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British Journal of Anaesthesia
BJA

The efficacy of GlideScope® videolaryngoscopy compared with direct laryngoscopy in children who are difficult to intubate: an analysis from the paediatric difficult intubation registry

  • Author Footnotes
    † Both authors contributed equally to the manuscript and are considered joint first authors.
    R. Park
    Footnotes
    † Both authors contributed equally to the manuscript and are considered joint first authors.
    Affiliations
    Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA

    Department of Anaesthesiology, Harvard Medical School, Boston, MA, USA
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  • Author Footnotes
    † Both authors contributed equally to the manuscript and are considered joint first authors.
    J.M. Peyton
    Correspondence
    Corresponding author
    Footnotes
    † Both authors contributed equally to the manuscript and are considered joint first authors.
    Affiliations
    Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA

    Department of Anaesthesiology, Harvard Medical School, Boston, MA, USA
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  • J.E. Fiadjoe
    Affiliations
    Department of Anesthesiology and Critical Care, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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  • A.I. Hunyady
    Affiliations
    Department of Anesthesiology and Pain Medicine, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, WA, USA
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  • T. Kimball
    Affiliations
    Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA
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  • D. Zurakowski
    Affiliations
    Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA

    Department of Anaesthesiology, Harvard Medical School, Boston, MA, USA
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  • Author Footnotes
    ‡ PeDI Collaborative Investigators are listed in Appendix.
    P.G. Kovatsis
    Footnotes
    ‡ PeDI Collaborative Investigators are listed in Appendix.
    Affiliations
    Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA

    Department of Anaesthesiology, Harvard Medical School, Boston, MA, USA
    Search for articles by this author
  • for the PeDI Collaborative Investigators
  • Author Footnotes
    † Both authors contributed equally to the manuscript and are considered joint first authors.
    ‡ PeDI Collaborative Investigators are listed in Appendix.

      Abstract

      Background

      We analysed data from the Paediatric Difficult Intubation Registry examining the use of direct laryngoscopy and GlideScope® videolaryngoscopy.

      Methods

      Data collected by a multicentre, paediatric difficult intubation registry from 1295 patients were analysed. Rates of success and complications between direct laryngoscopy and GlideScope videolaryngoscopy were analysed.

      Results

      Initial (464/877 = 53% vs 33/828 = 4%, Z-test = 22.2, P < 0.001) and eventual (720/877 = 82% vs. 174/828 = 21%, Z-test = 25.2, P < 0.001) success rates for GlideScope were significantly higher than direct laryngoscopy. Children weighing <10 kg had lower success rates with the GlideScope than the group as a whole. There were no differences in complication rates per attempt between direct laryngoscopy and GlideScope. The direct laryngoscopy group had more complications associated with the greater number of attempts needed to intubate. There were no increased risks of hypoxia or trauma with GlideScope use. Each additional attempt at intubation with either device resulted in a two-fold increase in complications (odds ratio: 2.0, 95% confidence interval: 1.5–2.5, P < 0.001).

      Conclusions

      During difficult tracheal intubation in children, direct laryngoscopy is an overly used technique with a low chance of success. GlideScope use was associated with a higher chance of success with no increased risk of complications. GlideScope use in children with difficult tracheal intubation has a lower success rate than in adults with difficult tracheal intubation. Children weighing less than 10 kilograms had lower success rates with either device. Attempts should be minimized with either device to decrease complications.
      Editor's key points
      • Efficacy of the use of a direct laryngoscope or a videolaryngoscope (Glidescope) was assessed, in 1295 children who were anticipated, or were discovered on initial attempt at direct laryngoscopy, to be difficult to intubate.
      • The success rate of tracheal intubation using a direct laryngoscope was quite low.
      • The Glidescope provided a higher success rate of tracheal intubation, but the success rate of intubation at the first attempt was not low (merely approximately 50%), in particular, in children weighing<10 kg.
      Multiple studies have demonstrated significant morbidity and mortality related to repeated intubation attempts and intubation failure.
      • Mort TC
      Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts.
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      In an analysis of airway management complications in children with difficult tracheal intubation, significant hypoxia occurred in 9% and cardiac arrest in nearly 2% of patients.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      Identifying techniques that have high levels of first pass success can reduce intubation attempts and may decrease life-threatening complications.
      Many different techniques are used to intubate the trachea. Direct laryngoscopy is the most commonly used technique chosen to perform tracheal intubation in children. Direct laryngoscopy was the initial technique used for tracheal intubation in nearly half the patients in a 2016 study of children who experienced difficult tracheal intubation.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      Direct laryngoscopy was also the technique of choice in nearly 90% of tracheal intubations in a study published in 2017 analysing airway management in paediatric intensive care units (PICU).
      • Grunwell JR
      • Kamat PP
      • Miksa M
      • et al.
      Trend and outcomes of video laryngoscope use across PICUs.
      However, limited information is available on the efficacy of direct laryngoscopy in children with difficult airways. In children with difficult tracheal intubation, first attempt success rates as low as 3% have been reported when direct laryngoscopy is used.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      This demonstrates the need for further studies examining the continued use of direct laryngoscopy in paediatric difficult airways.
      Videolaryngoscopy is an alternative tracheal intubation technique to direct laryngoscopy. When used as a rescue device after failed direct laryngoscopy in adults, videolaryngoscopy results in successful intubation rates exceeding 90%.
      • Jungbauer A
      • Schumann M
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      • Borgers A
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      Expected difficult tracheal intubation: a prospective comparison of direct laryngoscopy and video laryngoscopy in 200 patients.
      • Mosier JM
      • Whitmore SP
      • Bloom JW
      • et al.
      Video laryngoscopy improves intubation success and reduces esophageal intubations compared to direct laryngoscopy in the medical intensive care unit.
      • Aziz MF
      • Dillman D
      • Fu R
      • Brambrink AM
      Comparative effectiveness of the C-MAC video laryngoscope versus direct laryngoscopy in the setting of the predicted difficult airway.
      • Aziz MF
      • Healy D
      • Kheterpal S
      • Fu RF
      • Dillman D
      • Brambrink AM
      Routine clinical practice effectiveness of the Glidescope in difficult airway management: an analysis of 2,004 Glidescope intubations, complications, and failures from two institutions.
      • Aziz MF
      • Brambrink AM
      • Healy DW
      • et al.
      Success of intubation rescue techniques after failed direct laryngoscopy in adults: a retrospective comparative analysis from the multicenter perioperative outcomes group.
      Unfortunately, data regarding the use of videolaryngoscopy in children is limited and the heterogeneity between existing studies creates difficulty in interpreting their findings. In the general paediatric population, videolaryngoscopy may improve glottic visualization,
      • Armstrong J
      • John J
      • Karsli C
      A comparison between the GlideScope Video Laryngoscope and direct laryngoscope in paediatric patients with difficult airways—a pilot study.
      • Kim JT
      • Na HS
      • Bae JY
      • et al.
      GlideScope video laryngoscope: a randomized clinical trial in 203 paediatric patients.
      • Sun Y
      • Lu Y
      • Huang Y
      • Jiang H
      Pediatric video laryngoscope versus direct laryngoscope: a meta-analysis of randomized controlled trials.
      but may not increase intubation success rates when compared with direct laryngoscopy.
      • Cooper RM
      • Pacey JA
      • Bishop MJ
      • McCluskey SA
      Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients.
      • White M
      • Weale N
      • Nolan J
      • Sale S
      • Bayley G
      Comparison of the Cobalt Glidescope video laryngoscope with conventional laryngoscopy in simulated normal and difficult infant airways.
      • Fonte M
      • Oulego-Erroz I
      • Nadkarni L
      • Sanchez-Santos L
      • Iglesias VA
      • Rodriguez NA
      A randomized comparison of the GlideScope videolaryngoscope to the standard laryngoscopy for intubation by pediatric residents in simulated easy and difficult infant airway scenarios.
      A 2017 Cochrane review of videolaryngoscopy in children suggested that videolaryngoscopy ‘leads to prolonged intubation time with an increased rate of intubation failure when compared with direct laryngoscopy’.
      • Abdelgadir IS
      • Phillips RS
      • Singh D
      • Moncreiff MP
      • Lumsden JL
      Videolaryngoscopy versus direct laryngoscopy for tracheal intubation in children (excluding neonates).
      Two small studies in children with difficult intubations have demonstrated an improved view of the larynx with videolaryngoscopy but no increase in rates of intubation success,
      • Armstrong J
      • John J
      • Karsli C
      A comparison between the GlideScope Video Laryngoscope and direct laryngoscope in paediatric patients with difficult airways—a pilot study.
      • Lee JH
      • Park YH
      • Byon HJ
      • et al.
      A comparative trial of the GlideScope(R) video laryngoscope to direct laryngoscope in children with difficult direct laryngoscopy and an evaluation of the effect of blade size.
      whilst a recent study looking at a small number of children predicted to have difficult airways demonstrated an improved glottic view and high levels of successful intubation using the GlideScope® videolaryngoscopy compared with direct laryngoscopy.
      • Sola C
      • Saour AC
      • Macq C
      • Bringuier S
      • Raux O
      • Dadure C
      Children with challenging airways: What about GlideScope(R) video-laryngoscopy?.
      A large multinational study of videolaryngoscopy vs direct laryngoscopy use in PICU demonstrated that videolaryngoscopy is associated with a lower occurrence of complications, but did not show any difference in success rates or number of attempts in either group.
      • Grunwell JR
      • Kamat PP
      • Miksa M
      • et al.
      Trend and outcomes of video laryngoscope use across PICUs.
      Another recent Cochrane review comparing videolaryngoscopy vs direct laryngoscopy in neonates concluded that there is not enough evidence to recommend videolaryngoscopy in neonates.
      • Lingappan K
      • Arnold JL
      • Shaw TL
      • Fernandes CJ
      • Pammi M
      Videolaryngoscopy versus direct laryngoscopy for tracheal intubation in neonates.
      The Paediatric Difficult Intubation Registry (PeDI-R) collects data on children who experience difficult tracheal intubation. To date, two studies have been published using data derived from the PeDI-R. The first detailed the formation and structure of the registry, and offered a general overview of the complications occurring during intubation.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      The second examined the comparative success rates of videolaryngoscopy vs intubation using fibreoptic bronchoscopy through a supraglottic airway device.
      • Burjek NE
      • Nishisaki A
      • Fiadjoe JE
      • et al.
      Videolaryngoscopy versus fiber-optic intubation through a supraglottic airway in children with a difficult airway: an analysis from the multicenter pediatric difficult intubation registry.
      These studies also revealed children weighing less than 10 kilograms (kg) or less than one yr of age had lower success rates and more complications.
      We focused our analysis on the two most common techniques utilized in the PeDI-R, direct laryngoscopy and GlideScope videolaryngoscopy. We designed an a priori analysis to examine our primary aims of comparative success and complication rates between direct laryngoscopy and GlideScope videolaryngoscopy within the database. We hypothesize that the GlideScope is associated with a higher success rate and an equal or lower complication rate than direct laryngoscopy in children with difficult tracheal intubation. As secondary aims, we evaluated the effect of weight on intubation success and the success of direct laryngoscopy with poor visualization of the laryngeal inlet.

      Methods

       Study design

      The PeDI-R is a collaborative, multicentre registry, created under the auspices of the Society for Paediatric Anaesthesia to collect prospective, non-randomized, observational data on the airway management of children who meet specific criteria for difficult intubation.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      Our study included data from 20 hospitals in the United States, Canada, Mexico and Australia on attempts at intubation using either direct laryngoscopy or the GlideScope, from August 2012 through April 2017. The following categories of direct laryngoscopy blades were included for analysis: Miller, Mac, Wis-Hipple and “other blade”. When used by anaesthetists the “other blade’ category was included in our overall direct laryngoscopy analysis. Each centre's Institutional Review Board granted approval for the collection of data with the requirement for written informed consent waived. The inclusion criteria for this cohort were as follows:
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      Children under 18 yr of age, intubation attempts supervised or performed by an attending anaesthetist, difficult intubation as defined by one of the following 4 criteria:
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      • 1.
        Children with difficult laryngeal exposure as directly assessed by the attending anaesthetist with direct laryngoscopy (Cormack and Lehane Classification ≥ 3).
        • Cormack RS
        • Lehane J
        Difficult tracheal intubation in obstetrics.
      • 2.
        Children in whom direct laryngoscopy was physically impossible because of anatomical reasons (e.g. severely limited mouth opening).
      • 3.
        Children who had failed direct laryngoscopy within the preceding six months.
      • 4.
        Children in whom the attending anaesthetist deferred direct laryngoscopy as a result of a perceived poor chance of success.
      We used the following definitions:
      Initial Success: The number of patients on which the technique was initially successful divided by the number of initial attempts with the technique.
      Eventual Success: The number of patients on which the technique was successful divided by the number of patients where the technique was used.
      Complications: In the PeDI-R, complications are modified from the National Emergency Airway Registry for Children (NEAR4KIDS) operational definitions.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      • Graciano AL
      • Tamburro R
      • Thompson AE
      • Fiadjoe J
      • Nadkarni VM
      • Nishisaki A
      Incidence and associated factors of difficult tracheal intubations in pediatric ICUs: a report from National Emergency Airway Registry for Children: NEAR4KIDS.
      • Nishisaki A
      • Turner DA
      • Brown 3rd, CA
      • et al.
      A National Emergency Airway Registry for children: landscape of tracheal intubation in 15 PICUs.
      To minimize possible confounders between the two main study devices, the dataset was stratified into two specific groups (Fig. 1):
      Figure thumbnail gr1
      Fig 1Distribution of GlideScope® videolaryngoscopy and direct laryngoscopy patients from the Paediatric Difficult Intubation Registry. GVL, GlideScope® videolaryngoscope; DL, direct laryngoscopy.
      The first group consisted of 510 patients who had intubation attempts using only direct laryngoscopy or only GlideScope videolaryngoscopy: the single-device group. Univariate and multivariate analysis for the outcomes of successful intubation and complications were performed only in this group.
      The second group, the multiple-device group, consisted of 785 patients who had either: 1) direct laryngoscopy and GlideScope videolaryngoscopy attempts and possible attempts with another device; or 2) direct laryngoscopy or GlideScope videolaryngoscopy attempts and attempts with another device. For the direct laryngoscopy and GlideScope subgroup, the likelihood of GlideScope videolaryngoscopy rescue for patients who had preceding direct laryngoscopy failure was compared with that of direct laryngoscopy rescue in patients who had preceding GlideScope videolaryngoscopy failure. The initial and eventual success of other devices used in the study group was documented for comparison.
      As patient weight of less than 10 kg has correlated with increased complications and decreased success rates,
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      we compared eventual success among patients less than 10 kg with that of patients of all weights.
      We also examined direct laryngoscopy success stratified according to Cormack-Lehane view and the rate of direct laryngoscopy success given a Cormack-Lehane grade 3 view.

       Complications

      As a temporal relationship was not documented between a complication and device used, and therefore, no means to discern which device was associated with the complication when multiple devices were used, only complication data from the single-device group were analysed.

       Statistical analysis

      Logistic regression with generalized estimating equations was applied to account for correlated data because of multiple intubation attempts within the same patient.
      • Thomas RG
      • Conlon M
      Sample size determination based on Fisher's Exact Test for use in 2 × 2 comparative trials with low event rates.
      Among patients intubated in the single-device group, age and body weight were compared using the Mann-Whitney U-test and presented as medians and interquartile ranges. To compare initial and eventual success in the single-device group, multivariable logistic regression was utilized to compute odds ratios adjusted for age, body weight, ASA class, abnormal exam and anticipated difficulty as baseline covariates.
      • Levitan RM
      • Heitz JW
      • Sweeney M
      • Cooper RM
      The complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices.
      Patients having attempts with both direct laryngoscopy and GlideScope videolaryngoscopy in the multiple-device group, McNemar's test of binary matched pairs was used. Fisher's exact test was used to compare complication rates. Success rates were compared between direct laryngoscopy and GlideScope videolaryngoscopy using the Z-test for binomial proportions and 95% confidence intervals (CI) were calculated by Wilson's method.
      • Malik AM
      • Frogel JK
      Anterior tonsillar pillar perforation during GlideScope video laryngoscopy.
      Statistical analysis was conducted with IBM SPSS software (version 23.0, IBM, Armonk, NY). Two-tailed P<0.05 were considered statistically significant. Sample sizes of direct laryngoscopy (n=140) or GlideScope videolaryngoscopy (n=370) provided 90% power to detect 20% difference in initial success using Fisher's exact test.
      • Thomas RG
      • Conlon M
      Sample size determination based on Fisher's Exact Test for use in 2 × 2 comparative trials with low event rates.

      Results

      We collected data from 2294 patients, of which 1295 met our inclusion criteria. Direct laryngoscopy was used in 828 patients with 1731 intubation attempts and GlideScope videolaryngoscopy was used in 877 patients with 1364 intubation attempts.

       Success rates

      Overall, 10.2% of direct laryngoscopy attempts (176/1731) and 52.5% of GlideScope videolaryngoscopy attempts (716/1364) were successful (Z-test=25.81, P<0.001). The difference between the rates is 42% (95% CI: 39%–45%). Initial and eventual success rates per patient in which GlideScope videolaryngoscopy (n=877) or direct laryngoscopy (n=828) were attempted are shown in Figure 2. There was a significantly higher initial success rate for GlideScope videolaryngoscopy than direct laryngoscopy (464/877=53% vs. 33/828=4%, Z-test=22.2, P<0.001) with a difference in the rates of 49% (95% CI: 45%–52%). There was a significantly higher eventual success rate for GlideScope videolaryngoscopy than direct laryngoscopy (720/877=82% vs. 174/828=21%, Z-test=25.2, P<0.001) with a difference in the rates of 61% (95% CI: 57%–65%).
      Figure thumbnail gr2
      Fig 2Initial and eventual success for GlideScope® videolaryngoscopy and direct laryngoscopy for all patients and patients less than 10 kilograms. *Statistically significant. For all patients and also for patients less than 10 kg, GVL had significantly higher initial and eventual success rates than DL. For patients less than 10 kg, GVL had significantly lower initial and eventual success rates than for all GVL patients. Rates of intubation success did not differ significantly between DL patients less than 10 kg and all DL patients. GVL, GlideScope® videolaryngoscope; DL, direct laryngoscopy.
      GlideScope patients weighing less than 10 kg had significantly lower initial and eventual success rates than all GlideScope patients (Fig. 2). For GlideScope patients weighing less than 10 kg, the likelihood of successful intubation in the setting of a Cormack-Lehane grade 1 or 2a views while using the GlideScope was 53% compared with 64% for all GlideScope patients (P<0.0002).
      In the single-device group, initial success rates were 66% (244/370) for GlideScope videolaryngoscopy and 16% (23/140) for direct laryngoscopy (Z-test=10.1, P<0.001) with a difference in the success rates of 50% (95% CI: 40%–57%). Logistic regression analysis of the single-device group indicated that the unadjusted odds of initial success are estimated to be 10 times higher using GlideScope videolaryngoscopy compared with direct laryngoscopy (OR 10.0, 95% CI: 6.0–16.1, P<0.001). Given differences in patient characteristics for the single-device groups (Table 1), a multivariable logistic regression analysis was performed to adjust for baseline covariates including age, body weight, ASA classification, abnormal exam and anticipated airway difficulty (Table 2). The odds of initial success are still over seven times higher with GlideScope videolaryngoscopy compared with direct laryngoscopy (OR 7.9; 95% CI: 4.2–14.7, P<0.001) after covariate adjustment.
      Table 1Patient characteristics and rates of successful intubation based on GlideScope® videolaryngoscope or direct laryngoscopy in the single-device group. Body weight and number of attempts are reported as median (IQR). *Statistically significant. Logistic regression analysis indicated that the unadjusted odds of initial success are estimated to be 10 times higher using a GlideScope® (GVL) compared with direct laryngoscopy (DL) (OR 10.0, 95% CI: 6.0–16.1, P < 0.001). Adjusting for age, body weight, ASA class, abnormal exam and anticipated difficulty using multivariable analysis, the odds of initial success are still over seven times higher with GVL compared with DL (OR 7.9; 95% CI: 4.2–14.7, P < 0.001)
      VariableGlideScope® videolaryngoscope (N = 370)Direct laryngoscopy (N = 140)P value
      Age, yr8.1 (1.9–12.8)2.1 (0.3–9.5)<0.001*
      Body Weight, kg22.5 (11.8–35.3)11.5 (5.5–29.2)<0.001*
      Gender0.312
       Male (%)216 (58)89 (64)
       Female (%)154 (42)51 (36)
      ASA Class physical status0.137
       I–II (%)86 (23)42 (30)
       III–IV (%)284 (77)98 (70)
      Use of neuromuscular blocking agent (%)179 (48)71 (51)0.692
      Abnormal Exam (%)340 (92)92 (66)<0.001*
      Anticipated Difficulty (%)350 (95)47 (34)<0.001*
      Number of Attempts1 (1–2)3 (2–4)<0.001*
      Initial Success (%)244 (66)23 (16)<0.001*
      Eventual Success (%)370 (100)140 (100)1.000
      Table 2Multivariable logistic regression analysis – predictors of initial success at intubation in the single-device group. *Method of intubation was demonstrated to be the only significant predictor of outcome with odds of initial success over seven times higher with GlideScope® videolaryngoscope compared with direct laryngoscopy, independent of age, body weight, ASA class, abnormal exam, and anticipated airway difficulty
      VariableAdjusted odds ratio95% confidence intervalP value
      Age, yr0.980.92–1.040.521
      Body weight, kg1.010.99–1.030.136
      ASA Class Physical status1.020.64–1.610.948
      Abnormal Exam1.260.68–2.340.469
      Anticipated difficulty1.280.66–2.520.464
      Method of intubation7.854.19–14.70<0.001*
      Initial and eventual success rates in the multiple-device group are shown in Table 4 which includes the 22 other techniques used. GlideScope videolaryngoscopy was eventually successful in 68% while direct laryngoscopy was eventually successful in 5% of patients. The other 22 techniques had a 51% eventual success rate.
      Table 4Rates of successful intubation for devices utilized in the multiple device group
      Intubation devices and techniquesNumber of attemptsNumber of patientsInitial success% Initial successEventual success% Eventual success
      Direct Laryngoscopy (Anaesthesia)134868881%365%
      GlideScope® Videolaryngoscope80250721943%34668%
      Flexible Fiberoptic Bronchoscope2681667746%11770%
      Flexible Fiberoptic Bronchoscope Through a Laryngeal Mask139914752%6673%
      STORZ C-MAC® Videolaryngoscope108844958%6375%
      GlideScope® in Combination with Fiberoptic Bronchoscope65482960%3981%
      McGRATH™ MAC Videolaryngoscope42341750%2265%
      Other Device40311445%1961%
      Truview Videolaryngoscope3121943%1467%
      Airtraq Videolaryngoscope1311545%545%
      Direct Laryngoscopy with an Optical Stylet in Combination7300%00%
      Direct Laryngoscopy and Fiberoptic Bronchoscopy in Combination65360%360%
      Direct Laryngoscopy with a Lighted Stylet in Combination42150%2100%
      Blind Intubation42150%150%
      Lighted Stylet33267%267%
      Tracheostomy32150%2100%
      Blind Intubation Through a Supraglottic Airway222100%2100%
      Bonfils Optical Stylet2100%1100%
      Optical Stylet Through a Supraglottic Airway1100%00%
      Otolaryngology Techniques (ORL)94724056%4563%
      Rigid Bronchoscope2919947%1263%
      Direct Laryngoscopy and RigidBronchoscopy in Combination29241979%2188%
       Direct Laryngoscopy Other Blade (ORL)2723835%835%
      Anterior Commissure Scope96467%467%
      Of the 410 patients in the multiple-device crossover subgroup in which both GlideScope videolaryngoscopy and direct laryngoscopy were used, eventual success was achieved with either device in 339 (83%). In these 339, GlideScope was successful in 319 (94%) and direct laryngoscopy in 20 (6%), indicating a significantly higher likelihood of eventual success with GlideScope videolaryngoscopy after failed direct laryngoscopy than vice versa (P<0.001, McNemar's test for binary matched pairs). The relative success rate was over 15 times higher when using GlideScope videolaryngoscopy after direct laryngoscopy failure compared with using direct laryngoscopy after GlideScope failure.
      Of the 176 direct laryngoscopy successes from all groups, 136 (77%) were accomplished by a “blind passage” of the tracheal tube (ETT) with a documented Cormack-Lehane grade 3 or 4 view. Thirty-eight successes had grade 2 b or better view (33 grade 2 b views, three grade 2a views and two grade 1 views), but were included in the registry on account of a prior Cormack-Lehane grade 3 or 4 view on direct laryngoscopy by an Attending Anesthesiologist during the case. In the remaining two successful direct laryngoscopy, Cormack-Lehane view was not documented. Of the 881 documented Cormack-Lehane grade 3 direct laryngoscopy views, successful intubation occurred in only 13.6% (120).

       Complications

      Complication data were compiled for the single-device group where only a single device (GlideScope videolaryngoscopy or direct laryngoscopy) was used (Table 3). Univariate analysis by Fisher's exact test showed a higher rate of oesophageal intubation with direct laryngoscopy (4.3% vs 0.8%, P=0.015). In addition, the incidence of any complication among the fourteen listed in Table 3 was higher in the direct laryngoscopy group (20% vs 9.5%, P=0.002). However, patients in the direct laryngoscopy group were younger and smaller in weight and were exposed to a greater number of attempts than patients in the GlideScope videolaryngoscopy group. We performed multivariable logistic regression to assess whether the risk of oesophageal intubation or any complication differed between GlideScope videolaryngoscopy and direct laryngoscopy groups after adjusting for age, weight, number of attempts and anticipated difficulty as covariates which revealed no significant difference between the two device groups (P=0.836). This demonstrated that the difference in the rates of any complication is associated with the number of device attempts, not the specific device used, where the odds of any complication increase two-fold with every additional attempt (odds ratio: 2.0, 95% confidence interval: 1.5–2.5, P<0.001).
      Table 3Observed incidence of complications using GlideScope® videolaryngoscope or direct laryngoscopy in the single-device group. *Statistically significant, Fisher's exact test. Mutivariable logistic regression to assess whether the risk of oesophageal intubation or any complication differed between GVL and DL groups after adjusting for age, weight, number of attempts and anticipated difficulty as covariates revealed no significant difference between the two device groups (P = 0.836). This demonstrated that the difference in the rates of any complication is associated with the number of device attempts, not the specific device used, where the odds of any complication increase two-fold with every additional attempt (odds ratio: 2.0, 95% confidence interval: 1.5–2.5, P < 0.001)
      VariableGlideScope® videolaryngoscope (N = 370) (%)Direct Laryngoscopy (N = 140) (%)P value
      Vomiting2 (0.5)1 (0.7)1.000
      Epistaxis (nose bleed)3 (0.8)0 (0)0.565
      Aspiration0 (0)0 (0)1.000
      Laryngospasm6 (1.6)3 (2.1)0.711
      Bronchospasm0 (0)2 (1.4)0.075
      Oesophageal Intubation3 (0.8)6 (4.3)0.015*
      Pharyngeal Bleeding5 (1.4)0 (0)0.329
      Hypoxia18 (4.9)12 (8.6)0.139
      Cardiac Arrest1 (0.3)0 (0)1.000
      Minor Trauma9 (2.4)6 (4.3)0.256
      Major Trauma2 (0.5)1 (0.7)1.000
      Pneumothorax0 (0)0 (0)1.000
      Arrhythmia0 (0)0 (0)1.000
      Death0 (0)1 (0.7)0.275
      Any above Complication35 (9.5)28 (20.0)0.002*

      Discussion

      This is the largest study to date describing direct laryngoscopy and GlideScope videolaryngoscopy use during difficult tracheal intubation in children. GlideScope videolaryngoscopy showed superior efficacy when compared with direct laryngoscopy. Direct laryngoscopy revealing a Cormack and Lehane grade 3 or 4 view had a low eventual success rate of 21% when the anaesthesia team continued with the technique. This suggests persisting with direct laryngoscopy when these views are obtained is a poor choice. Although GlideScope videolaryngoscopy performed significantly better than direct laryngoscopy, it's success rate in children was much lower than in adults,
      • Aziz MF
      • Brambrink AM
      • Healy DW
      • et al.
      Success of intubation rescue techniques after failed direct laryngoscopy in adults: a retrospective comparative analysis from the multicenter perioperative outcomes group.
      particularly in children weighing less than 10 kg. This emphasizes the advanced consideration of alternative techniques and rescue plans should GlideScope videolaryngoscopy fail. Analysis of complications showed no demonstrable differences between devices; specifically, the use of GlideScope videolaryngoscopy was not associated with an increased incidence of hypoxia or laryngeal trauma.
      Our data show initial success with direct laryngoscopy was only 4%, compared with 53% with GlideScope videolaryngoscopy. Controlling for factors that may have influenced this result using logistic regression in the single-device group, a significant difference in success rates favouring GlideScope videolaryngoscopy persisted (Table 1). Morbidity and mortality associated with intubation are related to the number of attempts.
      • Mort TC
      Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      Multiple attempts with either direct laryngoscopy or GlideScope videolaryngoscopy increased the risk of complications and each additional attempt increased complications two-fold. Therefore, utilizing a technique with a higher first attempt success rate in these high-risk patients would be expected to decrease complications.
      In addition, in the multiple-device group where both devices were used in the same patient, GlideScope videolaryngoscopy was significantly more successful as a rescue technique for failed direct laryngoscopy than direct laryngoscopy for failed GlideScope videolaryngoscopy. Examining direct laryngoscopy successes in all groups, intubation was accomplished with a “blind passage” in 77% of patients. Though practitioners may claim efficacy with converting direct laryngoscopy Cormack-Lehane grade 3 views to successful intubations, our data reveals that successful intubation occurred in only 120 (13.6%) of the 881 grade 3 views. The extremely low success rate of direct laryngoscopy when the laryngeal inlet is not viewed indicates that clinicians should abandon prolonged direct laryngoscopy attempts, avoid repetitive direct laryngoscopy and not use direct laryngoscopy as a rescue technique. In these scenarios, an advanced intubation technique should be utilized if proceeding with intubation is deemed appropriate. If direct laryngoscopy is used to confirm the Cormack-Lehane view, a more prudent course is to have an experienced provider attempt the initial direct laryngoscopy and if confirmed, move to an alternate technique with a goal of minimizing overall attempts.
      Previous studies have demonstrated an improved laryngeal view with GlideScope videolaryngoscopy,
      • Armstrong J
      • John J
      • Karsli C
      A comparison between the GlideScope Video Laryngoscope and direct laryngoscope in paediatric patients with difficult airways—a pilot study.
      • Kim JT
      • Na HS
      • Bae JY
      • et al.
      GlideScope video laryngoscope: a randomized clinical trial in 203 paediatric patients.
      • Sola C
      • Saour AC
      • Macq C
      • Bringuier S
      • Raux O
      • Dadure C
      Children with challenging airways: What about GlideScope(R) video-laryngoscopy?.
      but with increased intubation times.
      • Jungbauer A
      • Schumann M
      • Brunkhorst V
      • Borgers A
      • Groeben H
      Expected difficult tracheal intubation: a prospective comparison of direct laryngoscopy and video laryngoscopy in 200 patients.
      • Aziz MF
      • Dillman D
      • Fu R
      • Brambrink AM
      Comparative effectiveness of the C-MAC video laryngoscope versus direct laryngoscopy in the setting of the predicted difficult airway.
      • Armstrong J
      • John J
      • Karsli C
      A comparison between the GlideScope Video Laryngoscope and direct laryngoscope in paediatric patients with difficult airways—a pilot study.
      • Kim JT
      • Na HS
      • Bae JY
      • et al.
      GlideScope video laryngoscope: a randomized clinical trial in 203 paediatric patients.
      • Sun Y
      • Lu Y
      • Huang Y
      • Jiang H
      Pediatric video laryngoscope versus direct laryngoscope: a meta-analysis of randomized controlled trials.
      • Abdelgadir IS
      • Phillips RS
      • Singh D
      • Moncreiff MP
      • Lumsden JL
      Videolaryngoscopy versus direct laryngoscopy for tracheal intubation in children (excluding neonates).
      Given the faster metabolic rates and higher rate of oxygen consumption in children, this creates a concern that the extra time taken may expose these patients, particularly those who are unwell, to an increased risk of hypoxia during intubation with the GlideScope.
      • Fiadjoe JE
      • Nishisaki A
      • Jagannathan N
      • et al.
      Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis.
      Our data did not demonstrate significant differences in the rates of hypoxia between GlideScope videolaryngoscopy and direct laryngoscopy.
      There have also been reports of significant laryngeal trauma associated with Glidescope videolaryngoscopy, which may be as a result of blind spots within the camera's field of view.
      • Levitan RM
      • Heitz JW
      • Sweeney M
      • Cooper RM
      The complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices.
      • Malik AM
      • Frogel JK
      Anterior tonsillar pillar perforation during GlideScope video laryngoscopy.
      • Magboul MM
      • Joel S
      The video laryngoscopes blind spots and possible lingual nerve injury by the Gliderite rigid stylet–case presentation and review of literature.
      • Cross P
      • Cytryn J
      • Cheng KK
      Perforation of the soft palate using the GlideScope videolaryngoscope.
      • Leong WL
      • Lim Y
      • Sia AT
      Palatopharyngeal wall perforation during Glidescope intubation.
      Children require a downsized video apparatus potentially increasing these blind spots, leading to higher rates of trauma. Our data did not demonstrate any increased risk of airway trauma, oesophageal intubation or cardiac arrest in GlideScope videolaryngoscopy compared with direct laryngoscopy.
      Even when a favourable laryngeal view was obtained, the less than 10 kg patients had significantly lower successful intubation rates. This, in part, may be explained by the anterior laryngeal tilt of the infant and toddler larynx, which would increase the likelihood of the ETT tip abutting the anterior larynx orthogonally making it difficult to pass.
      • Fiadjoe JE
      • Kovatsis P
      Videolaryngoscopes in pediatric anesthesia: what's new?.
      Other causes of lower success rates are likely multifactorial and may include inappropriate blade selection or ETT size and difficulties inherent in infants such as more rapid desaturation and greater technical difficulty when using the same sized device in a more limited oropharyngeal space compared with older children.
      Other intubation techniques used in the multiple-device group had comparable eventual success to that of GlideScope videolaryngoscopy (Table 4). Of note, GlideScope videolaryngoscopy in combination with flexible fibreoptic bronchoscopy had an eventual success rate of 81% compared with 68% for GlideScope alone in this group. A common issue in using GlideScope videolaryngoscopy and other hyperangulated blades is difficulty in successfully passing the ETT through the glottis despite good visualization.
      • Levitan RM
      • Heitz JW
      • Sweeney M
      • Cooper RM
      The complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices.
      Our data demonstrated that 36% of GlideScope attempts failed despite a Cormack-Lehane 1 or 2a view. Flexible fibreoptic bronchoscopy when used with GlideScope videolaryngoscopy not only provides another vantage point to view the airway, but the flexible fibreoptic bronchoscopy can also be used as a flexible stylet to aid in intubation. The greater success of this combined technique compared with GlideScope videolaryngoscopy alone underscores its potential effectiveness as an adjunct to the GlideScope.

       Limitations

      Multiple confounding factors may exist in our study including non-randomized clinical decisions on intubation approaches and rescue, and human data entry. We may have included a child who did not undergo direct laryngoscopy and may have been successfully intubated using direct laryngoscopy. In addition, the direct laryngoscopy group may have included initial direct laryngoscopy attempts for verification of a difficulty. These situations may skew the favourable result towards GlideScope. However, the GlideScope group had significantly greater number of patients with abnormal physical exam and anticipated difficulty with intubation. Furthermore, in the single-device direct laryngoscopy subgroup, the majority of patients had multiple direct laryngoscopy indicating that direct laryngoscopy was likely not performed to simply verify difficult intubation but as the chosen primary airway management technique.
      We cannot determine the experience of the providers with the use of the GlideScope videolaryngoscopy as specialized training and years of practice may not necessarily reflect adequate experience with the device. We were limited by the available patients in the registry at the time of analysis, and it is possible that the sample size was not adequate to determine small differences between groups, particularly with respect to complications. Institutional influences and recurrent intubations in the same patient were not considered in our analysis. Other confounding factors may be hidden within the dataset despite splitting the patients into two distinct groups, to control for these.
      Our study looked exclusively at the GlideScope as it was the most commonly used videolaryngoscope within the PeDI-R. There are many different videolaryngoscopes available. Some have traditional laryngoscopic blades and allow the user to perform both direct laryngoscopy and indirect videolaryngoscopy (e.g. STORZ C-MAC® and McGRATH®MAC), while others have a ‘hyperangulated’ blade which arcs around the usual curve of the airway, but are only intended for indirect visualization
      • Levitan RM
      • Heitz JW
      • Sweeney M
      • Cooper RM
      The complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices.
      (e.g. GlideScope®, McGRATH®X-Blade, UEScope® and STORZ C-MAC® D-blade). The current small number of other videolaryngoscopy devices in the PeDI-R precludes detailed comparative analysis. No definitive evidence supports the use of one individual device over another, strongly supporting the need for prospective randomized controlled trials comparing videolaryngoscopes.

      Conclusion

      Direct laryngoscopy is a poor choice for children who are anticipated, or are discovered on initial attempt at direct laryngoscopy, to be difficult to intubate. GlideScope videolaryngoscopy has significantly higher success rates than direct laryngoscopy, and was not associated with an increased risk of complications. Complication rates were associated with the number of attempts at tracheal intubation, independent of the particular device used, where the odds of any complication occurring increased two-fold with every additional attempt. Although GlideScope videolaryngoscopy performed significantly better than direct laryngoscopy, initial and eventual success rates were disappointing in these high risk paediatric patients and lower than the published adult success rates. This lower success rate was magnified in patients weighing less than 10 kg. Further studies comparing the efficacy of different videolaryngoscopes in children are needed, whilst continuing emphasis must be placed on avoiding hypoxia and decreasing repeated attempts at intubation.

      Authors contributions

      Study design/planning: J.P., R.P., J.F., A.H., D.Z., P.K.
      Study conduct: J.P., R.P., P.K., T.K.
      Data analysis: R.P., J.P., D.Z., T.K., P.K.
      Writing paper: J.P., R.P., D.Z., P.K.
      Revising paper: all authors

      Declaration of interest

      None declared.

      Funding

      Supported by internal funding from the Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA and the Department of Anesthesiology and Critical Care Medicine, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.

      Appendix

      PeDI collaborative investigators
      Department of Anesthesiology and Pain Medicine, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, Washington
      A. Bosenberg, MD
      Department of Anesthesiology, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
      P. Hopkins, MD
      C. Glover, MD, MBA
      O. Olutoye, MD
      Department of Anesthesiology and Pain Management, University of Texas Southwestern and Children's Health System of Texas, Dallas, Texas
      P. Szmuk, MD
      P. Olomu, MD
      Division of Anesthesia, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois
      N. Jagannathan, MD
      N. Burjek MD
      Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee
      S. Watkins, MD
      Department of Pediatric Anesthesiology, University of Michigan Health Center, Ann Arbor, Michigan
      P. Reynolds, MD
      B. Haydar MD
      Department of Anesthesiology, University of Texas Medical School at Houston, Houston, Texas
      M. Matuszczak, MD
      R. Jain, MD
      S. Khalil, MD
      Department of Anesthesiology, Children's Hospital of Colorado, Aurora, Colorado
      D. Polaner, MD
      J. Zieg, MD
      J. Szolnoki, MD
      Department of Anesthesiology, University of Mississippi Medical Center, Jackson, Mississippi
      M. Sathyamoorthy, MD
      Department of Anesthesiology, Duke University, Durham, North Carolina
      B. Taicher, MD
      Department of Anesthesia, Critical Care and Pain, Massachusetts General Hospital, Boston, Massachusetts
      S. Bhattacharya, MBBS
      Department of Anesthesiology and Pain Medicine, Nationwide Children's Hospital, Ohio State University, Columbus, Ohio
      V. Raman MD
      T. Bhalla, MD
      Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
      P. Stricker, MD
      J. Lockman, MD
      J. Galvez, MDM. Rehman, MD
      A. Nishisaki, MD, MSCE
      Department of Anesthesiology and Pain Management, University of Western Australia, Crawley, Australia
      B. von Ungern-Sternberg, MD
      D. Sommerfield, MD
      Department of Anesthesiology, University of New Mexico, Albuquerque, New Mexico
      C. Soneru, MD
      Department of Anesthesiology, Weill Cornell Medical College, New York, New York
      F. Chiao, MD
      Department of Anesthesiology, University of Minnesota, Minneapolis, Minnesota
      M. Richtsfeld, MD
      K. Belani, MD
      Department of Anesthesiology, National Institute of Pediatrics, Mexico City, Mexico
      L. Sarmiento, MD
      Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University Medical Center, Stanford, California
      S. Mireles, MD
      Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
      G. B. Rosas, MD.

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