A Skeptical Look at a VL vs. DL Meta-analysis

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This meta-analysis of direct vs video laryngoscopy showed no improvement in first-pass success with VL over DL, but it excluded patients at risk for a difficult airway.  So view this with a healthy skepticism.

Why does this matter?
More and more, we have been moving toward VL as first line for emergency intubation, but study results have been mixed.  Observational studies have been favorable for VL.  RCTs have been less so.  The authors chose only RCTs for this meta-analysis.

Wish we could exclude patients with potentially difficult airways too
The authors found 12 RCTs that compared VL to DL, with a primary outcome of first-pass success.  They concluded that VL was worse in the prehospital environment, which we covered on JF.  In the hospital setting, there was no difference in VL vs DL regarding first-pass success.  But there were multiple problems with this study.  One was that most of the RCTs excluded patients with known/suspected difficult airway, hypoxemia, or need for cervical immobilization.  Also, in 7 of 12 studies, they did not consistently use neuromuscular blocking agents (NMBA).  Devices were all over the map: GlideScope, McGrath, Airtraq, Airway Scope, and C-MAC.  Six included the GlideScope, which has a hyperacute angle and is tricky to use, especially for a novice.  Speaking of novice, 5 of 12 studies were with inexperienced intubators who have lower first-pass success with any device.  Jeremy Greenberg, EM/CC in Colorado noted, "the big question is not whether first attempt success is more common in VL vs DL but rather which is superior in the difficult airway?  Since we have no ability whatsoever to predict the difficult airway in the vast majority of airway cases, I fervently believe we should assume them all to be difficult and go with VL."  Given that the subgroup analyses of this study found that VL led to an increased overall intubation success rate and a decreased esophageal intubation rate with a better Cormack and Lehane grade view, VL may be the better choice for the unexpectedly difficult airway.  This study raises more questions than it answers.  Don't abandon VL on the basis of this paper.

Source
Video laryngoscopy does not improve the intubation outcomes in emergency and critical patients - a systematic review and meta-analysis of randomized controlled trials.  Crit Care. 2017 Nov 24;21(1):288. doi: 10.1186/s13054-017-1885-9.

Peer reviewed by Thomas Davis, MD.

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