Healthcare | Free Full-Text | Comparison of UESCOPE VL 400, I-View, Non-Channeled Airtraq Videolaryngoscopes and Macintosh Laryngoscope for Tracheal Intubation in Simulated Out-of-Hospital Conditions: A Randomized Crossover Manikin Study
This study was conducted at the Norbert Barlicki University Clinical Hospital No. 1 in Lodz, Poland, from 28 February 2021 to 30 June 2021, following approval from the Medical University of Lodz Bioethics Committee (ref: RNN/363/13/KB, date: 20 February 2021). Prior to the start of recruitment, the study was registered on ClinicalTrials.gov (NCT number: NCT05946694). All participants provided informed written consent for voluntary participation. Students who met the inclusion criteria were invited to participate in the study, which included being a third-year full-time first-degree student in Emergency Medicine at the Medical University of Lodz and willing to participate after being randomly selected according to the template number. The exclusion criterion was previous clinical experience with the laryngoscopes used in the study.
This trial was a simulation-based, single-center, randomized, crossover study.
2.1. Pre-Study Preparation
All participants attended a 30 min lecture on laryngoscope construction, the principles of usage, the anatomical structure of the airways, and intubation techniques based on manufacturers’ recommendations. Following the lecture, the instructor demonstrated proper intubation using each of the four laryngoscopes that were being tested. Next, the students participated in a supervised workshop where they had the opportunity to intubate a manikin of head, neck, and lower airways placed on an operating table at an optimal height, with the manikin’s head in a neutral position, using each of the tested laryngoscopes with and without a stylet. One month later, 30 students participated in the actual study.
2.2. Simulation Model
To create simulated out-of-hospital conditions, a certified airway training manikin (Laerdal Airway Management Trainer Stavanger Norway of universal difficulty) was placed in a neutral position at the floor level.
Each participant performed eight intubations on the manikin using all four devices. The intubation order was randomized using a blocked randomization strategy generated by the Randomizer Program (randomizer.org, accessed on 14 January 2024). A sealed opaque envelope was used to determine the order in which the laryngoscopes were used and whether the tube was with or without a stylet.
After each intubation, there was a minimum 10 min pause before the next one. The subject then proceeded to the next intubation with the randomly selected laryngoscope, with the tube and stylet as determined by the sealed envelope.
All intubations were performed using a polyvinyl chloride cuffed endotracheal tube (Covidien LLC, Hampshire Street, Mansfield, MA, USA; internal diameter 7.0 mm) and an endotracheal stylet (Sumi® from sp. z o.o., 35 Drobiarska Street, 05-070 Sulejówek, Poland), when used. The endotracheal tubes and stylets were coated with a standard lubricant for simulators. All data were pseudonymized for each simulation.
Primary outcome measures were the time taken to successfully achieve tracheal intubation (TI). Secondary outcomes included the grade of glottic view (Cormack and Lehane grades 1–4), the incidence of successful TI, the number of audible dental clicks indicating potential dental damage, the level of effort required to perform TI, and the operator’s comfort during the procedure.
The time was measured by the same investigator (P.R.) using a stopwatch for all TI attempts. The timing measurement started when the participant picked up the laryngoscope and ended when initial ventilation was achieved using a resuscitation bag after the placement and sealing of the endotracheal tube. Successful TI was confirmed by observing the breathing movements of the manikin lungs. An unsuccessful attempt was defined by the absence of respiratory movements of the dummy or an intubation time of more than 60 s. This criterion was adopted because the study aimed to assess the suitability of the devices for individuals without clinical experience in intubation. Participants without sufficient skills or a good view of the glottis can prolong intubations without knowing how to solve the problem. In a real clinical scenario, such prolongation of intubation attempts beyond 60 s can result in irreversible brain damage in the victim, especially considering the necessary time for the emergency medical team to arrive.
Participants rated the level of effort required to perform TI using the modified Borg scale (0—no effort, 10—maximum effort) and graded their comfort during the procedure as “full comfort, satisfactory comfort, moderate comfort, unsatisfactory comfort, and no comfort”.
2.4. Statistical Analysis
We used Statistica 13.1PL (StatSoft, Poland, Krakow) to perform the statistical analysis.
The distribution of the continuous data was checked with the Shapiro–Wilk test. The majority of the data had a distribution other than normal (p < 0.05) or were measured on the ordinal scale. Therefore, they are further presented as the median with the interquartile range (IQR). The dependencies between them were assessed with Kruskal–Wallis’s test, Dunn’s post hoc tests for independent data, and with Wilcoxon’s test for dependent data. Nominal data are presented as n (%) and were assessed with a test chosen based on the size of the smallest subgroup: n < 5—Fisher’s exact test, 5 ≤ n < 15—Yates’s chi-squared test, and 15 < n—chi-squared test.
The sample size was calculated using the R Stats Package v4.2.2. Based on previous student training registers, we might consider 30 s to be a significant difference between means, so 30 participants might yield a type-1 error of 5% and a power of 90%.
This simulation-based, randomized, crossover study trial showed that the I-View laryngoscope proved to be the best-rated laryngoscope in our study, with respect to the primary and secondary endpoints of the study. It showed a 100% success rate for intubation without a stylet and with a stylet, the fastest intubation times in both cases being, respectively: 16.6 s vs. 20.3 s. It is the only laryngoscope in our study that showed shorter intubation times without a stylet than with one. For secondary endpoints, it also proved to be similar to the UESCOPE in terms of comfort and intubation effort. The percentage of tooth damage in our study was 13.3% regardless of whether we used a stylet or not. In the absence of a stylet, this percentage was the same as for the least-traumatic laryngoscope in our study, which was the UESCOPE VL 400. In the situation of using a stylet, the UESCOPE VL 400 and Airtraq laryngoscopes, where the percentage of tooth damage was 3.3% and 6.6%, respectively, proved to be the safer devices. In the case of this laryngoscope, the use of a stylet statistically significantly increased the comfort of intubation compared to the variant without a stylet, resulting in a lack of negative evaluations associated with its use. This laryngoscope had the best view of the glottis according to the Cormack–Lehane scale.
In our study, for the UESCOPE VL 400 laryngoscope, the use of a stylet resulted in an increase in the percentage of successful intubations from 96.6% in the situation without a stylet to 100% when one was used. This laryngoscope, like the I-View laryngoscope, had an intubation success rate of 100% when a stylet was used. The average intubation times were slightly longer than those of the I-View laryngoscope i.e., 23.4 s and 18.1 s for the no-stylet and stylet scenarios, respectively, statistically significantly reducing this time. The use of this laryngoscope was associated with the same intubation effort as the I-View laryngoscope in the absence of a stylet and slightly less when a stylet was used. The use of a stylet with this laryngoscope statistically significantly increased the intubation comfort compared to the variant without a stylet. In the case of the UESCOPE VL 400 laryngoscope, the use of the stylet resulted in a reduction in the percentage of tooth damage from 13.3% to 3.3%. The glottis visibility obtained with this laryngoscope was only slightly worse than that obtained when using the I-View laryngoscope.
In our study, the data obtained put the UESCOPE VL-400 laryngoscope on a par with the I-View laryngoscope and were better than the results of the Airtraq video laryngoscope and the reference Macintosh laryngoscope.
For the Airtraq laryngoscope, the use of a stylet led to an increase in the percentage of successful intubation from 86.67% to 100% and a statistically significant decrease in intubation time from 34.52 s to 22.75 s. Compared to the other laryngoscopes used in the study, the average intubation times were the longest for the Airtraq laryngoscope for both the scenarios without and with the stylet. However, they were within acceptable values for laryngoscopes. For secondary endpoints, the use of a stylet resulted in a statistically significant reduction in the percentage of tooth damage from 26.67% to 6.67% and did not affect intubation comfort. A big difference in these statistics in comparison to other laryngoscopes may stem from the different curvature of a blade, demanding an altered intubation technique, making it much harder for inexperienced intubators to use it without a stylet. Inexperienced intubators tend to prefer learning the most-wildly used Macintosh-type laryngoscopes and videolaryngoscopes, and any other laryngoscope requiring another technique is a difficulty for them. This laryngoscope had the highest effort required to intubate the manikin of all laryngoscopes regardless of the variant with and without the stylet. The use of the Airtraq laryngoscope did not significantly improve the visibility of the glottis compared to the other laryngoscopes included in the study.
In our study, the Macintosh laryngoscope showed the same intubation efficiency of 100% for variants with and without a stylet as the I-View video laryngoscope. However, it was inferior to it in terms of the intubation time of 24.0 s in this case vs. 16.6 s in the situation without a stylet and 21.8 s vs. 20.3 s when a stylet was used. In the case of this laryngoscope, the use of a stylet resulted in a statistically significant reduction in intubation time, better intubation comfort, and a reduction in the percentage of tooth damage from 30% to 20%. The Macintosh laryngoscope had a similar intubation effort as the use of the Airtraq laryngoscope, and it was significantly higher than when using the UESCOPE VL 400 and I-View video laryngoscopes. The Cormack–Lehane scale view of airway entry that can be obtained using the Macintosh laryngoscope was the worst of all the devices involved in our study, but there was no statistical difference.
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