Video‐laryngoscopy versus direct laryngoscopy for tracheal intubation in children (excluding neonates)
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess the safety and efficacy of optical/video laryngoscopy compared to direct laryngoscopy when used for intubation in children, with regard to: intubation time; number of attempts at intubation; changes in oxygen saturation; and adverse effects, including abnormal haemodynamic response to endotracheal intubation.
Background
Description of the condition
Tracheal intubation is a lifesaving procedure, and an important step in cardiopulmonary resuscitation, which helps in establishing an artificial airway (Zhao 2014). In the operating theatre, tracheal intubation is usually applied after anaesthesia induction to facilitate a secured airway in cases involving neuromuscular paralysis and positive pressure ventilation (Zhao 2014). A direct laryngoscope is the most widely used device to facilitate tracheal intubation (Scott 2009), but is considered difficult to apply for novice personnel; it is reported that a 90% success rate requires 47 times of intubation practice (Mulcaster 2003).
Problems with tracheal intubation were the most frequently recorded primary airway problem with difficult, delayed and failed intubation, as well as "can’t intubate can’t ventilate" scenarios (Woodall 2011). Unfortunately, physical findings on examination of the airway discriminate poorly between potentially easy and difficult intubations (Shiga 2005). Direct laryngoscopy (DL) occasionally offers unexpectedly poor laryngeal views. Such difficulty, even if ultimately overcome, may result in multiple laryngoscopic attempts and significant morbidity, such as desaturation, airway and dental injuries, and cardiac arrest leading to neurological impairment. Rarely, such incidents may cause death (Cheney 1999).
Description of the intervention
Intubation was rarely performed in children before the 1940s, by which time there had been an improvement in the understanding of childhood physiology under anaesthesia and some specialist anaesthetic equipment for children had been developed (Costarino 2005). Indirect laryngoscopy involves visualizing the person's vocal cords by a means other than obtaining a direct line of sight. There are a number of different types of indirect laryngoscope that facilitate intubation. Classic examples are fibreoptic and video laryngoscopes.
The fibreoptic laryngoscope is a single‐use device for tracheal intubation. The curvature of the blade and the special internal arrangement of the optical components allow visualization of the glottic plane without alignment of the oral, pharyngeal, and tracheal axes, which may facilitate an easier glottic exposure (Zhao 2014). The combination of the fibreoptic bronchoscope and the laryngoscope led to the development of video laryngoscopes, providing a video‐based view of the glottic opening, with or without additional guidance of the tube towards the tracheal opening (Theiler 2013). In general, these techniques offer the advantage of abandoning the need to align the optical axis in the pharynx and mouth to visualize the entrance of the larynx (Jungbauer 2009). However, it remains unclear if this translates into increased success with intubation (Griesdale 2012; White 2012).
How the intervention might work
Intubation in children is increasingly performed using optical/video laryngoscopes, and these are now emerging as important adjuncts in airway management (Fiadjoe 2012). A video camera at the tip of the blade can potentially provide an increased angle and a magnified view of the glottis in the normal and difficult paediatric airway (Vlatten 2009). Optical laryngoscopes use magnifying mirrors, a light source, and a guide to help in visualization of the vocal cords and passing the endotracheal tube. Specific to paediatric anaesthesia, it is more difficult for the trainer and learner to share the same view, and the excellent view and remote screen of the indirect laryngoscope may therefore be particularly useful (Macnair 2009).
In adults both manikin and human studies have suggested that video laryngoscopy provides superior intubating conditions and has a shorter learning curve (Vlatten 2012). Paediatric studies suggest that video laryngoscopy is equally suitable to facilitate intubation compared to direct laryngoscopy (Fiadjoe 2012; Kim 2011; Redel 2009; Vlatten 2012). A study using paramedics, medical students, respiratory therapists, and nurses in the live situation of the operating room showed that video‐laryngoscopy has higher success rates and shorter times to intubation for adults (Jungbauer 2009). Moreover, a systematic review of adult intubation using video laryngoscopy has shown some improvement in intubation outcomes (Griesdale 2012).
Why it is important to do this review
Airway management and intubation are important in both elective and emergency situations where a secure airway is required. The current practice is to use direct laryngoscopy to facilitate intubation. Optical/video laryngoscopy has the potential to facilitate successful intubation and improve intubation outcomes. Kim 2008 reported that in children, video laryngoscopy provided a laryngoscopic view equal to or better than that of direct laryngoscopy. Video laryngoscopy is easier to use by the investigators and results in a lower alteration in the heart rate (Maharaj 2006; Waleed 2012); however, to date there have been no systematic reviews to address the effects of optical/video laryngoscopy on paediatric intubation outcomes.
Our review excludes neonatal intubations, as this age group have different airway anatomy and intubation techniques. It is beyond the scope of this review to address the cost effectiveness and global health or policy‐based impact of this expensive and technology‐dependent intervention.
Objectives
To assess the safety and efficacy of optical/video laryngoscopy compared to direct laryngoscopy when used for intubation in children, with regard to: intubation time; number of attempts at intubation; changes in oxygen saturation; and adverse effects, including abnormal haemodynamic response to endotracheal intubation.
Methods
Criteria for considering studies for this review
Types of studies
We will include only randomized controlled trials (RCTs) that compare intubations of children, using either optical or video laryngoscopy, to direct laryngoscopy. We will exclude manikin and simulation studies.
Types of participants
We will include children aged 28 days to 16 years who needed intubation as an elective or emergency procedure done in the operating room.
Types of interventions
Any optical/video laryngoscope used for intubation of children compared with direct laryngoscopy. We will include all the different types of optical and video laryngoscopy devices used for intubation in children.
Types of outcome measures
Primary outcomes
-
Intubation time.
-
The number of attempts at intubation and unsuccessful intubation.
-
Adverse haemodynamic response to endotracheal intubation, including changes in: oxygen saturation, mean blood pressure, heart rate and heart rhythm.
Secondary outcomes
-
Other adverse effects of intubation in children, including trauma to oral, pharyngeal, and laryngeal structures, assessed by visual or laryngoscopic examination.
-
Vocal cord view score.
Search methods for identification of studies
Electronic searches
We will search the current issue of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (Ovid SP, 1946 to date), EMBASE (Ovid SP, 1974 to date), and CINAHL (EBSCO, 1982 to date) . See Appendix 1 for the search strategy that we will use in this review. We will adapt the search terms used in MEDLINE for the other database sources.
Searching other resources
We will search for the current unpublished ongoing clinical trials on the following websites: www.clinicaltrials.gov and www.controlledtrials. We will search relevant conference proceedings, abstracts and internal reports, and will contact authors of studies for unpublished data or studies. We will review the reference lists for other possible clinical trials and personal collections of articles if needed. We will apply no language restriction, and will undertake English translation of relevant studies if needed.
Data collection and analysis
Selection of studies
We will follow the standard methods of the Cochrane Anaesthesia Review Group. Two review authors (IA and MM) will independently assess the titles and the abstracts, and, if needed, the full text of the identified studies, for inclusion eligibility in this review. We will resolve any disagreement by consultation with a third author (JL).
Data extraction and management
We will obtain full‐text versions of all studies that may be included in the review for assessment. We will use the form provided by the Cochrane Anaesthesia Review Group for data extraction, which the review authors will do independently when we identify eligible trials (see Appendix 2). We will compare the extracted data for any differences, which we will resolve by discussion. We will enter the data into Review Manager 5 (RevMan 5.3) for further processing and analysis.
Assessment of risk of bias in included studies
Two review authors (IA and MM) will independently assess the risk of bias for each study, using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).
We will resolve any disagreement by discussion or by involving a third review author (JL). We will assess the risk of bias according to the following domains :
-
Random sequence generation (selection bias);
-
Allocation concealment (selection bias);
-
Blinding of participants and personnel (performance bias);
-
Blinding of outcome assessment (detection bias);
-
Incomplete outcome data (attrition bias);
-
Selective outcome reporting (reporting bias).
We will grade each potential risk of bias as being at low, high or unclear risk. We will detail all of the judgements made for all the included studies in the review regarding the risk of bias assessment in the 'Risk of bias' tables, which will be part of the 'Characteristics of included studies' tables.
Measures of treatment effect
We will report the risk ratio (RR) for dichotomous data.
We will calculate the mean difference (MD) or standardized mean difference (SMD) for continuous data.
Unit of analysis issues
We will assess only RCTs, with the unit of analysis being the participating child that needed intubation. We will not assess cluster‐randomized trials, cross‐over trials or studies with multiple treatment groups.
Dealing with missing data
We will contact the authors of published studies for further clarification or to provide additional information if required. We will highlight all missing data as part of the Results section. We will analyse all the randomized children on an intention‐to‐treat basis (ITT). We will discuss any drop‐out of children after randomization in the review, to address the implications and their effect on the results if applicable.
Assessment of heterogeneity
We anticipate heterogeneity of studies, due to nature of the interventions used. We will use the I² statistic (Higgins 2002) to measure heterogeneity among the trials. We will further explore this by subgroup analysis if appropriate.
Assessment of reporting biases
We will contact study authors to retrieve any missing data, if suspected. We will use a sensitivity analysis to explore the impact of including studies with missing data in the overall assessment of results (Egger 1997). If at least 10 studies contribute to an outcome, we will create a funnel plot to investigate the potential of reporting and publication biases.
Data synthesis
We will perform statistical analyses according to the recommendations of the Cochrane Anaesthesia Review Group. We will use the statistical package Review Manager 5 provided by The Cochrane Collaboration for data synthesis and analysis. We will report all measures with 95% confidence intervals (CIs). As we expect heterogeneity between studies, we will undertake meta‐analysis with a random‐effects model. We will explore the influence of predefined subgroups if enough data are available.
Subgroup analysis and investigation of heterogeneity
Planned subgroup analyses, where data are available, will be based on:
-
The degree of airway difficulty;
-
The age of the child;
-
The skill level of the operator;
-
The type of video laryngoscopy equipment used; and
-
Emergency versus elective intubation.
Sensitivity analysis
We will use sensitivity analyses to explore the potential impact of missing data and any methodological heterogeneity. If we have sufficient data, we will test the robustness of the evidence by a sensitivity analysis, omitting studies at high risk of bias from the meta‐analysis. We will assess high risk of bias according to the following domains: Random sequence generation; allocation concealment; blinding of participants and personnel; blinding of outcome assessment; incomplete outcome data and selective outcome reporting.
Summary of findings
We will use the principles of the GRADE system (Guyatt 2008) to assess the quality of the body of evidence associated with specific outcomes (reduction in the intubation time, the number of attempts at intubation, unsuccessful intubation, adverse haemodynamic response to endotracheal intubation, and improving the vocal cord view), and will construct a 'Summary of findings' (SoF) table using the GRADE software. The GRADE approach appraises the quality of a body of evidence based on the extent to which one can be confident that an estimate of effect or association reflects the item being assessed. It takes account of within‐study risk of bias (methodological quality), the directness of the evidence, the heterogeneity of the data, the precision of effect estimates, and the risk of publication bias.
