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Three Part Question

In [adults requiring emergency department intubation] does the [use of the GlideScope videolaryngoscope] improve the [success rate of intubation]?

Clinical Scenario

A 34-year-old patient presents to the Emergency Department with altered level of consciousness from a suspected intracranial bleed. The decision is made to intubate him. You predict a difficult airway. As you gather your equipment, you wonder whether use of a new GlideScope device will help achieve better success at intubation as opposed to traditional direct laryngoscopy.

Search Strategy

Medline (1966 – 5/2010) using the OVID interface.

({glidescope.mp} AND {exp intubation/ OR intubation.mp OR intubat$.mp} AND {exp laryngoscopy/ OR laryngoscopy.mp OR laryngoscop$.mp})

Limits: English language; human

Further search of reference lists of relevant papers to find any papers missed by the search.

Search Outcome

54 papers were found of which three were of direct relevance. Others provided incidental supportive evidence (discussed in comments).

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Platts-Mills TF et al. 2009 USA	280 adult ED patients – GlideScope (GS) used in 63 (22%) vs Macintosh (M) in 217 (78%).	Prospective observational study over 18 months.	Primary: success with first intubation	233 (83%) intubated on 1st attempt.	Observational study. Selection bias as choice of laryngoscope left up to operator. No objective measurement of airway difficulty. Reasons for failure not stated. Single centre.
			Secondary: Time to intubation (TTI)	GS 42s v M 30s
			Secondary: failure rate	GS 9, M 17 (p=0.12)
Lim HC et al, 2009 Singapore	318 adult ED patients observed requiring intubation. GS used in 21 of these.	Prospective observational study over 6 months, single centre.	No formal study protocol. Data collected regarding operator identification, patient demographics, success of intubation, number of attempts, and difficulties encountered. Glottic view documented. TTI not recorded.	Successful use in 15 of 21 cases (72%). Cormack-Lehane (CL) grade I or II view in all cases even by novice users. No failure when GS used for predicted difficult airway. Main reason for failure was technical – required manipulation of the tube/stylet for intubation using GS.	Observational study. No standardization amongst operators on choice of device or method of assessing difficult airway. Single centre study. Small numbers. Time to intubation not recorded.
Choi HJ et al , 2010 Korea	Total of 3233 intubation attempts in 2543 adult ED patients - 345 attempts using GS in 303 patients (10.7%).	Prospective observational study over a 2 year period in 5 centres.	Data collected from web-based registry including device used, number of attempts at intubation, CL grade, percentage of glottic opening (POGO) score.	Overall success with either laryngoscope: GS 79.1% success, M 77.6% (p=0.538).	Observational study. Possibility of reporting errors due to use of multiple centres. Experience of intubator not factored in. No recording of time to achieve intubation.
			Specifically reviewed were success of first and rescue attempt at intubation.	Difficult airway identified: (503 patients 164 attempts at intubation with GS, 712 attempts with M): GS 80% success, M 50.4% success (p<0.001).
			Results analyzed to review “routine” airways and difficult airways.	CL grade 3 or 4 in GS 9.4% vs 22.4% in M in patients with difficult airways.

Comment(s)

The GlideScope video laryngoscope is one of several video laryngoscopes currently available to physicians. A search of the literature for GlideScope video laryngoscope usage shows numerous papers mainly from anaesthetic practice demonstrating both ease of intubation among relatively new and experienced users (4-7), demonstrable improvement in Cormack-Lehane scores, and a variety of other factors such as minimizing cervical spine movement in intubations where this is a concern (8). The GlideScope was chosen for this BestBet as it has been a common choice in many non-UK Emergency Departments and has been formally studied in the ED setting in contrast to the other videolaryngoscopes (at the time of this BestBet). Additionally, some UK EDs have started using it. The studies cited do not allow recommendation of the GlideScope over and above a direct laryngoscope for the “routine” ED intubation in the context of our 3-part question. On the other hand, the failure rates between the GlideScope and direct laryngoscope are also not statistically significant. However, there does appear to be support for its use in the difficult airway situation (either predicted or otherwise). Interestingly, in Platt-Mills’ study, in the 9 video laryngoscope failures at intubation, 7 were reintubated using a direct laryngoscope. Of the 17 direct laryngoscopy failures, none were “rescued” using a video laryngoscope (1). The reasoning behind this is not stated however. The other two studies did however show the role of the GlideScope as a rescue device in difficult airways (2,3). Only one study examined the time to intubation in an ED setting (1). This was significantly longer than with conventional laryngoscopy. The significance of this must be balanced with the clinical situation – certain pathophysiologic conditions will tolerate a degree of hypoxaemia better than others. The main perceived difficulty with the GlideScope, cited in both the anaesthetic and EM literature, is that the steep angle of the blade requires modification of the technique to actually insert the endotracheal tube once the glottis is visualized. Once this learning curve has been surmounted, however, the laryngoscope becomes easy to use. However, this perceived difficulty in infrequent users may have prevented some of the study intubators from choosing the device. New questions therefore arise with regards to use as only a difficult airway adjunct in the Emergency Department. Since a modified technique is required for its correct use, should it be used in routine airways as well so as to achieve this skill and therefore not make managing a difficult airway more difficult by adding an element of equipment unfamiliarity? If one decides to do this, would the skill of using a conventional direct laryngoscope disappear? In departments that fear this, should regular simulator-based training therefore be adopted to achieve the skill? As the number of ED-based studies is limited, continued study in the ED would be of benefit, although the inevitable controversies surrounding conducting a randomized controlled trial in the ED are difficult to surmount effectively in the setting of managing an emergency airway.

Editor Comment

CL, Cormack–Lehane; ED, emergency department; GS, GlideScope; M, Macintosh; TTI, time to intubation.

Clinical Bottom Line

There is no evidence in the current EM literature to show improved success rates of the GlideScope over conventional direct laryngoscopy in “routine” ED airway management. However, there is some support for its role in the difficult airway. More ED-based studies are required before this device can be fully recommended as a better intubating tool for all ED airway management.

References

1. Platts-Mills TF, Campagne D, Chinnock B et al. A Comparison of GlideScope Video Laryngoscopy Versus Direct Laryngoscopy Intubation in the Emergency Department. Acad Emerg Med 2009;16:866-871
2. Lim HC, Goh SH. Utilization of a GlideScope videolaryngoscope for orotracheal intubations in different emergency airway management settings. Eur J Emerg Med 2009;16:68-73.
3. Choi HJ, Kang H-G, Lim TH, et al. Endotracheal intubation using a GlideScope video laryngoscope by emergency physicians: a multicentre analysis of 345 attempts in adult patients. Emerg Med J 2010; 27:380-382
4. Sun DA, Warriner CB, Parsons DG et al. The GlideScope Video Laryngoscope: randomized clinical trial in 200 patients. Br J Anaesth 2005 Mar; 94(3):381-4.
5. Cooper RM, Pacey JA, Bishop MJ, et al. Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients. Can J Anaesth. 2005 Feb; 52(2):191-8.
6. Nouruzi-Sedeh P, Schumann M, Groeben H. Laryngoscopy via Macintosh Blade versus GlideScope – Success Rate and Time for Endotracheal Intubation in Untrained Medical Personnel. Anesthesiology 2009 Jan; 110(1):32-7
7. Lim TJ, Lim Y, Liu EHC. Evaluation of ease of intubation with the GlideScope or Macintosh laryngoscope by anaesthetists in simulated easy and difficult laryngoscopy. Anaesthesia. 2005 Feb; 60(2):180-3.
8. Turkstra TP, Craen RA, Pelz DM, et al. Cervical spine motion: a fluoroscopic comparison during intubation with lighted stylet, GlideScope, and Macintosh laryngoscope. Anesth Analg 2005;101:910-915.