Films and Scans
Before starting efforts at intubating any airway with laryngeal pathology, it must be appreciated by all caring for the patient that rescue ventilation may not work if the epiglottis or larynx is swollen or distorted. This applies to the LMA, King LT, and mask ventilation. If intubation through the nose or mouth doesn’t work, a rapid surgical airway will likely be required. The equipment and personnel to do this should be brought to the bedside if this is happening in the ED. A marking pen is useful to mark the neck should a surgical airway be required. Oral and nasal airways should be ready for mask ventilation if a surgical airway is needed. When mask ventilating a patient with epiglottitis, additional hands should be used to distract the mandible upward, lifting the submental tissue to try to keep the epiglottis off the posterior pharyngeal wall. Supraglottic airways like the LMA and King LT, may push the swollen epiglottis over the laryngeal inlet and cause a complete obstruction. Surgical airways begun on a dead patient end with a dead patient, given that the average time to ventilation is about 100 seconds. If intubation efforts are prolonged, leading to hemodynamic instability or significant hypoxia, it is critical to initiate a surgical airway immediately (ideally before any patient compromise). Assuming anesthesia and surgical personnel are available, and the patient can tolerate the delay, it may be better in some venues to manage these patients in the OR instead of the ED. The following discussion relates to management in the ED.
Flexible fiberoptics are the ideal means to intubate patients with abnormal laryngeal pathology because the patient can maintain a position that maximizes airway dimensions (i.e. patient upright with ear-to-sternal notch alignment; head forward relative to the chest). With proper topicalization and pharmacologic adjuncts (benzodiazepines and ketamine) patient movement and discomfort can be minimized. Small doses of midazolam (2-4 mg) and 10 mg aliquots of ketamine (titrated as required) is usually sufficient. Synthetic opiates such as remifentanyl, and other pharmacologic agents have also been used for fiberoptic intubation, but are rarely readily available in the ED setting. Fiberoptic intubation allows visual inspection of the airway with the patient upright and breathing spontaneously. The nasal approach is much straighter than navigating about the curvature of the oropharynx.
Specific details of nasal intubation technique were covered in a prior issue of EPM; the key steps involve use of a nasal trumpet, and using a specific nasal tube (ideally a soft durometer with a trigger mechanism such as a Mallinkrodt Endotrol or Parker Articulating tracheal tube). If oral intubation using a fiberscope is desired (and it certainly has its advantages in situations when intubation is expected to be prolonged, such as when avoiding the sinusitis that occurs with nasal intubation after 48-72 hours), a specific fiberoptic oral airway is recommended. Options include the Berman intubating airway, the Ovassapian, and the Williams. These devices provide a channel to navigate around the tongue and also allow tongue distraction.
Proper topicalization of the airway and adjunctive medications are necessary to overcome the patient’s protective reflexes preventing tube insertion. Oxymetazoline is ideal to minimize bleeding if the nasal route is chosen. Lidocaine (2% used for injection, or 4% topical solution) can be nebulized, injected through a trans-tracheal puncture, or applied to the airway using disposable atomizers. While lidocaine toxicity and death has occurred with 10% spray (no longer on the market in the USA), a recent study found levels in obese patients undergoing awake fiberoptic intubation were below a toxic range even if 40 cc of 4% was used. It is presumed that much of the solution applied to the airway was swallowed and digested, not absorbed into the bloodstream. In the author’s experience, smaller volumes – 10 cc of 4% or 20 cc of 2% – are usually sufficient.
Direct laryngoscopy or video laryngoscopy can be performed in an upright, leaning forward position, but the stimulation of the instrument against the tongue and the gag reflex make it difficult for most patients to tolerate. Ketamine, which works well in nasal intubation, may trigger masseter spasm, making the oral route difficult. Direct laryngoscopy is especially challenging relative to video laryngoscopy because of the greater force usually required to expose the larynx; devices such as the Glidescope or Series 5 McGrath – those that are hyperangulated – would probably be better tolerated with easier exposure in an upright patient than video laryngoscopes such as the Storz C-Mac or MacGrath Mac which have less curvature. In the patient who has no muscular tone, it may be worthwhile attempting intubation once from above with the patient supine, using a straight blade laryngoscope (to lift the epiglottis directly), or a video laryngoscope, understanding that speed is safety, and that a surgical airway should not be delayed.
Regardless of which route is taken, the key to successfully intubating patients with abnormal laryngeal anatomy is to recognize the epiglottis. It must be seen from above before getting too deep into the laryngeal inlet. It is distinguishable by its horizontal orientation, even if swollen. Conversely, the glottic opening has a vertical orientation, even if the posterior cartilages or false vocal cords are edematous and obscure the true cords.
Remember to maximize efforts at oxygenation throughout any effort at intubating these patients. Patients with infectious processes and agitation will have tachycardia and high metabolic demands, leading to extremely short safe apnea times. Nasal oxygen can be applied to the contralateral nare, or the mouth when using a nasal approach to intubation, or applied to both nares if going through the mouth. Nasal oxygen is usually much better tolerated than placing a mask over an air-hungry patient’s face. There are specialized masks and swivel adapters for mask ventilating patients when using a fiberscope, but these are rarely going to be present in the ED. Heli-ox may be especially useful in compromised airways during intubation efforts; compared to standard oxygen it has greater tendency to laminar flow, and less resistance in turbulent flow.
A final pitfall in managing the airways of patients with epiglottis or other laryngeal pathology relates to post-intubation management. Once the tube is placed in the trachea, and confirmed through breath sounds audible through the tube (in the spontaneously breathing patient) great care should be taken to avoid unintended extubation. Patients need to have their hands restrained, and pharmacologic adjuncts (sedatives, muscle relaxants) should be used to prevent patient movement and coughing. Equipment for a surgical airway should be kept at the bedside, even after intubation, should unexpected extubation occur.