Part 4: Can we have one without the other?
First to consider is the problem common to both principal types of video laryngoscopes, the standard geometry and hyperangulated blades. If reliance on the camera is needed to operate the device, failure of the camera limits its universal applicability. While there is no evidence on how often camera failure occurs, in my personal experience it is too often to cast out direct laryngoscopy. During the first 5 months of my residency, the GlideScope camera shut off in the middle of two intubation attempts. The results were not pretty. And less than halfway through my second year, the only GlideScope in our department is currently out for repair for the third time during my short career.
It’s not only technical failure of the camera. Blood and emesis can contaminate the camera as well, a particular challenge during emergency and trauma airway management. Also, because a hyperangulated does not align the axes of the airway, any foreign body removal proves to be much more difficult. In a cadaver study comparing the Macintosh direct laryngoscope to the GlideScope, foreign body removal was more successful and faster with DL as compared to the GlideScope, as can be seen in the figure below.
But perhaps a more dramatic example of this is demonstrated in the video here.
As alluded to at the beginning of this series, the debate between VL and DL is in a certain way pointless because standard geometry or Macintosh video laryngoscopes offer the best of both worlds. Obtaining a view of the glottis requires the same technique as direct laryngoscopy, and the device allows direct visualization for tube delivery (and foreign body removal), which I would argue should be our first-line method for intubation given the high numbers required for competency with direct laryngoscopy. Plus this direct view mitigates any risk of camera failure or contamination. If the glottis cannot be visualized directly, the video screen should reveal a higher Cormack-Lehane view and therefore allow for intubation most of the time.2 In contrast, when the camera does not work with hyperangulated video laryngoscopes, intubation is impossible.
With this strategy, your first backup (the camera) is built-in to your first attempt. For the rare circumstance when this method fails, there is always hyperangulated VL to bail you out. And I say rare, because use of a standard geometry VL (with a bougie) achieves a first pass success of 98%.3 If airway management is plan A, B, C, D, etc, then this strategy affords us the most options:
Take Home Points:
- Camera failure and contamination are disadvantages of VL
- With camera failure, hyperangulated VL is useless
- With camera failure, Macintosh or standard geometry VL can still be used as a direct laryngoscope
- Macintosh or standard geometry laryngoscopes are superior to hyperangulated laryngoscopes for foreign body removal
- Macintosh VL allows for direct visualization and the camera affords a higher Cormack-Lehane view as an intrinsic backup
- Je SM, Kim MJ, Chung SP, Chung HS. Comparison of GlideScope(®) versus Macintosh laryngoscope for the removal of a hypopharyngeal foreign body: a randomized cross-over cadaver study. Resuscitation. 2012;83(10):1277-1280. doi:10.1016/j.resuscitation.2012.02.032
- Brown 3rd CA, Bair AE, Pallin DJ, Laurin EG, Walls RM, National Emergency Airway Registry Investigators. Improved glottic exposure with theVideo Macintosh Laryngoscope in adult emergency department tracheal intubations. Ann Emerg Med 2010;56:83–8.
- Driver BE, Prekker ME, Klein LR, Reardon RF, Miner JR, Fagerstrom ET, Cleghorn MR, McGill JW, Cole JB. Effect of Use of a Bougie vs Endotracheal Tube and Stylet on First-Attempt Intubation Success Among Patients With Difficult Airways Undergoing Emergency Intubation: A Randomized Clinical Trial. JAMA. 2018 Jun 5;319(21):2179-2189. doi: 10.1001/jama.2018.6496. PMID: 29800096; PMCID: PMC6134434.