Comparison of Training Effect for Tracheal Intubation Following Training With McGrath Video Laryngoscope as Direct Laryngoscope Versus Training With McGrath Video Laryngoscope as Video Laryngoscope
Phase: NA
Conditions: Airway Management, Endotracheal Intubation, Medical Education
Sponsor: Ajou University School of Medicine

Comparison of training effect for tracheal 
intubation following training with McGrath video 
laryngoscope as direct laryngoscope versus training 
with McGrath video laryngoscope as video 
laryngoscope 
 
 
 
NCT03471975 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
March 01 2018 
 

 
Brief Title: Learning Direct Laryngoscopy Using a McGrath Video Laryngoscope as Direct Versus Indirect 
Laryngoscope 
 
Official Title: Comparison of training effect for tracheal intubation following training with McGrath video 
laryngoscope as direct laryngoscope versus training with McGrath video laryngoscope as video laryngoscope 
 
Study Type: Intervention 
 
Principal Investigator: Jihoon Hwang, M.D., Ajou University School Of Medicine, kironojh@gmail.com 
 
 
Objective 
Tracheal intubation using a direct laryngoscope is an essential skill but is difficult to teach. Video laryngoscopes 
enhance the teaching ability for direct laryngoscopy and can be used with direct or indirect methods. We compared 
the effect on the skill improvement of Macintosh direct laryngoscopy following training with a McGrath video 
laryngoscope as a direct versus an indirect laryngoscope. 
 
Design 
prospective, cluster-randomized controlled trial 
 
 
Methods 
This study was a single-center, prospective, cluster-randomized controlled trial with two parallel groups that was 
carried out at Ajou University Hospital from March 2018 to July 2018. The trial was approved by the institutional 
review board of Ajou University Hospital (AJIRB-SBR-OBS-17-507, Feb 20, 2018) and was registered at 
ClinicalTrials.gov (NCT03471975). 
 
Eligible participants were medical students who are novices at direct laryngoscopy. All of the participants agreed 
to have their performances evaluated and anonymously used for scientific and educational purposes. 
 
Rotation groups (including 11 groups that each included 3–4 students) were randomly divided into one of two 
groups in ratio of 1:1 by the cluster randomization method, using a computer-generated random number table. 
The allocation process was conducted by a colleague who remained independent of this research project. The 
randomization result was concealed within serially numbered opaque envelopes, which were opened prior to 
teaching and lecture. One group was trained using direct laryngoscopy with a video laryngoscope (direct group), 
and the other group was trained using indirect (video) laryngoscopy with a video laryngoscope (indirect group). 
Cluster randomization was adopted to eliminate possible contamination between students due to individual 
randomization within each rotation.  The blinding of participants and instructors was not possible due to the nature 
of the interventions 
 
The study took place on the first day of the rotation. First, an initial evaluation of the students’ intubation skills 
was performed on a standardized manikin (Laerdal® Airway Management Trainer; Laerdal, Stavanger, Norway) 
using a Macintosh laryngoscope (Diamond range; Penlon, Abingdon, UK; Macintosh blade size 3). The instructor 
evaluated each attempt and gave no feedback. Then, a lecture on airway anatomy, evaluation, and Cormack-
Lehane classification (degree of glottis exposure), as well as airway management, was given, followed by tutorial 
videos on the technique of direct laryngoscopy and introduction of the McGrath™ MAC video laryngoscope 

(Medtronic, Minneapolis, MN, USA). Following the lecture, a teaching sequence with the McGrath™ MAC video 
laryngoscope was conducted. All participants performed five intubations in the manikin using the McGrath™ 
MAC video laryngoscope (blade size 3) with the instructor’s direct feedback. The direct group intubated using 
the video laryngoscope as a direct laryngoscope, where only the instructor could observe the video screen and 
give feedback. The indirect group used the video laryngoscope as an indirect laryngoscope, so that they shared 
the video view with the instructor and received feedback. 
Then, a final evaluation was performed in which the students performed tracheal intubation using the Macintosh 
direct laryngoscope in the same manikin in the following scenarios: 1) normal airway in the supine position and 
2) cervical immobilization with a semi-rigid foam neck collar (Philadelphia cervical collar; A-Mi Global, Busan, 
South Korea). Each student performed the intubation twice for each scenario, and the instructor evaluated each 
attempt. For all intubation attempts, a standard beveled Portex®  tracheal tube (Smiths Medical, Hythe, UK; 7.0 
mm internal diameter, 9.6 mm outer diameter) was used with a stylet inserted in the tube. The tube was bent into 
a “hockey-stick” curvature. The outcome assessors did not involve in training and were kept blinded to the 
allocation.  
 
The primary endpoint was the intubation time, defined as the time taken from insertion of the blade between the 
teeth until the cuff of the tube was inflated. Unilateral bronchial intubation was considered successful for the 
purpose of this study. A failed intubation was defined as when it was not completed within 120 seconds or it 
resulted in an esophageal intubation. Additional data obtained included the rate of successful tracheal intubation, 
dental trauma, and degree of difficulty. Dental trauma was counted based on the number of audible teeth clicks 
(0, 1, and 2) in the Laerdal airway trainer. After the students completed the attempts, they were asked to score the 
degree of difficulty using each device with a 10-point numeric rating scale (NRS; 0 = easy, 10 = difficult). 
 
 
Statistical Analysis Plan 
All statistical analyses were performed using SAS version 9.4 (SAS Institute, Inc., Cary, NC, USA).  
Data are presented as the mean and SD when normally distributed, as the median and interquartile range when 
non-normally distributed, and percentage when appropriate.  
We used the linear mixed effects model to analyze intubation times and the degree of difficulty.  
We also applied the generalized linear mixed model with binomial distribution and generalized estimating 
equations methods to analyze the intubation success rate.  
As fixed effects, we included baseline intubation time, age, sex, group, manikin, time, and time by group 
interactions.  
As random effects, we used a random intercept and slope for intubation time after education and a random 
intercept only for the degree of difficulty.  
The variance-covariance structures were chosen with the smallest Akaike Information Criterion criteria. In regard 
to the selection of working correlation matrix in the generalized estimating equations model, Quasi-likelihood 
under the Independence model Criterion was used to assess the goodness-of-fit. We also specified and partitioned 
different variance-covariance structures for each level of manikin. For comparing times before training with those 
after training, we used the paired t-test, Mann-Whitney U test, or McNemar’s test, as appropriate. A p-value < 
0.05 was considered statistically significant.