Videolaryngoscopy versus direct laryngoscopy for adults undergoing tracheal intubation

Jan Hansel; Andrew M Rogers; Sharon R Lewis; Tim M Cook; Andrew F Smith

doi:10.1002/14651858.CD011136.pub3

La vidéolaryngoscopie par rapport à la laryngoscopie directe dans l’intubation trachéale de l’adulte

Appendices

Appendix 1. Videolaryngoscope classification

Device name	Manufacturer	Studies
Macintosh‐style
C‐MAC	Karl Storz SE & Co. KG, Tuttlingen, Germany	Aggarwal 2019; Akbar 2015; Altun 2018; Ander 2017; Aziz 2012; Bhat 2015; Blajic 2019; Caparlar 2019; Cattano 2013; Cavus 2011; Cengiz 2019; Chandrashekaraiah 2017; Dey 2020; Driver 2016; Goksu 2016; Gupta 2013; Hostic 2016; Kapadia 2021; Kucukosman 2020; Maassen 2012; Macke 2020; Marsaban 2017; McElwain 2011; Ninan 2016; Rabbani 2020; Rajasekhar 2020; Sarkilar 2015; Serocki 2010; Sulser 2016; Teoh 2010
McGrath MAC	Medtronic plc, Dublin, Ireland	Altaiee 2020; Altun 2018; Anandraja 2021; Bakshi 2019; Cakir 2020; Colak 2019; Foulds 2016a; Frohlich 2011; Ing 2017; Janz 2016; Kaur 2020; Kido 2015; Kreutziger 2019; Kriege 2020; Lascarrou 2017; Loughnan 2019; Peck 2009; Ruetzler 2020; Shimazaki 2018; Shippey 2013; Thion 2018; Toker 2019; Verma 2020; Wallace 2015; Yoo 2018
X‐lite	Rüsch, Karl Storz Production	Bensghir 2010; Bensghir 2013; Marrel 2007
V‐MAC	Karl Storz SE & Co. KG, Tuttlingen, Germany	Jungbauer 2009; Lee 2012; Yumul 2016
CEL‐100	Connell energy Technology Co. Ltd, Shanghai, China	Lin 2012
GlideScope Mac	Verathon Inc, WA, USA	No studies
AP Advance Mac	Venner Medical, Singapore, Singapore	No studies
Hyperangulated
GlideScope	Verathon Inc, WA, USA	Abdelgalel 2018; Ahmad 2015; Ahmadi 2015; Akbarzadeh 2017; Al‐Ghamdi 2016; Amini 2015; Andersen 2011; Aqil 2016; Aqil 2017; Arslan 2017; Bilehjani 2009; Carassiti 2013; Choi 2011; Cordovani 2019; Dashti 2014; Dostalova 2019; El‐Tahan 2017b; Griesdale 2012a; Gunes 2020; Hsu 2012; Hu 2017; Huang 2020; Inangil 2018; Ithnin 2009; Jafra 2018; Kill 2013; Kim 2016; Lee 2012; Lim 2005; Loughnan 2019; Malik 2008; Malik 2009b; Masoumifar 2020; Misirlioglu 2016; Najafi 2014; Nakayama 2010; Nandakumar 2018; Parasa 2016; Pournajafian 2014; Rewari 2017; Risse 2020; Robitaille 2008; Rovsing 2010; Russell 2012; Russell 2013; Sandhu 2014; Sanguanwit 2021; Sbeghen 2021; Serocki 2010; Serocki 2013; Siddiqui 2009; Silverberg 2015; Sun 2005; Teoh 2010; Trimmel 2016; Tsan 2020; Turkstra 2005; Wasinwong 2017; Wei 2016; Xue 2007; Yeatts 2013; Yousef 2012; Yumul 2016
McGrath Series 5	Medtronic plc, Dublin, Ireland	Arici 2014; Bakshi 2015; Foulds 2016a; Golboyu 2016; Ilyas 2014; Karaman 2016; Laosuwan 2015; Lee 2012; Postaci 2015; Sargin 2016; Taylor 2013; Tempe 2016; Walker 2009; Yao 2015; Yumul 2016
C‐MAC D‐BLADE	Karl Storz SE & Co. KG, Tuttlingen, Germany	Agrawal 2020; Buhari 2016; Echeverri 2020; Hostic 2016; Huang 2020; Paik 2020; Pappu 2020; Pazur 2016; Serocki 2013; Shah 2016; Tosh 2018
King Vision (without channel)	Ambu A/S, Copenhagen, Denmark	Avula 2019; Koennecke 2014
Truview PCD/EVO	Truphatek International Limited, Netanya, Israel	Arora 2013; Bag 2014; Bakshi 2015; Barak 2007; Colak 2015; Inal 2016; Kaur 2020; Kurnaz 2016; Malik 2008; Pappu 2020; Tempe 2016
UEScope	Taizhou Hanchuang Medical Apparatus Technology Co Ltd, Taizhou, China	Abdelgawad 2015; Chen 2019; Gao 2018
AP Advance	Venner Medical, Singapore, Singapore	Kleine‐Brueggeney 2017; Koennecke 2014
McGrath Series 3	Medtronic plc, Dublin, Ireland	Liu 2016
Tosight	Shanghai Jingshen Electronic Technology, China	Liu 2019
Airtraq (without channel)	Prodol, Vizcaya, Spain	Koennecke 2014
Channelled
Airtraq	Prodol, Vizcaya, Spain	Abdallah 2019; Abdelgalel 2018; Acarel 2018; Al‐Ghamdi 2016; Amor 2013; Bensghir 2013; Bhandari 2013; Castillo‐Monzon 2017; Chalkeidis 2010; Colak 2015; Das 2016; El‐Tahan 2017b; Erden 2010; Erturk 2015; Ferrando 2011; Gandhi 2019; Gavrilovska‐Brzanov 2015; Hamp 2015; Hindman 2014; Hirabayashi 2008; Hosalli 2017; Kleine‐Brueggeney 2017; Koh 2010; Maharaj 2006; Maharaj 2007; Maharaj 2008; Mahmood 2015; Marco 2011; Mathew 2018; McElwain 2011; Ndoko 2008; Park 2010; Rabbani 2020; Ranieri 2012; Sansone 2012; Saracoglu 2014; Shukla 2017; Tolon 2012; Trimmel 2011; Turkstra 2009; Varsha 2019; Vijayakumar 2016; Wasem 2013; Yallapragada 2016; Zhao 2014
Pentax AirwayScope (AWS)	Nihon Kohden Corporation, Tokyo, Japan	Abdallah 2011; Aoi 2010; Arima 2014; Cha 2009; Enomoto 2008; Hirabayashi 2009; Kanchi 2011; Kim 2013; Kim 2018; Komatsu 2010; Lee 2013; Malik 2008; Malik 2009a; Malik 2009b; Maruyama 2008a; Maruyama 2008b; Nakayama 2010; Nishikawa 2009; Suzuki 2008; Takenaka 2011; Teoh 2010; Woo 2012
King Vision	Ambu A/S, Copenhagen, Denmark	Aleksandrowicz 2018; Al‐Ghamdi 2016; Ali 2017; Barman 2017; Blajic 2019; Dharanindra 2020; El‐Tahan 2017a; El‐Tahan 2017b; Erdivanli 2018; Gupta 2020; Kleine‐Brueggeney 2017; Kumar 2019; Lopez 2017; Reena 2019

Notes: we excluded the Bullard videolaryngoscope from our review as it is no longer used in regular clinical practice.

Appendix 2. Search strategies

MEDLINE ALL (OvidSP)

videolaryngoscop*.mp.
((video* or indirect) adj5 laryngoscop*).mp.
hyperangulat*.mp.
(Airtraq or Pentax or King Vision or Airway Scope or Vividtrac or Res‐Q‐Scope or Storz or McGrath or Glidescope or ClearVue or Truview or Bullard or CoPilot or UE Scope or UEScope or i‐view or C‐MAC or Intubrite or Anatech or Coopdech or Venner).mp.
1 or 2 or 3 or 4
((randomized controlled trial or controlled clinical trial).pt. or randomi?ed.ab. or placebo.ab. or drug therapy.fs. or randomly.ab. or trial.ab. or groups.ab.) not (exp animals/ not humans.sh.)
5 and 6
limit 7 to dt=20150101‐20210227

Embase (OvidSP)

videolaryngoscop*.mp.
((video* or indirect) adj5 laryngoscop*).mp.
hyperangulat*.mp.
(Airtraq or Pentax or King Vision or Airway Scope or Vividtrac or Res‐Q‐Scope or Storz or McGrath or Glidescope or ClearVue or Truview or Bullard or CoPilot or UE Scope or UEScope or i‐view or C‐MAC or Intubrite or Anatech or Coopdech or Venner).mp.
1 or 2 or 3 or 4
(randomized controlled trial/ or randomization/ or placebo/ or crossover procedure/ or double blind procedure/ or single blind procedure/ or (crossover* or cross over*).ti,ab. or ((singl* or doubl* or trebl* or tripl*) adj (blind* or mask*)).ti,ab. or (controlled adj3 (study or design or trial)).ti,ab. or (placebo* or allocat* or trial* or random* or groups).ti,ab.) not ((exp animal/ or animal.hw. or nonhuman/) not (exp human/ or human cell/ or (human or humans).ti,ab.))
5 and 6
limit 7 to dd=20150101‐20210227

Cochrane Database of Systematic Reviews (CDSR)

videolaryngoscop*
((video* or indirect) near/5 laryngoscop*)
hyperangulat*
(Airtraq or Pentax or “King Vision” or “Airway Scope” or Vividtrac or “Res Q Scope” or Storz or McGrath or Glidescope or ClearVue or Truview or Bullard or CoPilot or “UE Scope” or UEScope or “I view” or “C MAC” or Intubrite or Anatech or Coopdech or Venner)
#1 or #2 or #3 or #4
#5 in Trials

Web of Science

TS=videolaryngoscop*
TS=((video* or indirect) near/5 laryngoscop*)
TS=hyperangulat*
TS=(Airtraq or Pentax or “King Vision” or “Airway Scope” or Vividtrac or “Res Q Scope” or Storz or McGrath or Glidescope or ClearVue or Truview or Bullard or CoPilot or “UE Scope” or UEScope or “I view” or “C MAC” or Intubrite or Anatech or Coopdech or Venner)
#4 OR #3 OR #2 OR #1
TS=(randomised OR randomized OR randomisation OR randomization OR placebo* OR (random* AND (allocat* OR assign*) ) OR (blind* AND (single OR double OR treble OR triple) ))
#6 AND #5
#7 AND PY=(2015‐2021)

ClinicalTrials.gov

Other terms: videolaryngoscopy OR “video laryngoscopy” OR videolaryngoscope OR “video laryngoscope” OR “indirect laryngoscopy” OR “indirect laryngoscope” OR Airtraq OR “King Vision” OR McGrath OR Glidescope OR “C MAC” OR C‐MAC

Filters: Interventional Studies | Adult

WHO International Clinical Trials Registry Platform (ICTRP)

videolaryngoscope OR video laryngoscope OR videolaryngoscopy OR video laryngoscopy OR indirect laryngoscopy OR indirect laryngoscope

Appendix 3. Template data extraction form

Methods	Randomized controlled trial; parallel design or cross‐over design Quasi‐randomized controlled trial; parallel design or cross‐over design
Participants	Total number of participants: Country: Setting: Inclusion criteria: Exclusion criteria: Baseline characteristics: Intervention 1 (specify by name) Age, mean (SD): X (± X) years Gender M/F, n: Weight, mean (SD): X (± X) kg Height, mean (SD): X (± X) m BMI, mean (SD): X (± X) kg/m² ASA I/II/III/IV, n: Mallampati 1/2/3/4, n: Intervention 2 (specify by name) Age, mean (SD): X (± X) years Gender M/F, n: Weight, mean (SD): X (± X) kg Height, mean (SD): X (± X) m BMI, mean (SD): X (± X) kg/m² ASA I/II/III/IV, n: Mallampati 1/2/3/4, n: Notes: (e.g. pregnancy, obesity, urgency of intubation)
Interventions	General details: to include number of intubators (and their skills and experience), use of additional equipment (stylet, bougie) Intervention 1 (specify by name) Randomized = n; losses = n; analysed = n blade size, other descriptors Intervention 2 (specify by name) Randomized = n; losses = n; analysed = n blade size, other descriptors Videolaryngoscope classification: Hyperangulated, Macintosh‐style, Channelled Notes:
Outcomes	Outcomes relevant to the review reported by study authors:list outcomes reported by authors, list outcomes of interest to the review and describe definitions of outcomes, do not report results Dichotomous outcomes: Failed intubation: Hypoxia: Number of attempts: Airway trauma: Patient‐reported sore throat: Cormack‐Lehane grade: Mortality: Continuous outcomes: Time for tracheal intubation: Intubation Difficulty Scale (IDS): POGO score: Notes:
Notes	Funding/sponsor/declarations of interest: Study dates:

Figure 1

Flow diagram

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Figure 2

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies

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Figure 3

Risk of bias summary: review authors' judgements about each risk of bias item for each included study. Blank spaces indicate we did not complete a risk of bias assessment because we were not able to extract any relevant data for our chosen outcomes.

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Figure 4

Funnel plot of comparison: Macintosh‐style videolaryngoscopy versus direct laryngoscopy, outcome 1.1, failed intubation

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Figure 5

Forest plot of comparison: hyperangulated videolaryngoscopy, subgroup analysis of failed intubation in participants with predicted, known or simulated features of airway difficulty

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Figure 6

Funnel plot of comparison: channelled videolaryngoscopy versus direct laryngoscopy, outcome 3.3, successful first attempt

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Analysis 1.1

Comparison 1: Macintosh‐style VL versus DL, Outcome 1: Failed intubation

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Analysis 1.2

Comparison 1: Macintosh‐style VL versus DL, Outcome 2: Hypoxaemia

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Analysis 1.3

Comparison 1: Macintosh‐style VL versus DL, Outcome 3: Successful first attempt

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Analysis 1.4

Comparison 1: Macintosh‐style VL versus DL, Outcome 4: Oesophageal intubation

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Analysis 1.5

Comparison 1: Macintosh‐style VL versus DL, Outcome 5: Dental trauma

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Analysis 1.6

Comparison 1: Macintosh‐style VL versus DL, Outcome 6: Cormack‐Lehane (CL) grade

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Analysis 1.7

Comparison 1: Macintosh‐style VL versus DL, Outcome 7: Time for tracheal intubation

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Analysis 1.8

Comparison 1: Macintosh‐style VL versus DL, Outcome 8: Patient‐reported sore throat

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Analysis 1.9

Comparison 1: Macintosh‐style VL versus DL, Outcome 9: Number of attempts

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Analysis 1.10

Comparison 1: Macintosh‐style VL versus DL, Outcome 10: Intubation Difficulty Scale (IDS)

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Analysis 1.11

Comparison 1: Macintosh‐style VL versus DL, Outcome 11: POGO Score

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Analysis 1.12

Comparison 1: Macintosh‐style VL versus DL, Outcome 12: Mortality

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Analysis 1.13

Comparison 1: Macintosh‐style VL versus DL, Outcome 13: Subgroup analysis of failed intubation: airway difficulty

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Analysis 2.1

Comparison 2: Hyperangulated VL versus DL, Outcome 1: Failed intubation

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Analysis 2.2

Comparison 2: Hyperangulated VL versus DL, Outcome 2: Hypoxaemia

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Analysis 2.3

Comparison 2: Hyperangulated VL versus DL, Outcome 3: Successful first attempt

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Analysis 2.4

Comparison 2: Hyperangulated VL versus DL, Outcome 4: Oesophageal intubation

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Analysis 2.5

Comparison 2: Hyperangulated VL versus DL, Outcome 5: Dental trauma

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Analysis 2.6

Comparison 2: Hyperangulated VL versus DL, Outcome 6: Cormack‐Lehane (CL) grade

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Analysis 2.7

Comparison 2: Hyperangulated VL versus DL, Outcome 7: Time for tracheal intubation

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Analysis 2.8

Comparison 2: Hyperangulated VL versus DL, Outcome 8: Patient‐reported sore throat

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Analysis 2.9

Comparison 2: Hyperangulated VL versus DL, Outcome 9: Number of attempts

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Analysis 2.10

Comparison 2: Hyperangulated VL versus DL, Outcome 10: Intubation Difficulty Scale (IDS)

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Analysis 2.11

Comparison 2: Hyperangulated VL versus DL, Outcome 11: POGO Score

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Analysis 2.12

Comparison 2: Hyperangulated VL versus DL, Outcome 12: Mortality

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Analysis 2.13

Comparison 2: Hyperangulated VL versus DL, Outcome 13: Subgroup analysis of failed intubation: airway difficulty

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Analysis 3.1

Comparison 3: Channelled VL versus DL, Outcome 1: Failed intubation

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Analysis 3.2

Comparison 3: Channelled VL versus DL, Outcome 2: Hypoxaemia

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Analysis 3.3

Comparison 3: Channelled VL versus DL, Outcome 3: Successful first attempt

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Analysis 3.4

Comparison 3: Channelled VL versus DL, Outcome 4: Oesophageal intubation

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Analysis 3.5

Comparison 3: Channelled VL versus DL, Outcome 5: Dental trauma

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Analysis 3.6

Comparison 3: Channelled VL versus DL, Outcome 6: Cormack‐Lehane (CL) grade

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Analysis 3.7

Comparison 3: Channelled VL versus DL, Outcome 7: Time for tracheal intubation

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Analysis 3.8

Comparison 3: Channelled VL versus DL, Outcome 8: Patient‐reported sore throat

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Analysis 3.9

Comparison 3: Channelled VL versus DL, Outcome 9: Number of attempts

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Analysis 3.10

Comparison 3: Channelled VL versus DL, Outcome 10: Intubation Difficulty Scale (IDS)

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Analysis 3.11

Comparison 3: Channelled VL versus DL, Outcome 11: POGO Score

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Analysis 3.12

Comparison 3: Channelled VL versus DL, Outcome 12: Subgroup analysis of failed intubation: airway difficulty

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Analysis 4.1

Comparison 4: VL versus DL (all devices combined), Outcome 1: Failed intubation

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Analysis 4.2

Comparison 4: VL versus DL (all devices combined), Outcome 2: Hypoxia

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Analysis 4.3

Comparison 4: VL versus DL (all devices combined), Outcome 3: Successful first attempt

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Analysis 4.4

Comparison 4: VL versus DL (all devices combined), Outcome 4: Oesophageal intubation

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Analysis 4.5

Comparison 4: VL versus DL (all devices combined), Outcome 5: Subgroup analysis of failed intubation: theatre versus non‐theatre

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Analysis 4.6

Comparison 4: VL versus DL (all devices combined), Outcome 6: Subgroup analysis of failed intubation: obesity

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Analysis 4.7

Comparison 4: VL versus DL (all devices combined), Outcome 7: Subgroup analysis of failed intubation: airway difficulty

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Analysis 4.8

Comparison 4: VL versus DL (all devices combined), Outcome 8: Subgroup analysis of failed intubation: intubator experience

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Summary of findings 1. Macintosh‐style videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation

Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
Macintosh‐style videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation
Patient or population: adults undergoing tracheal intubation Setting: hospital and out‐of‐hospital; international Intervention: Macintosh‐style videolaryngoscopy Comparison: direct laryngoscopy
Outcomes	Risk with direct laryngoscopy	Risk with Macintosh‐style videolaryngoscopy	Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
Failed intubation	Study population		RR 0.41 (0.26 to 0.65)	4615 (41 RCTs)	⊕⊕⊕⊝ Moderate^a
Failed intubation	65 per 1000	27 per 1000 (17 to 42)	RR 0.41 (0.26 to 0.65)	4615 (41 RCTs)	⊕⊕⊕⊝ Moderate^a
Hypoxaemia	Study population		RR 0.72 (0.52 to 0.99)	2127 (16 RCTs)	⊕⊕⊕⊝ Moderate^a
Hypoxaemia	106 per 1000	76 per 1000 (55 to 105)	RR 0.72 (0.52 to 0.99)	2127 (16 RCTs)	⊕⊕⊕⊝ Moderate^a
Successful first attempt	Study population		RR 1.05 (1.02 to 1.09)	7311 (42 RCTs)	⊕⊕⊝⊝ Low^a,b
Successful first attempt	813 per 1000	854 per 1000 (830 to 887)	RR 1.05 (1.02 to 1.09)	7311 (42 RCTs)	⊕⊕⊝⊝ Low^a,b
Oesophageal intubation	Study population		RR 0.51 (0.22 to 1.21)	2404 (14 RCTs)	⊕⊕⊝⊝ Low^a,c
Oesophageal intubation	29 per 1000	15 per 1000 (6 to 36)	RR 0.51 (0.22 to 1.21)	2404 (14 RCTs)	⊕⊕⊝⊝ Low^a,c
Dental trauma	Study population		RR 0.68 (0.16 to 2.89)	2297 (18 RCTs)	⊕⊝⊝⊝ Very low^a,d
Dental trauma	4 per 1000	2 per 1000 (1 to 10)	RR 0.68 (0.16 to 2.89)	2297 (18 RCTs)	⊕⊝⊝⊝ Very low^a,d
Cormack‐Lehane grade	Study population		RR 0.38 (0.29 to 0.48)	4368 (38 RCTs)	⊕⊕⊕⊝ Moderate^a,b	Data presented for frequency of Cormack‐Lehane grade 3 and 4 views
Cormack‐Lehane grade	196 per 1000	75 per 1000 (57 to 94)	RR 0.38 (0.29 to 0.48)	4368 (38 RCTs)	⊕⊕⊕⊝ Moderate^a,b
Time for tracheal intubation	See comment	See comment	‐	4061 (35 RCTs)	⊕⊝⊝⊝ Very low^a,e	High level of statistical heterogeneity between studies; therefore meta‐analysis not completed
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RCT: randomized controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.
^aWe downgraded by one level for risk of performance bias due to the lack of blinding. ^bWe downgraded by one level for inconsistency because we noted considerable statistical heterogeneity. ^cWe downgraded by one level for imprecision because the confidence intervals indicated possible benefits as well as harms. ^dWe downgraded by two levels for imprecision because the frequency of events was small and the confidence intervals indicated possible benefits as well as harms. ^eWe downgraded by two levels for inconsistency because we noted extremely high statistical heterogeneity (I² = 96%).

Summary of findings 1. Macintosh‐style videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation

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Summary of findings 2. Hyperangulated videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation

Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
Hyperangulated videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation
Patient or population: adults undergoing tracheal intubation Setting: hospital and out‐of‐hospital; international Intervention: hyperangulated videolaryngoscopy Comparison: direct laryngoscopy
Outcomes	Risk with direct laryngoscopy	Risk with hyperangulated videolaryngoscopy	Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
Failed intubation	Study population		RR 0.51 (0.34 to 0.76)	7146 (63 RCTs)	⊕⊕⊕⊝ Moderate^a
Failed intubation	56 per 1000	29 per 1000 (19 to 43)	RR 0.51 (0.34 to 0.76)	7146 (63 RCTs)	⊕⊕⊕⊝ Moderate^a
Hypoxaemia	Study population		RR 0.49 (0.22 to 1.11)	1691 (15 RCTs)	⊕⊕⊝⊝ Low^a,b
Hypoxaemia	44 per 1000	22 per 1000 (10 to 49)	RR 0.49 (0.22 to 1.11)	1691 (15 RCTs)	⊕⊕⊝⊝ Low^a,b
Successful first attempt	Study population		RR 1.03 (1.00 to 1.05)	8086 (66 RCTs)	⊕⊕⊝⊝ Low^a,c
Successful first attempt	854 per 1000	879 per 1000 (854 to 896)	RR 1.03 (1.00 to 1.05)	8086 (66 RCTs)	⊕⊕⊝⊝ Low^a,c
Oesophageal intubation	Study population		RR 0.39 (0.18 to 0.81)	1968 (14 RCTs)	⊕⊕⊕⊝ Moderate^a
Oesophageal intubation	26 per 1000	10 per 1000 (5 to 21)	RR 0.39 (0.18 to 0.81)	1968 (14 RCTs)	⊕⊕⊕⊝ Moderate^a
Dental trauma	Study population		RR 0.51 (0.16 to 1.59)	3497 (30 RCTs)	⊕⊝⊝⊝ Very low^a,d
Dental trauma	4 per 1000	2 per 1000 (1 to 7)	RR 0.51 (0.16 to 1.59)	3497 (30 RCTs)	⊕⊝⊝⊝ Very low^a,d
Cormack‐Lehane grade	Study population		RR 0.15 (0.10 to 0.24)	6058 (54 RCTs)	⊕⊕⊕⊝ Moderate^a,c	Data presented for frequency of Cormack‐Lehane grade 3 and 4 views
Cormack‐Lehane grade	189 per 1000	28 per 1000 (19 to 45)	RR 0.15 (0.10 to 0.24)	6058 (54 RCTs)	⊕⊕⊕⊝ Moderate^a,c
Time for tracheal intubation	see comment	see comment	‐	6644 (59 RCTs)	⊕⊝⊝⊝ Very low^a,e	High level of statistical heterogeneity between studies; therefore meta‐analysis not completed
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RCT: randomized controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.
^aWe downgraded by one level for risk of performance bias due to the lack of blinding. ^bWe downgraded by one level for imprecision because the confidence intervals indicated possible benefits as well as harms. ^cWe downgraded by one level for inconsistency because we noted considerable statistical heterogeneity. ^dWe downgraded by two levels for imprecision because the frequency of events was small and the confidence intervals indicated possible benefits as well as harms. ^eWe downgraded by two levels for inconsistency because we noted extremely high statistical heterogeneity (I² = 99%).

Summary of findings 2. Hyperangulated videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation

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Summary of findings 3. Channelled videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation

Outcomes	*Anticipated absolute effects^ (95% CI)**		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
Channelled videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation
Patient or population: adults undergoing tracheal intubation Setting: hospital and out‐of‐hospital; international Intervention: channelled videolaryngoscopy Comparison: direct laryngoscopy
Outcomes	Risk with direct laryngoscopy	Risk with channelled videolaryngoscopy	Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
Failed intubation	Study population		RR 0.43 (0.30 to 0.61)	5367 (53 RCTs)	⊕⊕⊕⊝ Moderate^a
Failed intubation	44 per 1000	19 per 1000 (13 to 27)	RR 0.43 (0.30 to 0.61)	5367 (53 RCTs)	⊕⊕⊕⊝ Moderate^a
Hypoxia	Study population		RR 0.25 (0.12 to 0.50)	1966 (15 RCTs)	⊕⊕⊕⊝ Moderate^a
Hypoxia	42 per 1000	10 per 1000 (5 to 21)	RR 0.25 (0.12 to 0.50)	1966 (15 RCTs)	⊕⊕⊕⊝ Moderate^a
Successful first attempt	Study population		RR 1.10 (1.05 to 1.15)	5210 (47 RCTs)	⊕⊕⊝⊝ Very low^a,b,c
Successful first attempt	826 per 1000	909 per 1000 (868 to 950)	RR 1.10 (1.05 to 1.15)	5210 (47 RCTs)	⊕⊕⊝⊝ Very low^a,b,c
Oesophageal intubation	Study population		RR 0.54 (0.17 to 1.75)	1756 (16 RCTs)	⊕⊕⊝⊝ Low^a,d
Oesophageal intubation	34 per 1000	19 per 1000 (6 to 60)	RR 0.54 (0.17 to 1.75)	1756 (16 RCTs)	⊕⊕⊝⊝ Low^a,d
Dental trauma	Study population		RR 0.52 (0.13 to 2.12)	2375 (29 RCTs)	⊕⊝⊝⊝ Very low^a,e
Dental trauma	3 per 1000	2 per 1000 (0 to 7)	RR 0.52 (0.13 to 2.12)	2375 (29 RCTs)	⊕⊝⊝⊝ Very low^a,e
Cormack‐Lehane grade	Study population		RR 0.14 (0.09 to 0.21)	3955 (40 RCTs)	⊕⊕⊕⊝ Moderate^a,b	Data presented for frequency of Cormack‐Lehane grade 3 and 4 views
Cormack‐Lehane grade	194 per 1000	27 per 1000 (17 to 41)	RR 0.14 (0.09 to 0.21)	3955 (40 RCTs)	⊕⊕⊕⊝ Moderate^a,b
Time for tracheal intubation	see comment	see comment	‐	5676 (57 RCTs)	⊕⊝⊝⊝ Very low^a,f	High level of statistical heterogeneity between studies; therefore meta‐analysis not completed
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RCT: randomized controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.
^aWe downgraded by one level for risk of performance bias due to the lack of blinding. ^bWe downgraded by one level for inconsistency because we noted considerable statistical heterogeneity. ^cWe downgraded by one level for suspicion of publication bias. ^dWe downgraded by one level for imprecision because the confidence intervals indicated possible benefits as well as harms. ^eWe downgraded by two levels for imprecision because the frequency of events was small and the confidence intervals indicated possible benefits as well as harms. ^fWe downgraded by two levels for inconsistency because we noted extremely high statistical heterogeneity (I² = 98%).

Summary of findings 3. Channelled videolaryngoscopy compared to direct laryngoscopy for adults undergoing tracheal intubation

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Comparison 1. Macintosh‐style VL versus DL

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Failed intubation Show forest plot	41	4615	Risk Ratio (M‐H, Random, 95% CI)	0.41 [0.26, 0.65]

1.2 Hypoxaemia Show forest plot	16	2127	Risk Ratio (M‐H, Random, 95% CI)	0.72 [0.52, 0.99]

1.3 Successful first attempt Show forest plot	42	7311	Risk Ratio (M‐H, Random, 95% CI)	1.05 [1.02, 1.09]

1.4 Oesophageal intubation Show forest plot	14	2404	Risk Ratio (M‐H, Random, 95% CI)	0.51 [0.22, 1.21]

1.5 Dental trauma Show forest plot	18	2297	Risk Ratio (M‐H, Random, 95% CI)	0.68 [0.16, 2.89]

1.6 Cormack‐Lehane (CL) grade Show forest plot	38	13104	Risk Ratio (M‐H, Random, 95% CI)	0.90 [0.81, 1.00]

1.6.1 Cormack‐Lehane 1	38	4368	Risk Ratio (M‐H, Random, 95% CI)	1.50 [1.39, 1.63]
1.6.2 Cormack‐Lehane 2	38	4368	Risk Ratio (M‐H, Random, 95% CI)	0.62 [0.51, 0.76]
1.6.3 Cormack‐Lehane 3‐4	38	4368	Risk Ratio (M‐H, Random, 95% CI)	0.38 [0.29, 0.48]
1.7 Time for tracheal intubation Show forest plot	35		Mean Difference (IV, Random, 95% CI)	Subtotals only

1.8 Patient‐reported sore throat Show forest plot	17	1960	Risk Ratio (M‐H, Random, 95% CI)	0.85 [0.68, 1.07]

1.9 Number of attempts Show forest plot	31	6480	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.98, 1.08]

1.9.1 1 attempt	31	3240	Risk Ratio (M‐H, Random, 95% CI)	1.05 [1.01, 1.10]
1.9.2 2‐4 attempts	31	3240	Risk Ratio (M‐H, Random, 95% CI)	0.68 [0.46, 1.01]
1.10 Intubation Difficulty Scale (IDS) Show forest plot	4	801	Risk Ratio (M‐H, Random, 95% CI)	1.05 [0.88, 1.25]

1.10.1 IDS 0	4	267	Risk Ratio (M‐H, Random, 95% CI)	1.22 [0.87, 1.72]
1.10.2 IDS 1‐5	4	267	Risk Ratio (M‐H, Random, 95% CI)	1.04 [0.84, 1.28]
1.10.3 IDS > 5	4	267	Risk Ratio (M‐H, Random, 95% CI)	0.60 [0.25, 1.45]
1.11 POGO Score Show forest plot	5		Mean Difference (IV, Random, 95% CI)	Subtotals only

1.12 Mortality Show forest plot	3	719	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.82, 1.24]

1.13 Subgroup analysis of failed intubation: airway difficulty Show forest plot	37	3925	Risk Ratio (M‐H, Random, 95% CI)	0.40 [0.23, 0.68]

1.13.1 Predicted, known or simulated difficulty	12	1393	Risk Ratio (M‐H, Random, 95% CI)	0.37 [0.19, 0.74]
1.13.2 No difficulty	25	2532	Risk Ratio (M‐H, Random, 95% CI)	0.42 [0.16, 1.10]

Comparison 1. Macintosh‐style VL versus DL

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Comparison 2. Hyperangulated VL versus DL

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
2.1 Failed intubation Show forest plot	63	7146	Risk Ratio (M‐H, Random, 95% CI)	0.51 [0.34, 0.76]

2.2 Hypoxaemia Show forest plot	15	1691	Risk Ratio (M‐H, Random, 95% CI)	0.49 [0.22, 1.11]

2.3 Successful first attempt Show forest plot	66	8086	Risk Ratio (M‐H, Random, 95% CI)	1.03 [1.00, 1.05]

2.4 Oesophageal intubation Show forest plot	14	1968	Risk Ratio (M‐H, Random, 95% CI)	0.39 [0.18, 0.81]

2.5 Dental trauma Show forest plot	30	3497	Risk Ratio (M‐H, Random, 95% CI)	0.51 [0.16, 1.59]

2.6 Cormack‐Lehane (CL) grade Show forest plot	54	18174	Risk Ratio (M‐H, Random, 95% CI)	0.83 [0.74, 0.94]

2.6.1 Cormack‐Lehane 1	54	6058	Risk Ratio (M‐H, Random, 95% CI)	1.77 [1.56, 2.01]
2.6.2 Cormack‐Lehane 2	54	6058	Risk Ratio (M‐H, Random, 95% CI)	0.54 [0.46, 0.63]
2.6.3 Cormack‐Lehane 3‐4	54	6058	Risk Ratio (M‐H, Random, 95% CI)	0.15 [0.10, 0.24]
2.7 Time for tracheal intubation Show forest plot	59		Mean Difference (IV, Random, 95% CI)	Subtotals only

2.8 Patient‐reported sore throat Show forest plot	31	3725	Risk Ratio (M‐H, Random, 95% CI)	0.81 [0.66, 1.00]

2.9 Number of attempts Show forest plot	50	11004	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.99, 1.04]

2.9.1 1 attempt	50	5502	Risk Ratio (M‐H, Random, 95% CI)	1.02 [1.00, 1.05]
2.9.2 2‐4 attempts	50	5502	Risk Ratio (M‐H, Random, 95% CI)	0.84 [0.66, 1.08]
2.10 Intubation Difficulty Scale (IDS) Show forest plot	10		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected

2.10.1 IDS 0	10		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
2.10.2 IDS 1‐5	10		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
2.10.3 IDS > 5	10		Risk Ratio (M‐H, Random, 95% CI)	Totals not selected
2.11 POGO Score Show forest plot	14		Mean Difference (IV, Random, 95% CI)	Subtotals only

2.12 Mortality Show forest plot	3	826	Risk Ratio (M‐H, Random, 95% CI)	1.15 [0.73, 1.79]

2.13 Subgroup analysis of failed intubation: airway difficulty Show forest plot	59	6607	Risk Ratio (M‐H, Random, 95% CI)	0.45 [0.30, 0.68]

2.13.1 Predicted, known or simulated difficulty	15	1520	Risk Ratio (M‐H, Random, 95% CI)	0.29 [0.17, 0.48]
2.13.2 No difficulty	44	5087	Risk Ratio (M‐H, Random, 95% CI)	0.64 [0.38, 1.06]

Comparison 2. Hyperangulated VL versus DL

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Comparison 3. Channelled VL versus DL

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
3.1 Failed intubation Show forest plot	53	5367	Risk Ratio (M‐H, Random, 95% CI)	0.43 [0.30, 0.61]

3.2 Hypoxaemia Show forest plot	15	1966	Risk Ratio (M‐H, Random, 95% CI)	0.25 [0.12, 0.50]

3.3 Successful first attempt Show forest plot	47	5210	Risk Ratio (M‐H, Random, 95% CI)	1.10 [1.05, 1.15]

3.4 Oesophageal intubation Show forest plot	16	1756	Risk Ratio (M‐H, Random, 95% CI)	0.54 [0.17, 1.75]

3.5 Dental trauma Show forest plot	29	2375	Risk Ratio (M‐H, Random, 95% CI)	0.52 [0.13, 2.12]

3.6 Cormack‐Lehane (CL) grade Show forest plot	40	11865	Risk Ratio (M‐H, Random, 95% CI)	0.70 [0.58, 0.85]

3.6.1 Cormack‐Lehane 1	40	3955	Risk Ratio (M‐H, Random, 95% CI)	2.01 [1.75, 2.31]
3.6.2 Cormack‐Lehane 2	40	3955	Risk Ratio (M‐H, Random, 95% CI)	0.24 [0.17, 0.35]
3.6.3 Cormack‐Lehane 3‐4	40	3955	Risk Ratio (M‐H, Random, 95% CI)	0.14 [0.09, 0.21]
3.7 Time for tracheal intubation Show forest plot	57		Mean Difference (IV, Random, 95% CI)	Subtotals only

3.8 Patient‐reported sore throat Show forest plot	18	1666	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.73, 1.14]

3.9 Number of attempts Show forest plot	38	8314	Risk Ratio (M‐H, Random, 95% CI)	1.05 [1.00, 1.10]

3.9.1 1 attempt	38	4157	Risk Ratio (M‐H, Random, 95% CI)	1.09 [1.04, 1.14]
3.9.2 2‐4 attempts	38	4157	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.33, 0.68]
3.10 Intubation Difficulty Scale (IDS) Show forest plot	16	3012	Risk Ratio (M‐H, Random, 95% CI)	0.84 [0.59, 1.19]

3.10.1 IDS 0	16	1004	Risk Ratio (M‐H, Random, 95% CI)	3.34 [2.43, 4.60]
3.10.2 IDS 1‐5	16	1004	Risk Ratio (M‐H, Random, 95% CI)	0.38 [0.27, 0.53]
3.10.3 IDS > 5	16	1004	Risk Ratio (M‐H, Random, 95% CI)	0.21 [0.12, 0.37]
3.11 POGO Score Show forest plot	5		Mean Difference (IV, Random, 95% CI)	Subtotals only

3.12 Subgroup analysis of failed intubation: airway difficulty Show forest plot	52	5287	Risk Ratio (M‐H, Random, 95% CI)	0.42 [0.29, 0.62]

3.12.1 Predicted, known or simulated difficulty	20	1433	Risk Ratio (M‐H, Random, 95% CI)	0.22 [0.10, 0.49]
3.12.2 No difficulty	32	3854	Risk Ratio (M‐H, Random, 95% CI)	0.53 [0.32, 0.88]

Comparison 3. Channelled VL versus DL

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Comparison 4. VL versus DL (all devices combined)

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
4.1 Failed intubation Show forest plot	139	16228	Risk Ratio (M‐H, Random, 95% CI)	0.44 [0.35, 0.56]

4.2 Hypoxia Show forest plot	41	5434	Risk Ratio (M‐H, Random, 95% CI)	0.61 [0.44, 0.85]

4.3 Successful first attempt Show forest plot	138	19797	Risk Ratio (M‐H, Random, 95% CI)	1.05 [1.03, 1.07]

4.4 Oesophageal intubation Show forest plot	40	5768	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.29, 0.77]

4.5 Subgroup analysis of failed intubation: theatre versus non‐theatre Show forest plot	141	16450	Risk Ratio (M‐H, Random, 95% CI)	0.46 [0.36, 0.59]

4.5.1 Theatre	130	14604	Risk Ratio (M‐H, Random, 95% CI)	0.41 [0.32, 0.54]
4.5.2 Non‐theatre	11	1846	Risk Ratio (M‐H, Random, 95% CI)	0.68 [0.42, 1.09]
4.6 Subgroup analysis of failed intubation: obesity Show forest plot	133	14881	Risk Ratio (M‐H, Random, 95% CI)	0.43 [0.32, 0.56]

4.6.1 Obese	13	1085	Risk Ratio (M‐H, Random, 95% CI)	0.25 [0.13, 0.46]
4.6.2 Non‐obese	120	13796	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.35, 0.62]
4.7 Subgroup analysis of failed intubation: airway difficulty Show forest plot	132	14999	Risk Ratio (M‐H, Random, 95% CI)	0.42 [0.32, 0.54]

4.7.1 Predicted, known or simulated difficulty	42	4100	Risk Ratio (M‐H, Random, 95% CI)	0.32 [0.23, 0.44]
4.7.2 No difficulty	90	10899	Risk Ratio (M‐H, Random, 95% CI)	0.54 [0.38, 0.78]
4.8 Subgroup analysis of failed intubation: intubator experience Show forest plot	115	13095	Risk Ratio (M‐H, Random, 95% CI)	0.44 [0.34, 0.58]

4.8.1 Expert	98	10939	Risk Ratio (M‐H, Random, 95% CI)	0.41 [0.33, 0.50]
4.8.2 Non‐expert	17	2156	Risk Ratio (M‐H, Random, 95% CI)	0.62 [0.32, 1.18]

Comparison 4. VL versus DL (all devices combined)

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La vidéolaryngoscopie par rapport à la laryngoscopie directe dans l’intubation trachéale de l’adulte

Appendices

Appendix 1. Videolaryngoscope classification

Appendix 2. Search strategies

MEDLINE ALL (OvidSP)

Embase (OvidSP)

Cochrane Database of Systematic Reviews (CDSR)

Web of Science

ClinicalTrials.gov

WHO International Clinical Trials Registry Platform (ICTRP)

Appendix 3. Template data extraction form

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Appendices

Appendix 1. Videolaryngoscope classification

Appendix 2. Search strategies

MEDLINE ALL (OvidSP)

Embase (OvidSP)

Cochrane Database of Systematic Reviews (CDSR)

Web of Science

ClinicalTrials.gov

WHO International Clinical Trials Registry Platform (ICTRP)

Appendix 3. Template data extraction form

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Instituciones a las que se accedió previamente

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