In a few words 8: The pharyngeal airway
Jeff Kenneally – www.Prehemt.com
Clinical guidelines for managing emergency medical and traumatic problems begin with ‘ensure patent airway’. Patent means the airway ‘pipe’ is open to allow air to move in and out. Not patent typically means the ‘pipe’ is partly or completely blocked or obstructed. A common obstruction is the soft palate, tongue and epiglottis. The latter two are designed to fall back and occlude the glottis during swallowing. They can also do so when unconscious and muscle tone is lost. The soft palate lies between the hard upper airway and the larynx. This is muscular but, when consciousness is lost, this part of the airway also collapses. Between the two problems, upper airway patency is threatened. Two devices that can displace them away from the glottis are the oropharyngeal and nasopharyngeal airway.
The oropharyngeal or guedels airway (OPA) is a curved piece of hollow plastic that follows the line of the tongue from the mouth to the oropharynx. They come in different sizes so must be measured, from angle of jaw to incisor on that side or tragus to corner of the mouth, for each patient. Too small and it pushes into the tongue without moving it forward. Too big and it can injure the soft posterior airway tissue. An OPA cannot be inserted past clenched teeth or trismus. Nor can it remain inserted where there are some airway reflexes and gagging can cause vomiting or problems with intracranial pressure rising. The OPA does not help with other types of airway obstruction such as foreign bodies or vomitus.
Where the OPA cannot be inserted because of biting or residual airway reflexes, there is an alternative. The nasopharyngeal airway is another curved tube that can be inserted through a nostril, run parallel along the base of the nasal cavity, and sit approximately where the OPA normally would. It can get around biting and trismus. It is also much less likely to cause gagging and stimulate airway reflexes if they are slightly intact given how soft the airway is. They are measured like the OPA only from the angle of the jaw to the nostril. It should not be inserted where there is major injury to the nose. It should also be inserted carefully when base of skull injury is suspected.