Video laryngoscopes to help intubation in people with difficult airways

Cabrini et al. (2018)

Study size, design and location

Systematic review and meta-analyses of 9 RCTs comparing video laryngoscopy with direct laryngoscopy in critically ill adults; 4 of which analysed anticipated difficult airway subgroups (including a total of 1,342 laryngoscopy procedures in these populations).

Multiple settings including: trauma resuscitation unit, emergency department, and ICU.

Multiple users including: emergency medicine residents, anaesthesiology residents, attending anaesthesiologists, nurse anaesthetists, senior residents, ICU clinicians.

Locations of primary studies not reported.

Intervention and comparator(s)

Intervention: Video laryngoscopes (n=667): GlideScope (n=303), McGrath Mac (n=186) and C-MAC (used in 2 studies: n=178).

Comparator: Direct laryngoscopes (n=675).

Key outcomes

Primary outcomes included: survival to hospital discharge, overall successful intubation, first-pass success rate.

No study found any difference in these primary outcomes in patients with difficult airways.

The 2 largest RCTs reported an increased incidence of severe complications with video laryngoscopy in post-hoc analyses in a critically ill population, including: increased time to intubation, greater incidence of severe desaturation episodes, highest mortality rate in the group with severe head injury and increased incidence of life-threatening complications.

Strengths and limitations

There was no meta-analysis conducted on the 4 studies that reported anticipated difficult airway subgroups.

The comparator direct laryngoscopy devices were not identified.

Non-UK findings may not be generalisable to clinical practice in the NHS.

Hoshijima et al. (2018)

Study size, design and location

Systematic review and meta-analyses of 11 studies describing 13 RCTs of video laryngoscopy versus direct laryngoscopy with Macintosh blades in adults with obesity (including a total of 1,044 laryngoscopy procedures).

Setting and user: operating room, by experienced laryngologists.

Locations of primary studies not reported.

Intervention and comparator(s)

Intervention: Video laryngoscopes (n=527): Airtraq (used in 5 studies, n=286), GlideScope (used in 2 studies, n=80), McGrath (n=40), Airwayscope (n=50), X-Lite (n=40), McGrath or GlideScope or Video-Mac (1 study using multiple devices, n=31).

Comparator: Direct laryngoscopes with Macintosh blades (n=517).

Key outcomes

Success rate of tracheal intubation was significantly higher, intubation time significantly lower and glottis visualisation superior with video laryngoscopes than the direct laryngoscopes with Macintosh blades.

Video laryngoscopes with and without tracheal tube guide channel were superior to direct laryngoscopes with Macintosh blades for all outcomes, except for video laryngoscope intubation time without a channel.

Strengths and limitations

Using the GRADE approach, the quality of evidence was low for success rate, very low for intubation time and very low for glottis visualisation.

The findings are specific to difficult airways associated with obesity.

Non-UK trials may not be generalisable to clinical practice in the NHS.

Lewis et al. (2017)

Study size, design and location

Systematic Cochrane review and meta-analyses of 64 RCTs of video laryngoscopy compared with laryngoscopy with Macintosh blades in adults. Of the 64 RCTs, 6 studies reported on a population with known or predicted difficult airway (including 2 studies that specified inclusion of patients with restricted cervical mobility), and 9 studies included patients whose airway was manipulated to simulate a difficult laryngoscopy (a total of 1,640 laryngoscopy procedures in a difficult airway population).

Multiple settings, including general anaesthesia, ICU and emergency department. The experience of users was not reported.

Locations of primary studies: Ireland (4 studies), Germany (3 studies), Japan (3 studies), USA (2 studies), Canada (2 studies), Singapore (1 study).

Intervention and comparator(s)

Intervention: Video laryngoscopes (n=912): C-MAC (4 studies, n=318), Pentax AWS (6 studies, n=252), GlideScope (5 studies, n=160), McGrath (1 study, n=44), and unknown device name in 5 studies (n=138).

Comparator: Direct laryngoscopes with Macintosh blades (n=728).

Key outcomes

Fewer intubation failures with video laryngoscopes when compared with direct laryngoscopes with Macintosh blades in patients with a known or predicted difficult airway, and in those with a simulated difficult airway.

Strengths and limitations

This Cochrane review provides a good summary of earlier evidence (up to February 2015).

Non-UK trials may not be generalisable to clinical practice in the NHS.

Pieters et al. (2017)

Study size, design and location

Systematic review and meta-analyses of 9 studies (RCTs and observational studies, including a total of 1,441 laryngoscopy procedures) of adults, with suspected difficult airway.

Setting and user: elective surgery intubations by anaesthetists with more than 2 years' experience with direct laryngoscopy.

Locations of primary studies not reported.

Intervention and comparator(s)

Intervention: Video laryngoscopes (n=900): GlideScope (used in 3 studies, n=184), C-MAC (used in 2 studies, n=204), Pentax AWS (n=320), McGrath (n=40), Airtraq (n=20), C-MAC D-Blade (n=32), Berci-Kaplan VLS (n=100).

Comparator: Direct laryngoscopes (n=541): Macintosh blade (used in 9 studies), Henderson straight blade (used in 1 study), not defined in 1 study.

Key outcomes

First-attempt success of intubations was greater for video laryngoscopes.

No significant differences in time until successful intubation, Cormack–Lehane grade, number of attempts, or dental trauma were found between video and direct laryngoscopy.

Strengths and limitations

The systematic review protocol excluded simulated difficult airways and specified anaesthetist user experience with direct laryngoscopy.

Non-UK trials may not be generalisable to clinical practice in the NHS.

Abbreviations: GRADE, Grading of Recommendations Assessment, Development and Evaluation; ICU, intensive care unit; RCT, randomised controlled trial.

Cook et al. (2018)

Study size, design and location

User survey study with 2 month feasibility trial stage.

Series of user surveys: pre-trial (anaesthetists), mid-trial (anaesthetists and anaesthetist assistants), end-of-trial (anaesthetists), 6 months after trial (anaesthetists) and 8 months after trial (anaesthetic trainees who were in department during 2 month feasibility trial).

Single centre (UK).

Intervention and comparator(s)

Intervention: C-MAC video laryngoscopes (mandated in use during the 2 month feasibility stage).

Comparator: C-MAC laryngoscopes with Macintosh blades used as direct vision laryngoscopes.

Video laryngoscopes remained available to users at the end of the feasibility stage and anaesthetists were able to choose between direct and indirect (video) C-MAC devices.

Key outcomes

Pre-trial survey (n=47 responders): 32% supported change to video laryngoscopy, 28% were against it (reasons included: training, patient safety, team dynamics).

Mid-trial survey (n=56 responders): approximately 830 intubations and extubations reported. 7 cases of delay of induction of anaesthesia or extubation, due to a C-MAC not being immediately available, were reported, 2 reports of device power failure, 1 failed intubation with device. 57% reported C-MAC video laryngoscopy had a positive effect on their practice, 8% a negative effect.

End-of-trial survey (n=44 responders): no new reports of clinical delays, device failures or failed intubations. 82% reported positive effect, 2% negative.

Six-month post-trial survey (n=27 responders): 89% supported change to video laryngoscopy, 4% against.

Eight-month post-trial survey (n=19 responders): 84% positive effect, 16% neutral, 0% negative effect.

Strengths and limitations

C-MAC device used due to its multipurpose design as a video laryngoscope or direct laryngoscope.

Feasibility stage would have included a difficult airway subgroup, but not exclusively, limiting the generalisability of this study to a difficult airway population.

UK user survey directly generalisable to clinical practice in the NHS.

Jones et al. (2018)

Study size, design and location

User survey (48 anaesthetic assistants)

Single centre (UK).

Intervention and comparator(s)

Intervention: C-MAC video laryngoscope.

Comparator: None.

Key outcomes

88% had over 2 years' experience of using the C-MAC device.

All responders reported that patient safety was improved using C-MAC when compared with standard laryngoscope with Macintosh blade: 63% strongly agreed, and 18% agreed. Most reported that C-MAC made it easier to see when laryngoscopy was difficult: 88% strongly agreed, 10% agreed. Most reported that training of laryngoscopy and intubation was improved: 75% strongly agreed, 23% agreed. Most reported that training of cricoid pressure for trainee operating department practitioners and anaesthetic nurses was improved: 54% strongly agreed, 33% agreed, 13% neither agreed nor disagreed.

42% reported that the need for decontamination of C-MAC was disadvantageous aspect of its use, 38% disagreed and 21% neither agreed nor disagreed. Need to share C-MAC screens between theatres was reported to be disadvantageous in 69%.

49 positive free-text comments were reported, including, for anticipated or unanticipated difficult airway management: improved ease of intubation, improved laryngeal view, and intubation of high-risk patients.

40 negative free-text comments were reported, including: logistics in decontamination, device availability, concerns over short battery life or possibility of power failure, concerns that anaesthetists could become deskilled in direct laryngoscopy.

Strengths and limitations

Not exclusively in difficult airway.

UK user survey directly generalisable to clinical practice in the NHS.

Cook and Kelly (2017)

Study size, design and location

Multi-centre (national survey sent to 335 NHS hospitals in UK).

Intervention and comparator(s)

Intervention: All video laryngoscopes including rigid intubation devices that use digital or optical imaging with intent of facilitating tracheal intubation: Airtraq, AP Venner, Bonfils, Bullard, C-MAC, C-MAC D-Blade, Coopdech, C-Trach, GlideScope, King Vision VL, Levitan FPS, McGrath 5, McGrath Mac, Pentax AWS, Shikani intubating stylet, Upsherscope, Wuscope.

Comparator: none.

Key outcomes

Total of 164 responses (teaching hospitals 26%, district general hospital with teaching affiliation 44%, district general hospital 16%, specialist paediatric hospital 3%, other specialist hospital 3%); 160 from consultants, 3 by associate specialists, 1 by senior specialist registrar.

92% reported availability of video laryngoscopy in at least 1 clinical area.

Of 804 NHS clinical areas in the 164 respondents' NHS hospitals, 52% reported availability of a video laryngoscope.

In all locations and overall, the top 3 devices were Airtraq (48% of all video laryngoscopy locations), GlideScope (18%), C-MAC (with or without D-Blade, 15%). 3 video laryngoscopy devices were not reported to be used at all (Coopdech, Upsherscope and Wuscope), and a further 4 by fewer than 5 respondents (Bullard, C-Trach, Levitan FPS, King VL).

Some degree of restriction of use was reported in 32% of anaesthetic departments, 58% of ICUs, 78% of emergency departments. Of the 131 respondents who described elective use of video laryngoscopy in the operating theatre, none reported routine use, less than one-third reported regular use, and 10% reported rare use.

A minority (4%) had formal clinical training on use of a video laryngoscope device, 4% practised "see one, do one, teach one" approach, 9% had no structured introduction, 48% trained on a mannequin, 34% had informal introduction into clinical practice.

Strengths and limitations

Survey closed 2014, therefore gives historic view of video laryngoscopy use. Not exclusively in difficult airway population, includes adult and paediatric patients.

UK user survey directly generalisable to clinical practice in the NHS.

Green et al. (2017)

Study size, design and location

Multi-centre (national survey sent to 1,758 non-trainee clinicians in Canadian hospitals).

Intervention and comparator(s)

Intervention: Video laryngoscopy

Comparator: Direct laryngoscopy

Survey included 3 clinical scenarios:

1) 67-year old female with congestive heart failure

2) 59-year old female with pneumonia

3) 29-year old male trauma patient in a cervical spine immobilisation collar and abrasions on head, chest, and abdomen.

Key outcomes

Responses from 882 clinicians: 73% emergency medicine, 27% ICU clinicians. Most practised at an academic hospital (79%) and had more than 5 years of experience (83%).

Across all 3 clinical scenarios, most clinicians selected a preference of direct laryngoscopy with a Macintosh blade (85%), followed by video laryngoscope (38%) and bougie-assisted direct laryngoscopy (20%).

Back-up devices used by clinicians if their primary intubation strategy was unsuccessful were: extraglottic device (59%) followed by percutaneous cricothyrotomy (5%).

Strengths and limitations

Gives an estimate of video laryngoscope use in Canada specific to emergent endotracheal intubation in critically ill patients.

Specific video laryngoscopy devices in use are not described.

Non-UK studies may not be generalisable to clinical practice in the NHS.

Wong et al. (2014)

Study size, design and location

Multi-centre (national survey sent to 2,532 anaesthesiologists in Canadian hospitals).

Intervention and comparator(s)

Intervention: Video laryngoscopy

Comparator: Direct laryngoscopy

Survey included 2 clinical scenarios: including:

1) an unanticipated difficult intubation

2) failed direct laryngoscopy.

Key outcomes

Responses from 997; 71% from teaching practice.

90% chose video laryngoscopy for the unanticipated difficult intubation scenario (where direct laryngoscopy had failed).

Previous experience with video laryngoscopy was reported as 27% on mannequin (one of lowest proportions alongside optical stylet with 26%), 99% reported use of video laryngoscopy on patients (the highest proportion when compared with awake/asleep flexible bronchoscope intubation, intubating laryngeal mask airway, optical stylet, retrograde wire set), 99% reported comfort in using video laryngoscopy.

Strengths and limitations

Potential selection bias in results (from 40% response rate, non-translation of survey into French excluding specific Canadian provinces, distributed via email only).

Non-UK studies may not be generalisable to clinical practice in the NHS.

Abbreviations: ICU, intensive care unit; RCT, randomised controlled trial.