernandez-Salvador, C., & Capasso, R. Treatment of snoring with a nasopharyngeal airway tube. 2016. http://dx.doi.org/10.1155/2016/3628716
  9. Farzan, Sattar, MD, FACP, FCCP A Concise Handbook of Respiratory Diseases. Prentice Hall 1997. Accessed January 2019.