The "Guedel" style oropharyngeal airway

Also known as the "Guedel" airway, the oropharyngeal airway tube is a simple adjunct which bypasses the oropharynx and allows air (oxygen, sedating gas, etc) to bypass the tongue and upper pharynx. The use of this device is reserved for the incompletely conscious, as its insertion into the face of an alert person is usually greeted with violent confrontation. As such, one can usefully gauge the need for intubation by the degree to which this thing is tolerated (i.e. if it is well tolerated, then by definition the patient is not protecting their airway).

Anatomy of the oropharyngeal Guedel-style airway

Details of function

Essentially, this rigid tube offers a bite-resistant passage for air from the lips to the posterior pharynx.

The curved portion rests between the posterior pharyngeal wall and the tongue, keeping the epiglottis off the posterior pharyngeal wall (where it would normally be forced into by the flaccid collapse of the tongue).

Indications for use

• To ensure airway patency:
  • Unconscious patient with loss of upper airway muscle tone
  • Unconscious patient with difficult bag/mask seal
  • Intubated patient, in whom the oropharyngeal airway acts as a bite block, preventing the kinking of the softer endotracheal tube
• To improve airway hygiene:
  • Suctioning a patient with poor secretion clearance

Contraindications for use

• Awake patient: An awake patient will not tolerate this airway, as it will stimulate their gag reflex.
• Severe coagulopathy: this device, although possessing rounded edges, is still made of very hard plastic and it can still cause lacerations to the oral mucosa. If you have no platelets, you may end up with a lung full of blood from some sort of little posterior pharyngeal bleeder before anybody notices.

Methods of use/insertion

• The tube is sized by placing it vertically, with the flange in the middle of the lips and the tip emerging at the angle of the mandible.
• In adults it is inserted into the mouth upside-down, and rotated into the normal position once it is inserted about half way.
• Lubricant may be useful if the mouth is excessively dry.

Safety features

• The airways are colour coded to help recognise the sizes; the length of the tube is marked on the flange with a number (eg. "10" implies that the tube is 10cm long)
• The flange limits the depth of insertion - so you cant accidentally lose the tube in somebody's airway
• The reinforced bite block prevents occlusion of the airway by clenching of the teeth
• The rigid construction is kink-resistant (although, if you really want, you can still kink it)
• Available as a sterile product for single use; though most of the time the packaging is non-sterile (it tends to be cheaper that way, and one might make the argument that the oropharynx is not a sterile field anyway).

Complications of use

• Gagging/vomiting, aspiration
• Damage to oral mucosa, and bleeding
• Damage to teeth, particularly if the patient bites down forcibly on the bite block.
• Occlusion of the glottis by an inappropriately sized larger-than-needed tube
• Failure of airflow due to an inappropriately small tube pushing the tongue into the posterior pharynx, or an inappropriately large tube pushing the epiglottis down into the trachea.

Airway obstruction may result even from the use of an appropriately sized airway. Marsh et al (1991) reported on a case series of 22 patients in whom lateral neck Xrays were performed after Guedel insertion; in several the airway was either obstructed by the epiglottis or slipped into the vallecula. Weirdly, a radiologically malpositioned airway was not always associated with any clinical evidence of obstruction.

Apocrypha

This airway was actually first developed by Arthur Ernest Guedel (1883–1956). The very same Guedel also proposed a system to classify the stages of anesthesia, which has been retained in classical anaesthetic training in spite of the fact that most modern agents will drop you within seconds, and nowadays the stages all blend into one.

But I digress. The early oropharyngeal airways were already flanged, but in 1933 they were made of hard metal, which (very likely) chipped and loosened many rotten post-Depression era teeth. Guedel's great advance was making them from rubber, which was a massive improvement over the cruel-looking all-metal Connell airway.