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Apparent Difficult Airway - Anatomy, Injury, Physical/Mechanical Problems


The difficult airway may be due to anatomic reasons: large tongue, short neck, limited extension, etc. Facial or neck trauma may distort the airway and blood may make visualization difficult though this may not be apparent from the external appearance of the patient. There may also be upper airway injury or physical/mechanical hindrance, i.e. a halo or jaws wired shut.

Techniques:

Awake direct laryngoscopy
Awake fiberoptic
Surgical airway

If there appears to be any reason to think that controlling the airway will be difficult it is imperative to not take away the patient's ability to spontaneously ventilate [reference8]. If a patient's ability to spontaneously ventilate is removed and if the clinician cannot intubate there may also be difficulty ventilating, this is an acute emergency. A patient that can no longer oxygenate or ventilate and some other form of airway must be rapidly obtained.

If an awake techniques is used, the patient will require some form of topical anesthetia. The patient may require minimal sedation, especially if uncooperative, remembering that with sedation there may be respiratory depression, circulatory depression and disinhibition.

It may be prudent to immediately go to a surgical airway under local. This allows the patient to continue to maintain their own airway and the clinician to gain control of the airway. This may be the only option if other methods have been exhausted.

The apparent difficult airway is frustrating in that it turns a potentially easy airway into a potentially difficult one. It is mportant to remember that problems with airway management may often occur and that the proper personnel and equipment should be available, in the event a surgical airway is needed [reference 9]. A surgeon can be used to apply cricoid pressure [reference 11].

Known Difficult Airway


In this situation, the difficult airway is known and that it limits options.

Techniques:

Awake direct laryngoscopy
Awake fiberoptic
Surgical airway

Spontaneous respiration should be maintained [reference 8] in the event the airway cannot be quickly secured. Adequate topicalization is essential along with minimal sedation. In the difficult airway, the airway can easily be lost, therefore the necessary equipment/personnel need to be available in the event a surgical airway is needed.

The difficult airway that needs to be emergently intubated is a very tenuous situation. It is helpful to have experienced hands available for assistance in the event they are needed [reference 9].

Unstable Cervical Spine

Halo fixation


Cervical spine (C-spine) injuries occur in 1.5%-3.0% of all major trauma cases [reference 10].When a patient with an unstable C-spine needs to be intubated, either emergently or prior to an operation, it is important to protect the C-spine. Care must be taken not to cause any excessive movement of the neck which might cause neurologic deficit. Patients who already have a deficit, eg are quadriplegic on admission, should be treated in the same manner as woresening of the injry may occur. Neurologic deficit may be secondary to edema and may improve with time.

No single technique has proved to be better and that it has been suggested that any technique that the clinician is skilled at can be used successfully. However, it has been shown that the basic airway maneuvers of the chin lift and jaw thrust have been shown to cause problems secondary to movement and should be avoided.

Techniques:

Awake fiberoptic
Blind nasal
Rapid Sequence Intubation with in-line stabilization

Awake fiberoptic is good choice as long as neck motion can be kept to a minimum. However the airway can be full of secretions or blood and the patient may not be cooperative, which can make this technique impossible.

Blind nasal intubation can be used. Minimal neck movement maintenance of spontaneous ventilation are benefits of this choice. Blind nasal intubation can be performed in a patient who is not cooperative. It is contraindicated if there is basal skull fracture or if there is a fear of disruption of the ethmoid plate; case reports have described the ETT entering the brain substance. The major risks of the blind nasal are epistaxis, vomiting and regurgitation. If any of these do occur they may make awake fiberoptic intubation difficult.

Rapid Sequence Intubation (RSI) can be accomplished with the aid of manual in-line stabilization of the head and neck. In-line stabilization is performed by having the patient lie supine with the head in the neutral position; an assistant grasps the mastoid processes, the front of the semi-rigid collar is removed; the collar can impede mouth opening, does not contribute significantly to neck stabilization during laryngoscopy, and will be an obstruction if a surgical airway is required. Manual in-line stabilization reduces neck movement during intubation, but care is taken to avoid excessive axial traction which may cause distraction and subluxation. This technique requires a minimum of three, but ideally four, individuals: the first to pre-oxygenate and intubate: the second to apply cricoid pressure; the third to maintain manual in-line stabilization of the head and neck; and the fourth to give intravenous drugs and assist. A gum elastic bougie should be kept at hand and is used immediately if the view is obscured and/or intubation proves difficult. The posterior portion of the semi-rigid collar, which is left in place during the entire maneuver, helps to prevent flexion of the cervical spine during the application of firm cricoid pressure [reference 11].

The best technique to intubate a patient with an unstable C-spine has not been decided . The procedure chosen should be the one that the practionar is most familiar. It has been suggested that in the hands of an experience practioner, the procedure of tracheal intubation in a patient with a C-spine injury is a "low-risk intervention."


Combative Patient

Techniques:

Rapid sequence induction
Awake techniques

The combative patient may be extremely difficult to intubate awake. The patient who is combative and seriously injured can be paralyzed and intubated to facilitate physical examination of the patient. Care should be taken to stabilize the neck if cervical injury is a possibility. Consideration should be given to the patient's overall condition and any contraindications to paralysis should be sought, eg potential difficult airway. The patient will not cooperate with any awake techniques, therefore, the option is rapid sequence intubation.

Emergency paralysis with intubation can be an effective method of restraint for the uncooperative, combative, serioulsy injured patient. However, given the risks of paralysis and intubation, this should be avoided unless absolutely required.
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