Article review: Glidescope success in difficult airway simulation
This education article Sim Healthcare is a head-to-head comparison between video laryngoscopy (VL) versus direct laryngoscopy (DL) in a difficult airway simulation model. In this prospective, convenience sample of EM attendings and residents who were all novice operators of VL, the subjects were asked intubate 3 types of mannequin scenarios using a Macintosh curve laryngoscope for DL and a Glidescope for VL.
- Normal airway
- Decreased neck mobility
- Tongue edema
The subjects were timed for the following critical actions:
- Time to visualization of vocal cords
- Time to endotracheal tube through the vocal cords
Other outcome measures included:
- Grading of glottic view at time of intubation using the Cormack Lehane classification (Grade I: most of glottis seen; Grade II: only posterior portion of glottis can be seen; Grade III: only epiglottis may be seen (none of glottis seen); Grade IV: neither epiglottis nor glottis can be seen
- Intubation success
- Time to intubation for a mannequin with a NORMAL AIRWAY and DECREASED NECK MOBILITY actually was statistically faster with DL using a Macintosh blade by 9.4 and 16.1 seconds, respectively.
- Time to visualization of vocal cords for mannequin with TONGUE EDEMA was much faster for VL compared to DL by 89 seconds.
- The success rate of intubation for a mannequin with TONGUE edema was higher for VL compared to DL (83% vs 23%).
- In all scenarios, VL allowed for a better Cormack-Lehane view of the glottic opening compared to DL.
So why didn’t the consistently better Cormack-Lehane view of the glottic opening with VL correlate with a faster intubation time for mannequins with a normal airway and decreased neck mobility? Why was DL faster in these cases?
Consistent with my experience and the literature, it takes some practice and learning to bend the endotracheal tube’s stylet into a sharp enough 60-degree angle. In our ED, we use stylets specifically built for the Glidescope. These stylets are more rigid than the typical stylet and are bent at a sharp angle to allow the endotracheal tube to reach a more anterior glottic opening, if needed.
This study was impressive in that novice VL users only needed a simple 10-minute training session to demonstrate a significant difference in intubation success rate for difficult airway scenarios, such as tongue edema. There are obvious study limitations (eg. mannequins may not simulate real-life difficult-airway scenarios, the order of scenarios was not randomized per subject, and there were no control subjects).
Still, I’m a huge fan of video laryngoscopy. Even if it performed the same as DL, it adds tremendous value to academic ED’s because faculty can now see what is going on and give real-time feedback to residents performing intubations.
Does anyone use video laryngoscopy? Any words of advice or thoughts? Please comment.
Narang AT, Oldeg PF, Medzon R, et al. Comparison of intubation success of video laryngoscopy versus direct laryngoscopy in the difficult airway using high-fidelity simulation. Sim Healthcare 2009; 4:160–5.
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