Direct Laryngoscopy

Head Elevation

In emergency airway management operators should be ready to respond to poor laryngeal view within their first laryngoscopy and intubation attempt. There should be a specific planned approached to find the epiglottis and optimize blade tip position.  In addition to bimanual laryngoscopy (and making sure the curved tip is driven fully into the vallecula), another applicable technique for improving an epiglottis-only view is to dynamically lift the patient’s head higher.  This technique, labeled by Dr. Levitan as Head Elevated Laryngoscopy Positioning, a.k.a. HELP, was first described by Richard Johnston in 1909, and then later adopted by Chevalier Jackson. Head elevation permits greater jaw distraction because of its mechanically favorable effect on mouth opening.  It enlarges the area beneath the base of the tongue and epiglottis improving visualization.  According to Jackson, exaggerated head elevation (what he called the Raised Extended Position) also better aligned the blade axis with the axis of the upper trachea and larynx.  Jackson referred to normal recumbancy as the "death position" because it did not open the airway. Image below is from Jackson's 1922 textbook, Bronchoscopy and Esophagoscopy. A manual of peroral endoscopy and laryngeal surgery.

Head elevation was critical to Jackson: “Overextension of the patient’s neck is a frequent cause of difficulty. If the head is held high enough extension is not necessary, and the less the extension the less muscular tension there is in the anterior cervical muscles.”

Schmitt has shown in a large series of 1500 patients, in whom 21 were epiglottis-only views, that combining external pressure on the larynx with maximal head elevation provided a view of the larynx in 19 of the 21 difficult airways:

Schmitt HJ, Mang H., Head and neck elevation beyond the sniffing position improves laryngeal view in cases of difficult direct laryngoscopy. J Clin Anesth. 2002; 14: 335-8.

Using force measurement, Hochman, Zeitels, and Heaton demonstrated that increasing neck flexion (head elevation) maximized laryngeal exposure with the least amount of force:

Hochman II, Zeitels SM, Heaton JT. Analysis of the forces and position required for direct laryngoscopic exposure of the anterior vocal folds. Ann Otol Rhinol Laryngol. 1999; 108: 715-24.

Levitan combined an angle finder and continuous videography from the laryngoscopists’s perspective (Airway Cam imaging) to correlate increasing head elevation with improved layngeal exposure in cadavers:

Levitan RM, Mechem CC, Ochroch EA, Shofer FS, Hollander JE.  Head-elevated laryngoscopy position: improving laryngeal exposure during laryngoscopy by increasing head elevation. Ann Emerg Med. 2003 ; 41: 322-30.

Lee, Kang, and Kim demonstrated that head elevation significantly improved laryngeal view using angle finders and endoscopic imaging down the laryngoscope.:
Lee BJ, Kang JM, Kim DO.  Laryngeal exposure during laryngoscopy is better in the 25 degrees back-up position than in the supine position. Br J Anaesth. 2007; 99: 581-6.

Rao and colleagues validated head elevated positioning in the morbidly obese:
Rao SL, Kunselman AR, Schuler HG, DesHarnais S.  Laryngoscopy and tracheal intubation in the head-elevated position in obese patients: a randomized, controlled, equivalence trial. Anesth Analg. 2008; 107: 1912-8.

An operator can perform head elevation by using their right hand to lift the patient’s occiput. Alternatively, some practitioners have used their abdomen (works especially well when pregnant according to some sources) to lean forward and prop up and elevate the patient’s head.  Alternatively, an assistant can help by using two hands to lift the head from the patient’s side. 

Dynamic head elevation is contraindicated in situations of cervical spine precautions.

In the morbidly obese dynamic lifting is not feasible given the weight involved.  A large ramp is needed not only under the occiput, but also the upper shoulders, and even down to the mid back in order to provide proper positioning.  Rao et. al., have shown that in the operating room this positioning can also be achieved with an articulating table.  Ear-to-sternal notch positioning, i.e., pre-positioning the patient beforehand, is required in the morbidly obese–before efforts at mask ventilation and intubation.

In order to dynamically lift the head during laryngoscopy, the patient’s stretcher height must be kept low enough to permit head elevation, and yet still provide a perspective for the operator to look down the mouth with the patient’s face plane parallel to the ceiling.  For some operators, especially when dealing with larger patients (and depending upon stretcher positioning), this may require a stool for the operator to be at proper height.