a b s t r a c t

Introduction: The aim of the study was to compare the efficacy of the TruView EVO2, TruView PCD, and Miller la- ryngoscopes for tracheal intubation during cardiopulmonary resuscitation with and without Chest compressions by paramedics in an infant manikin model.

Methods: This was an open, prospective, randomized, simulated trial. After a brief didactic session, 78 volunteer paramedics attempted to intubate a manikin using TruView EVO2, TruView PCD, and Miller laryngoscopes during resuscitation with and without CC scenarios. Primary end point was intubation success rate and secondary was time to intubation with each device. glottic view using a Cormack-Lehane grade in using each device was also assessed.

Results: In scenario with uninterrupted CCs, the median time to intubation using the TruView EVO2, TruView PCD, and Miller varied with the times being 25.3 seconds (interquartile range [IQR], 23-30.5 seconds) vs 20.2 sec- onds (IQR, 18-23 seconds) vs 24.4 seconds (IQR, 21-28 seconds), respectively. The overall success rate of intuba- tion during CC for the devices were 94.9% vs 100% vs 92.1%. During intubation without CC, median time to intubation varied and amounted to 24.9 seconds (IQR, 21-29.6 seconds) for TruView EVO2, 18.3 seconds (IQR, 16-21.3 seconds) for TruView PCD, and 19.4 seconds (IQR, 17-23.3 seconds) for Miller laryngoscope. The overall success rate of intubation without CC for all devices was 100%.

Conclusions: For infant tracheal intubation with TruView PCD, when used by paramedics, the malleable TruView PCD showed shorter intubation time and higher overall success rate in a simulated CC scenario than TruView EVO2 or Miller laryngoscopes. Further clinical studies are necessary to confirm these initial positive findings.

(C) 2015

Introduction

The main cause of cardiac arrest in pediatric patients is respiratory failure. Ensuring Adequate airway management and adequate oxygena- tion of the patient is a key element of cardiopulmonary resuscitation (CPR) [1]. European Resuscitation Council (ERC) guidelines of 2010 re- commend conducting CPR with possible shortest interruptions of Chest compressions and, for the criterion standard for airway

? Author’s contributions: Conception and design, L.S., M.M., K.K., Z.T., A.K., and L.C.; analysis and interpretation, A.K. and L.S.; drafting the manuscript for important intellectual content, L.S., M.M., K.K., Z.T., A.K., and L.C.

?? Source of support: No sources of financial and material support to be declared.

? Conflict of interest statement: The authors declare that they have no conflicts of interest.

* Corresponding author at: Department of Anesthesiology, Cardinal Wyszynski National Institute of Cardiology, Alpejska 42 Street, 04-628 Warsaw, Poland. Tel.: +48 500186225.

E-mail address: [email protected] (A. Kurowski).

control, consider Endotracheal intubation [2,3]. These guidelines also suggest that the intubator should be able to secure the airway with- out interrupting CC. During CPR, the endotracheal tube allows the use of asynchronous resuscitation, so there is no need to interrupt CCs to perform rescue breaths [2].

The efficacy of intubation using a standard Miller laryngoscope (MIL; LifeLine Medical, Inc, Brooksville, FL) or Macintosh laryngoscope during pediatric out-of-hospital intubation performed by paramedics occurred from 63.4% to 82% [4-7]. The problem of unsatisfactory efficacy of the first attempts of pediatric intubation refers not only to para- medics and activities under prehospital care. Choi et al [8] conducted a study in 13 emergency departments, which indicated that the efficacy of the first attempt of intubation with MIL performed by physicians with a specialization in emergency medicine was 74.4%, whereas, in the case of physicians with other medical specialties other than emer- gency or anesthesiology, the efficacy was only 50%. The low efficacy of

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the first attempts of intubation performed by paramedics and emergency physicians also indicates, in a trial by Ehrlich et al [9], that the efficacy of the first intubation attempt performed by paramedics was 45% and, by physicians with the specialty of emergency medicine (outside from trauma centers), 67% [9].

Because of the low efficacy of intubation using a standard direct laryngoscopy, we should look for new methods of laryngoscopy that would increase ETI efficiency.

We hypothesized that video laryngoscopes are beneficial for intuba- tion of infant manikins while performing CPR. In the current study, we compared the effectiveness of TruView EVO2 infant optical laryngo- scope (EVAO2; Truphatek Int., Netanya, Israel), TruView infant PCD video laryngoscope (PCD; Truphatek Int.), and MIL during resuscitation with uninterrupted CCs on an infant manikin performed by paramedics.

Methods

Study design and setting

A prospective, Randomized controlled crossover trial design was chosen for this study. This study has been approved by the institutional review board of the International Institute of Rescue Research and Education (Warsaw, Poland; protocol (prot.) no. 12.2014.52.11 on September 14, 2014). After written informed consent was obtained, 78 paramedics volunteered to participate in this trial. All participants were routinely in- volved in management and initial treatment of cardiac arrest in patients at the emergency departments or emergency medical services. None of them had previously used the EVO2 or PCD laryngoscopes. The study

was conducted in the simulation center of the institute.

Study subjects and methods

Before beginning, all participants were given a standard training ses- sion consisting of 2 45-minute lectures on airway anatomy and tracheal intubation with MIL, EVO2, and PCD. The equipment was demonstrated in detail by experienced anesthesiologist. Each participant was allowed to perform practice attempts until all had performed 1 successful tra- cheal intubation with all examined laryngoscopes.

We used the ALS Baby Trainer manikin (Laerdal, Stavanger, Norway), which was designed to be an accurate representation of a 3-month-old infant (11 lb), for performing intubations and CCs. Evalua- tion of the effectiveness of intubation was performed using the software included with manikin. The intubations were performed using EVO2, PCD, and a MIL with a size-1 blade (Fig. 1). A size-3.0 noncuffed tracheal tube (Portex, St. Paul, MN) lubricated with silicon aerosol (Silik’on 4; Novatech SA, Cedex, France) was used for intubation.

During intubation, the manikin was placed on a hard and flat table for an “on the bed” simulation. Chest compressions with the 2-thumb-encircling hands technique were performed by the same basic life support instructor at a rate of 100 compressions per minute and at a depth of about 1.5 in according to the 2010 ERC guidelines [2]. The study was designed as a randomized crossover trial to minimize learning effects. Research Randomizer program was used

[www.randomizer.com] to divide the volunteers into 6 groups and to determine the order in which to apply the different ETI devices within each group. The first group attempted ETI using the EVO2 without CCs, the second using the PCD without CC, the third using the MIL with- out CC, the fourth using the EVO2 with CC, the fifth using PCD with CC, and the sixth using MIL with CC. After completing the ETI procedure, participants had a 15-minute break before performing intubation using another method. Participants were not allowed to watch each other during any of the intubation attempts to avoid any learning effects throughout the procedure.

Data collection

The participants were reminded that the “infant” needs emergency ETI as fast as possible before each attempt to give them a certain feeling of time pressure that would have been present in real emergency pa- tients. The primary outcome of the study was the success rate of intuba- tion. The secondary end point was defined as the time from insertion of the Laryngoscope blade between the teeth to the first manual ventila- tion of the manikin’s lungs were recorded using the stopwatch of a mo- bile phone (Sony Ericsson, Munich, Germany). A failed intubation attempt was defined as an attempt in which the trachea was not intubated or an insertion attempt lasting more than 60 seconds. Partici- pant had maximally 3 intubation attempts in each scenario. A single in- vestigator recorded time for all study participants. After each attempt, participants were asked to rate the glottic view they had during the at- tempt using a Cormack-Lehane grade [10]. To access subjective opinion about the difficulty of the procedure, participants were asked to rate it on a visual analog scale with a score from 1 (extremely easy) to 10 (extremely difficult).

Statistical analysis

The R statistical package for Windows (version 3.0.0) was used for statistical analysis. As data were found not to be normally distributed, nonparametric data were applied. Times needed to successful intuba- tion were compared using the Wilcoxon Signed Rank Test. To detect pos- sible differences in success rates for ETI, the McNemar test was used. For comparisons of visual analog scale, 1-way analysis of variance, with post hoc (Scheffe) test, was used. Results are shown as median values with interquartile range (IQR) or absolute numbers and percentages. A P <=

.05 was taken to indicate statistical significance of a comparison.

Results

Seventy-eight paramedics (17 female, 21.8%) participated in this study. No participant had previously performed an intubation with any video laryngoscope. Forty-nine participants (7 female, 14.3%) worked in teams of emergency medical services, and 29 participants (10 female, 20.4%), in hospital emergency units. Mean age was 30.4 +-

6.9 years, and mean work experience was 7.4 +- 3.9 years.

Fig. 1. Laryngoscopes used for this study were standard MIL (A), EVO2 optical laryngoscope (B), PCD video laryngoscope (C).

874 L. Szarpak et al. / American Journal of Emergency Medicine 33 (2015) 872–875

Table 1

Success rates of intubation according to laryngoscopes and intubation attempts Scenario Laryngoscope Efficacy of intubation attempts

		First attempt (%)	Overall efficacy (%)	Failed (%)
Without CC	EVO2	94.9%	100%	0.0%
	PCD	100%	100%	0.0%
	MIL	97.4%	100%	0.0%
With CC	EVO2	65.4%	94.9%	5.1%
	PCD	100%	100%	0.0%
	MIL	62.8%	92.1%	7.9%

Intubation success

During intubation without CC, the success rate after the first attempt using the distinct EVO2, PCD, and MIL varied and amounted to 94.9% vs 100% vs 97.4% (EVO2, PCD, and MIL, respectively). The overall effective- ness of intubation during resuscitation without CC is presented in Table 1. During intubation with uninterrupted CC, the success rate after the first attempt using the EVO2 was 65.4%, using PCD was 100%, and using MIL was 62.8%. Overall effectiveness in scenario with uninter- rupted CC was highest for the PCD devices (100%) and was lowest for MIL (92.1%, P = .041) and EVO2 (94.9%, P = .047).

We found a statistically significant impact of “work experience” on the effectiveness of intubation with MAC (P = .016) and EVO2 (P =

.042); participants with more experience displayed greater effective- ness during intubation with MAC and EVO2. Work place significantly in- fluenced the successful use of MAC (P = .027) and PCD (P = .034). People working in the emergency medical service performed effective intubation using either MAC or EVO2 significantly more often than peo- ple working in the emergency department. Those dependences did not exist in the case of intubation with PCD.

Time to intubation

The median time to successful intubation using EVO2, PCD, and MIL in scenario with and without CC are presented in Fig. 2. In scenario with uninterrupted CC, time to intubation was achieved fastest when using the PCD (20.2 seconds; IQR, 18-23 seconds) and was significantly slower with all other devices (MIL: 24.4 seconds [IQR, 21-28 seconds], P b .001; EVO2: 25.3 seconds [IQR, 23.1-30.5 seconds], P b .001). Analysis showed that the shortest median time of infant intubation during

scenario without CC was achieved when using PCD (18.3 seconds; IQR, 16-21.3 seconds) and the longest when using EVO2 (24.9 seconds; IQR, 21-29.6 seconds). A statistically significant difference was noticed between PCD and EVO2 (P b .001).

Participants with more experience displayed greater effectiveness during intubation with MAC (P = .09), EVO2 (P = .015), and PCD (P = .045). Work place significantly influenced the time to intubation of MAC (P = .032), EVO2 (P = .024), and PCD (P = .048). People working in the emergency medical service performed effective intubation using MAC, EVO2, and PCD significantly more often than people working in the emergency department.

Quality of glottic view

The quality of glottic view in scenario with and without CC was also best with PCD, where 100% reported a quality of glottic view corre- sponding to a reported Cormack-Lehane classification of I (Table 2).

Ease of use

After intubation attempt, participants were asked to evaluate the ease of implementation of the devices during ETI using a variety of methods. The success rate after using the distinct laryngoscopes in sce- nario with and without CCs varied and amounted to 4.9 vs 3.9 points, re- spectively, for EVO2, 3.6 vs 3.3 points, respectively, for PCD, and 4.2 vs

3.8 points, respectively, for MIL. There is a statistically significant diffe- rence for both the scenarios with and without CCs in the assessment of PCD and MIL (P b .001) and EVO2 (P b .001). There was also a statistically significant difference between MIL and EVO2 in CC scenario (P = .034).

Discussion

For a long period, direct laryngoscopy was the main method of intu- bation algorithms recommended for both adults and children. Both di- rect and video laryngoscopy required appropriate skills from the intubator [1,4,5]. Endotracheal intubation has many benefits. With its use, it is possible to perform asynchronous resuscitation – to conduct rescue breaths without interruptions in CCs. By using endotracheal tube, it is possible to use the positive end-expiratory pressure and to monitor of end-tidal carbon dioxide concentration. Unfortunately, ETI may also entail complications: ETI insertion into the esophagus or inserting it into the right bronchus. In addition, the 2010 ERC guidelines

Fig. 2. Time to intubation.

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Table 2

Grade of glottic view according to the Cormack-Lehane classification that was achieved with the different devices

Scenario Laryngoscope Cormack-Lehane grade

C/L I C/L II C/L III C/L IV Without CC EVO2 78 (100%) 0 (0.0%) 0 (0.0%) 0 (0.0%)

PCD 78 (100%) 0 (0.0%) 0 (0.0%) 0 (0.0%)

MIL 76 (97.4%) 2 (2.6%) 0 (0.0%) 0 (0.0%)

With CC EVO2 77 (98.7%) 1 (1.3%) 0 (0.0%) 0 (0.0%)

PCD	78 (100%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
MIL	69 (88.5%)	9 (11.5%)	0 (0.0%)	0 (0.0%)

Cormack-Lehane (C/L) classification describes the best view possible at laryngoscopy. Data are given in absolute numbers and percentage.

Abbreviations: C/L I, complete glottis visible; C/L II, anterior glottis not seen; C/L III, epiglot- tis seen but not glottis; C/L IV, epiglottis not seen.

recommend that intubation should be performed as soon as possible (b 30 seconds) [2]. Our research indicated that leading continuous CCs significantly reduces the effectiveness of intubation using a standard MIL, but it does not affect the effectiveness of intubation using PCD.

This is the first trial comparing the first-attempt success in ETI during simulated infant CPR with and without CCs using EVO2, PCD, and MIL.

The effectiveness of intubation using a standard MIL during pediatric out-of-hospital intubation performed by paramedics occurred from 45% to 82% [4-7,9]. Komasawa et al [11], in their study, showed that ETI ef- fectiveness during resuscitation performed by 22 staff physicians who work routinely in pediatric intensive care and emergency medicine depended on the factor CCs were performed. Endotracheal intubation effectiveness during uninterrupted CCs was 70% and, in scenario with- out CC, was 100% [11]. In another study by Komasawa et al [12], concerning the intubation by novice physicians during infant CPR sim- ulation, overall effectiveness of intubation using MIL during CPR with and without CCs was 60.9% vs 95.6%, respectively. In prospective studies examining prehospital intubation of children by physicians with a spe- cialization in emergency medicine, first intubation attempt effective- ness through the mouth was varied and was 53.9% for infants, 68.2% for children younger than 5 years, and 95.7 for children aged 6 to 14 years [13]. In our study, success of intubation during uninterrupted CCs was 92.1% and, in scenario without CC, was 100%. Higher efficiency of intubation in our trial may be caused by the fact that paramedics in Poland are taught intubation, which is a key skill in the practice of emer- gency medical service.

Singh et al [14], in their trial, found that, in neonates and infants, the tracheal intubation using EVO2 blade took almost as much time as Mill- er blade and provided improved laryngoscopy view as compared with the Miller blade. In our study, the quality of glottic view in scenarios with and without CCs according to the Cormack-Lehane classification was better with the EVO2 than MIL; however, the best glottic view was reported when PCD was used. Because this is the first study com- paring the effectiveness of infant intubation using EVO2 and PCD, it is impossible to refer our own results to other authors.

This study has limitation. It was carried out on a manikin and not on humans; therefore, it is difficult to predict the actual performance of the devices in the clinical setting. However, according to the International Liaison Committee on Resuscitation, randomized clinical trials for cases of cardiac arrest are unethical and cannot determine the expected benefits of CPR [15]. The strength of this study includes the use of a

highly advanced patient simulator for performing pediatric advanced life support and the randomized crossover procedure.

Conclusions

For infant tracheal intubation with PCD, when used by paramedics, the malleable PCD showed shorter intubation time and higher overall success rate in a simulated CC scenario than EVO2 or MIL. Further clini- cal studies are necessary to confirm these initial positive findings.

Acknowledgments

There are no sources of financial and material support to be declared. The authors want to thank all nurses for their participation in this study.

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