eTable 1. Search strategies for database search.

Database (date of first search)	Search strategy
MEDLINE (24 May 2017)	(Video[TiAb] OR Video-laryngoscopy[TiAb] OR videolaryngoscopy[TiAb] OR videolaryngoscope[TiAb] OR ‧videolaryngoscopies[TiAb] OR videolaryngoscopes[TiAb] OR video laryngoscopy[TiAb] OR ‧video-laryngoscope[TiAb] OR video laryngoscope[TiAb] OR video-laryngoscopes[TiAb] OR ‧video ‧laryngoscopes[TiAb] OR video-laryngoscopies[TiAb] OR video laryngoscopies[TiAb] OR GlideScope[TiAb] OR ‧Verathon[TiAb] OR C-MAC[TiAb] OR CMAC[TiAb] OR AWS-S200[TiAb] OR McGrath[TiAb] OR STORZ[TiAb] OR “McGrath MAC”[TiAb] OR MAC[TiAb] OR EMS[TiAb] OR “Infinium ClearVue”[TiAb] OR UESCOPE[TiAb] OR ‧“UE Medical”[TiAb] OR ‧IntuBrite[TiAB] OR Marshall[TiAb] OR “VLS 6630”[TiAB] OR MEDAN[TiAb] OR ‧APA[TiAb] OR Coopdech[TiAb] OR VLP-100[TiAb] OR Venner Medical[TiAb] OR Kanlife[TiAb] OR ‧PENTAX[TiAb] OR ‧Novamed[TiAb] OR Pentax-AWS[TiAb] OR “King Vision”[TiAb] OR CoPilot[TiAb] OR ‧Rusch[TiAb] OR Airtraq[TiAb] OR “Truview PCD”[TiAb]) AND (laryngoscop*[TiAb] OR ‧“laryngoscopy”[MeSh Terms] OR direct laryngoscopy[TiAb] OR direct ‧laryngoscope[TiAb] OR ‧direct ‧laryngoscopies[TiAb] OR direct laryngoscopes[TiAb] OR macintosh[TiAb] OR ‧standard ‧laryngoscope[TiAb] OR standard laryngoscopes[TiAb] OR standard laryngoscopy[TiAb] OR ‧conventional ‧laryngoscopy[TiAb] OR conventional laryngoscope[TiAb] OR conventional laryngoscopes[TiAb]) AND (randomized controlled trial[Publication Type] OR controlled clinical trial[Publication Type] OR randomized[TiAb] OR ‧randomised[TiAb] OR placebo[TiAb] OR “drug therapy”[Subheading] OR randomly[TiAb] OR trial[TiAb] OR groups[TiAb] NOT (“animals”[MeSh terms] NOT “humans”[MeSh terms]))
Embase (24 May 2017)	(‚video‘:ti,ab OR ‚video-laryngoscopy‘:ti,ab OR ‚videolaryngoscopy‘:ti,ab OR ‚videolaryngoscope‘:ti,ab OR ‧‚videolaryngoscopies‘:ti,ab OR ‚videolaryngoscopes‘:ti,ab OR ‚video laryngoscopy‘:ti,ab OR ‧‚video-laryngoscope‘:ti,ab OR ‚video laryngoscope‘:ti,ab OR ‚video-laryngoscopes‘:ti,ab OR ‧‚video ‧laryngoscopes‘:ti,ab OR ‚video-laryngoscopies‘:ti,ab OR ‚video laryngoscopies‘:ti,ab OR ‚glidescope‘:ti,ab OR ‧‚verathon‘:ti,ab OR ‚c-mac‘:ti,ab OR ‚cmac‘:ti,ab OR ‚aws-s200‘:ti,ab OR ‚mcgrath‘:ti,ab OR ‚storz‘:ti,ab OR ‚mcgrath mac‘:ti,ab OR ‚mac‘:ti,ab OR ‚ems‘:ti,ab OR ‚infinium clearvue‘:ti,ab OR ‚uescope‘:ti,ab OR ‚ue ‧medical‘:ti,ab OR ‧‚intubrite‘:ti,ab OR ‚marshall‘:ti,ab OR ‚vls 6630‘:ti,ab OR ‚medan‘:ti,ab OR ‚apa‘:ti,ab OR ‧‚coopdech‘:ti,ab OR ‚vlp-100‘:ti,ab OR ‚venner medical‘:ti,ab OR ‚kanlife‘:ti,ab OR ‚pentax‘:ti,ab OR ‧‚novamed‘:ti,ab OR ‚pentax-aws‘:ti,ab OR ‚king vision‘:ti,ab OR ‚copilot‘:ti,ab OR ‚rusch‘:ti,ab OR ‚airtraq‘:ti,ab OR ‚truview pcd‘:ti,ab) AND ‧(‚laryngoscop*‘:ti,ab OR ‚laryngoscopy‘/de OR ‚direct laryngoscopy‘:ti,ab OR ‧‚direct ‧laryngoscope‘:ti,ab OR ‚direct ‧laryngoscopies‘:ti,ab OR ‚direct laryngoscopes‘:ti,ab OR ‚macintosh‘:ti,ab OR ‚standard laryngoscope‘:ti,ab OR ‧‚standard laryngoscopes‘:ti,ab OR ‚standard laryngoscopy‘:ti,ab OR ‧‚conventional laryngoscopy‘:ti,ab OR ‧‚conventional laryngoscope‘:ti,ab OR ‚conventional laryngoscopes‘:ti,ab) AND (‚crossover procedure‘:de OR ‧‚double-blind procedure‘:de OR ‚randomized controlled trial‘:de OR ‧‚single-blind ‧procedure‘:de OR random*:de,ab,ti OR factorial*:de,ab,ti OR crossover*:de,ab,ti OR (cross NEXT/1 over*):de,ab,ti OR placebo*:de,ab,ti OR (doubl* ‧NEAR/1 blind*):de,ab,ti OR (singl* ‧NEAR/1 blind*):de,ab,ti OR assign*:de,ab,ti OR allocat*:de,ab,ti OR volunteer*:de,ab,ti)
CENTRAL (24 May 2017)	#1 MeSH descriptor: [Laryngoscopy] #2 “video”:ti,ab #3 Video-laryngoscopy:ti,ab #4 „videolaryngoscopy“:ti,ab #5 videolaryngoscope:ti,ab #6 videolaryngoscopies:ti,ab #7 videolaryngoscopes:ti,ab #8 video laryngoscopy:ti,ab #9 video-laryngoscope:ti,ab #10 video laryngoscope:ti,ab #11 video-laryngoscopes:ti,ab #12 video laryngoscopes:ti,ab #13 video-laryngoscopies:ti,ab #14 video laryngoscopies:ti,ab #15 GlideScope:ti,ab #16 Verathon:ti,ab #17 C-MAC:ti,ab #18 CMAC:ti,ab #19 AWS-S200:ti,ab #20 McGrath:ti,ab #21 STORZ:ti,ab #22 McGrath MAC:ti,ab #23 “MAC EMS”:ti,ab #24 UE Medical:ti,ab #47 (#3 or #39 or #40 or #41 or #42 or #43 or #44 or #45 or #46) and (#1 or #2 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11 or #12 or #13 or #14 or #15 or #16 or #17 or #18 or #19 or #20 or #21 or #22 or #23 or #24 or #25 or #26 or #27 or #28 or #29 or #30 or #31 or #32 or #33 or #34 or #35 or #36 or #37 or #38)