Recognizing different degrees of airway obstruction and restoring or maintaining airway patency is an integral part of airway management. This skillset is essential for the provision of safe general anesthesia, particularly during the induction and emergence phase when (a degree of) airway obstruction is a common occurence.
Level of obstruction
Airway obstructions can occur in several anatomical areas:
Causes of airway obstruction
The most common cause of airway obstruction in the anesthesia setting is iatrogenic, i.e. occurs with induction of general anesthesia/ sedation, when a reduced level of consciousness and loss of pharyngeal muscle tone leads to the back of the tongue falling backwards against the posterior pharyngeal wall in the patient positioned supine. Other conditions causing a reduced level of consciousness (intoxication, stroke, head injury, ...) can lead to airway obstruction for the same reason.
(Partial) upper airway obstruction due to the same mechanism can occur during sleep causing snoring and as a consequence of obstructive sleep apnea.
The potential types of obstacles to gas flow through the airway are blood, pus, secretions, edema and hematoma, either within the airway or external to the airway but compressing it, tumor or other tissue, a foreign body, regurgitated material or the vocal chords in cases of paralysis.
If there is any question of airway compromise, start giving oxygen while assessing the patient further!
Level of consciousness
Assess patient's ability to verbalize and voice quality
A patient who is verbalizing Responding level of consciousness, quality of voice, verbalizing requires reasonable patency of airway, also assesses degree of potential dyspnea, can talk in full sentences
Assess respiratory rate and pattern
Dyspnea, Look for tachypnea, respiratory rate, accessory muscle use
Apart from assessing the rate of respiration, also look for an abnormal respiratory pattern, inparticular accessory respiratory muscle use. This might herald impending respiratory failure due to muscular exhaustion.
Expose the patient's chest
Assess gas exchange
Mainly look for signs of hypoxia cyanosis. Hypercarbia is difficult to diagnosed clinically, CO2 narcosis. Pulse oximetry is now readily available in most clinical settings.
Listen for stridor, indicating obstruction at laryngeal level or snoring, indicating obstruction at the nasopharyngeal or oropharyngeal level.
Expose the patient's chest and inspect the chest wall for signs of airway obstruction, namely tracheal tugging and a 'see-saw' breathing pattern.
While clinical assessment is the mainstay of diagnosing airway obstruction, some investigation can provide useful additional information. But always make sure not to delay urgent and potentially life-saving interventions by performing test, unless they might lead you to change your airway management approach.
As a bedside test, nasal endoscopy, which is relatively non-invasive, is usually well-tolerated after topical local anesthesia application with a nasal atomizer.
Imaging by x-ray or more so by CT and MRI can be particularyl helpful in subglottic airway obstructions which are not easy to assess by clinical examination only. Again, balance the need for a potentially lengthy scanning procedure with the urgency of managing an acute airway compromise.