Comparison of intubation through the mcgrath mac, glidescope, airtraq and miller laryngoscope by paramedics during child cpr a randomized crossover manikin trial

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Original Contribution

Comparison of intubation through the McGrath MAC, GlideScope, AirTraq,

and Miller Laryngoscope by paramedics during child CPR: a randomized

crossover manikin trial

☆

,

☆☆

,

★

Lukasz Szarpak, PhD, MPH, EMT-P

a,

⁎

, Katarzyna Karczewska, MD

b

, Togay Evrin, MD

c

,

Andrzej Kurowski, PhD, MD

d

_{, Lukasz Czyzewski, PhD, RN}

d,e

a

Department of Emergency Medicine, Medical University of Warsaw, Warsaw, Poland

b

Anesthesiology and Intensive Care Unit, Mazovian Regional Hospital, Radom, Poland

c_{Department of Emergency Medicine, UFuK University Medical faculty Dr. Ridvan Ege Education and Research Hospital, Ankara, Turkey} d

Department of Anesthesiology, Cardinal Wyszynski National Institute of Cardiology, Warsaw, Poland

e

Department of Nephrologic Nursing, Medical University of Warsaw, Warsaw, Poland

a b s t r a c t

a r t i c l e i n f o

Article history:

Received 28 February 2015

Received in revised form 26 March 2015 Accepted 8 April 2015

Backgroud: Advanced airway management and endotracheal intubation (ETI) during cardiopulmonary resuscitation (CPR) is more difﬁcult than, for example, during anesthesia. However, new devices such as video laryngoscopes should help in such circumstances. The aim of this study was to compare the performance of 4 intubation devices in pediatric manikin-simulated CPR.

Methods: One hundred two paramedics participated in this study. None had prior experience in video laryngoscopy. After a standardized audiovisual lecture lasting 45 minutes, the paramedics participated in a practical demonstration using the advanced pediatric patient simulator PediaSIM CPR (FCAE HealthCare, Sarasota, FL), which was designed to be an accurate representation of a 6-year-old child. Cardiopulmonary resuscitation was performed using LUCAS-2 (Physio-Contro, Redmond, WA). Afterward, paramedics were instructed to perform ETI using 4 intubation devices (MacGrathMAC, GlideScope, AirTraq, and Miller Laryngoscope Blade [Miller]) in a randomized sequence. The primary outcome was the success rate of tracheal intubation. The secondary outcome was the time to intubation. Results: The mean time to intubation was 30.7 ± 15.3, 28.6 ± 15.9, 24.1 ± 5.0, and 39.3 ± 14.7 seconds (McGrath, GlideScope, AirTraq, and Miller, respectively); and the success ratio of intubation for the devices was 100% vs 100% vs 100% vs 77.5%, respectively.

Conclusions: Child ETI performed by paramedics during uninterrupted chest compression often has a low success rate. In contrast, McGrath, GlideScope, and AirTraq intubation devices are fast, safe, and easy to use. Within the limitations of a manikin study, this study suggests that inexperienced medical staff might beneﬁt from using video laryngoscopy devices for child emergency airway management.

1. Introduction

According to the 2010 European Resuscitation Council guidelines on resuscitation, endotracheal intubation (ETI) is still regarded as the crite-rion standard for securing the airway in prehospital emergency medicine

[1]. Consideration should be given to the fact that pediatric intubation is a

difﬁcult skill to learn and requires continual exposure to maintain com-petence[2], as a lack of exposure results in a high failure rate, regardless of the professional background of the intubator[3].

However, a different approach to the standard adult Macintosh

laryngoscopy [4,5] is needed for children because of anatomical

differences in the throats of children. Miller’s laryngoscope blade has been a commonly used laryngoscope blade for pediatric intubation since 1941[6], but this form of direct laryngoscopy requires great skill from the intubator. In many cases, it is impossible to see the glottis using this laryngoscope; therefore video laryngoscopes (ie, McGraph or GlideScope) or optical laryngoscopes (ie, AirTraq) that make it possible for the intubator to observe the glottis might facilitate the process of intubation[7,8].

The aim of the study was to compare time and success rates of different available video laryngoscopes and the Miller laryngoscope for emergency intubation during simulated pediatric cardiopulmonary resuscitation (CPR).

☆ Funding: This study was ﬁnanced by the authors' own resources. There was no ﬁnancial support by any of the companies mentioned in this manuscript.

☆☆ Authors’ contributions: conception and design: KK, TE, LS, AK, LC; analysis and inter-pretation: LS; drafting the manuscript for important intellectual content: KK, TE, LS, AK, LC. ★ Conflict of interest statement: The authors declare that they have no conflicts of interest. There are no sources offinancial and material support to be declared. None of the companies were involved in any way in the study design, planning, execution, or analysis as well as in the writing of this manuscript.

⁎ Corresponding author. Department of Emergency Medicine, Medical University of Warsaw, Lindleya 4 St, 02-005 Warsaw, Poland. Tel.: +48 500186225.

E-mail address:lukasz.szarpak@gmail.com(L. Szarpak).

http://dx.doi.org/10.1016/j.ajem.2015.04.017

Contents lists available atScienceDirect

American Journal of Emergency Medicine

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2. Materials and methods 2.1. Study population

The participants in this trial were recruited from resuscitation trainees at the International Institute of Rescue Research and Education (Warsaw, Poland). A randomized crossover trial design was chosen, and the study was approved by the institutional review board of the Interna-tional Institute of Rescue Research and Education (Warsaw, Poland; Prot. No.: 12.2014.06.24).

After written informed consent was obtained, 102 paramedics participated in the study. All participants had previous experience with the Miller laryngoscope; however, none of them had used video laryngoscopes before. The study was conducted between April and September of 2014.

2.2. Study design

Before the trial, all participants attended a 45-minute training session that included an introduction to the anatomy of the respiratory tract and the techniques of insertion and ventilation using McGrath MAC (Covidien plc, Dublin, Ireland), GlideScope (Verathon Inc, Bothell, WA), AirTraq (Prodol Meditec, Fenton, MO), and Miller Laryngoscope (Mercury Medical, Clearwater, FL) (criterion standard). At the end of the training session, the participants practiced the use of these devices. During the practical exercise, we used a Pediatric McGRAPH MAC Blade, GlideScope 2.0, AirTraq Pediatric, and Miller Blade No. 2 and 4.0-mm I.D. tracheal tubes. All intubation attempts were done with a PediaSIM CPR training mannequin (FCAE HealthCare, Sarasota, FL), which was designed to be an accurate representation of a 6-year-old child. To simulate the difﬁculties associated with intubation during resuscitation, CPR was performed using LUCAS-2 (Physio-Contro, Redmond, WA). Each participant inserted all 4 supraglottic airway devices in a computer-generated randomized sequence (Research Randomizer [www.randomizer.org]). After each device, the participant took a 20-minute rest and then had to perform intubation using the next device. The participants were not allowed to watch each other to avoid any learning effect through observation.

The primary end point of the study was the success rate of blind tracheal intubation, whereas the secondary end point was deﬁned as the time from insertion of an intubation device to theﬁrst manual ven-tilation of the mannequin’s lungs. If the examinee failed at all attempts, the case was excluded from the time calculations.

When the intubation procedure was complete, participantsﬁlled out a questionnaire to rate the ease of the intubation attempt with each device on a 5-point Likert scale (1 = extremely difﬁcult; 5 = extremely easy). Participants were also asked which laryngoscope they would prefer in a real-life intubation.

Apart from these data, sociodemographic data such as sex (male, female), age (in years), level of education (bachelor, master), work experience (in years), and work place (emergency department [ED] or emergency medical services [EMS]) were documented.

2.3. Statistical evaluation

The R statistical package for Windows (version 3.0.0) was used for statistical analysis. Results are shown as means ± standard deviation or absolute numbers and percentages. Times needed to successful intu-bation were compared using the Wilcoxon signed rank test. McNemar test was used to detect possible differences in success rates for ETI. Moreover, multivariate regression analysis models (analysis of variance) were used to assess the impact of sex, age, education level, work expe-rience, profession, place of work, and the efﬁciency of blind intubation. A P value of less than .05 was considered as statistically signiﬁcant.

3. Results

3.1. Demographic data

One hundred two paramedics (43 female, 42.2%) participated in this study. The characteristics of participants are shown inTable 1. No participant had previously performed a video intubation with any video laryngoscopes. Each participant inserted all 4 intubation devices in a computer-generated randomized sequence (Figure). Sixty-nine participants (27 female, 39.1%) worked in teams of EMS, and 33 participants (16 female, 69.6%) worked in hospital EDs. Mean age was 32.7 ± 9.8 years, and mean work experience was 10.5 ± 5.2 years. 3.2. Success of ETI

The success rate after theﬁrst attempt using the distinct intubation methods varied and amounted to 86.3% vs 71.6% vs 87.3% vs 67.4% (McGrath, GlideScope, AirTraq, and Miller). On the second attempt, intubation success rate was 13.7% vs 26.5% vs 12.7 vs 7.8%. The overall effectiveness of intubation during simulated pediatric CPR is presented inTable 2. There was a statistically signiﬁcant difference between Miller Laryngoscope and AirTraq (Pb .001), as well as GlideScope (P b .001)

and McGrath (P b .001). Intubation using video laryngoscopes

(McGrath, GlideScope, and AirTraq) was more effective than direct laryngoscopy using the Miller Laryngoscope.

3.3. Intubation time

The average time to successful intubation using McGrath, GlideScope, AirTraq, and Miller Laryngoscope is presented inTable 1. The analysis shows that the shortest average time of intubation during pediatric CPR was achieved when using AirTraq (24.1 ± 5.0 seconds) and was lon-gest when using Miller Laryngoscope (39.3 ± 14.7 seconds). A statistical-ly signiﬁcant difference was noticed between AirTraq and McGrath (P = .032) and Miller (Pb .001). There was also a statistically signiﬁcant differ-ence between time to successful intubation between GlideScope and Miller (Pb .001) and also between McGrath and Miller (P = .016). 3.4. Multivariate regression analysis

Using multivariate regression analysis, the impact of sociodemographic data (age, sex, level of education, work experience, and work place) on the effectiveness of blind intubation with regards to the various intuba-tion devices was analyzed (Table 3). We found“level of education” to have a statistically significant effect on the effectiveness of intubation with the Miller Laryngoscope (P = .043) in that participants with a master degree displayed greater effectiveness during intubation with this device.“Work place” and “work experience” also significantly influenced the successful use of the Miller Laryngoscope (P = .019 and P = .007, respectively). People with more experience as well as people working in EMS teams performed effective intubation using the Miller Laryngoscope significantly more often than people with less work experience and people working in emergency hospital units.

Table 1

Characteristics of paramedics entered into the study

Parameter Female (n = 43) Male (n = 59) Total (N = 102) Age (y) 31.5 ± 16.5 34.2 ± 12.5 32.7 ± 9.8 Work experience (y) 10.5 ± 7.5 12.4 ± 7.4 10.5 ± 5.2 Level of education Master 20 (46.5%) 26 (61.1%) 46 (45.1%) Bachelor 23 (53.5%) 23 (38.9%) 56 (54.9%) Work place EMS 27 (62.8%) 42 (71.2%) 69 (67.6%) ED 16 (37.2%) 17 (28.8%) 33 (32.4%)

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3.5. Subjective assessment

Participants' subjective assessment of intubation with the McGrath, GlideScope, AirTraq, or standard Miller Laryngoscope showed no signi ﬁ-cant differences between the intubation methods. Participants' subjec-tive assessment of intubation with McGrath, GlideScope, AirTraq, and Miller varied and amounted to 3.6 ± 1.5 points vs 3.4 ± 1.7 points vs 3.4 ± 1.5 points vs 3.2 ± 0.6 points. Concerning preferences on hypo-thetical real-life intubation during pediatric CPR, 86.3% voted for intuba-tion with video laryngoscopes and 13.6% for intubaintuba-tion with direct laryngoscopy using the Miller Laryngoscope.

4. Discussion

Current European Resuscitation Council 2010 guidelines emphasize the delivery of continuous chest compression with as few interruptions as possible, including pauses for airway management efforts[1]. Airway management is considered to be an essential element of both in-hospital and prehospital CPR for pediatric intubation. Intubation is a technically

challenging skill to learn and requires continued exposure to prevent skill deterioration[9–11]. Hubble et al[9]identiﬁed that 1 in 6 pediatric intubation attempts by paramedics resulted in failure. Simulation technology used in this study offers a unique opportunity for continued learning and assessment. Although ETI can be performed asynchronous-ly resuscitation, thus shorten the out-of chest compression time[10].

In this study, we compared 4 intubation devices (McGrath, GlideScope, AirTraq, and Miller) in a simulated scenario of pediatric re-suscitation in a group of 102 paramedics with regard to success rate, time tofinal placement, and rating of the respective intubation device. No study has previously compared the McGrath, GlideScope, AirTraq, and Miller in use by paramedics in a pediatric CPR scenario. The mainfindings of the study are that video and optical laryngoscopes may provide benefits regarding success rate, time to final placement, and ease of use (represented by subjective ratings) and that the

Figure. Flowchart of design and recruitment of participants according to CONSORT statement.

Table 2

Time to and success of intubation

Device Time to intubation (s) Tracheal intubation attempts

First (%) Second (%) Third (%) Failed (%) McGrath 30.7 ± 15.3 86.3% 13.7% 0.0% 0.0% GlideScope 28.6 ± 15.9 71.6% 26.5% 1.9% 0.0% AirTraq 24.1 ± 5.0 87.3% 12.7% 0.0% 0.0% Miller 39.3 ± 14.7 67.4% 7.8% 2.3% 22.5%

Table 3

Multivariate regression analysis—the impact on the results Device Statistical

parameter

Sociodemographic data Age Sex Level of

education Work experience Work place McGrath β 0.038587 0.048382 0.048395 0.047385 0.048563 P value .694 .128 .078 .068 .076 GlideScope β 0.048298 0.038583 0.034735 0.034755 0.047398 P value .529 .339 .285 .059 .063 AirTraq β 0.037295 0.0482373 0.03854 0.037586 0.038589 P value .392 .943 .386 .084 .055 Miller β 0.047293 0.044723 0.038532 0.037285 0.038539 P value .745 .184 .043 .007 .019

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effectiveness of pediatric intubation depends largely on the work expe-rience of paramedics. Profession, whether EMS or ED, age, sex, or level of education had no effect on the success rate of the intubation.

The most importantfinding of our study was that intubation using AirTraq was significantly quicker than that with the Miller or McGrath MAC devices. The McGrath, GlideScope, and AirTraq devices performed significantly better in terms of overall intubation effectiveness than Mill-er. Orliaguet et al[12]and Savoldelli et al[13]also indicate that, for those with no previous experience with video laryngoscopy intubation, using AirTraq is the most effective. As several authors have shown, the McGrath MAC video laryngoscope provides a better view of the glottis than a Macintosh laryngoscope[7,8,14,15]; but it is not as easy to insert an endotracheal tube through the vocal cords because a video laryngoscope has a much greater curvature than that of a conventional direct laryngoscope, whereas an endotracheal tube has a different curvature altogether[7,16]. Our study is thefirst study showing intuba-tion effectiveness of McGrath MAC during simulated resuscitaintuba-tion of a pediatric patient. Analysis of our study showed an overall success rate of 100% during intubation using McGrath MAC. The effectiveness of the first attempts of intubation using McGrath MAC was 86.3%, with an aver-age time of 30.7 seconds. Ng et al[16], using McGrath MAC in intubating adult patients with potentially difficult airways, showed the effective-ness offirst intubation attempt to be 69.2% and overall effectiveness to be 100%. A 100% intubation ef_{ficiency using McGrath MAC was also} re-ported in studies by Shippey et al[17]and Negishi et al[14].

The overall success rate of intubation using GlideScope in our study was also 100%, with effectiveness of_{ﬁrst intubation attempt being} 71.6%. Average time toﬁnal placement was 28.6 seconds. Iwai et al

[18]and Griesdale et al[19]also reported high success rates using GlideScope in patients with restricted airway access. Kim et al[20] re-ported that the intubation performance of novices using the McGrath MAC was equal to their performance using the GlideScope Ranger in regular simulated airways.

During pediatric intubation without chest compression interruption with AirTraq, the average intubation time was 24.1 seconds. The effec-tiveness of theﬁrst intubation attempts was 87.3%, and the overall effec-tiveness was 100%; as it was with McGrath and GlideScope. Komasawa et al[21]reported time to intubation to be 17.1 ± 5.0 seconds. Castle

et al[22]recommended the use of AirTraq for airway management

by paramedics in out-of-hospital CPR. Komasawa et al [21] and

Gómez-Ríos et al[23]also reported high success rates and fast insertion times for the AirTraq.

Intubation time in the study of Castle et al[22]was longer at 31.8 seconds, possibly because of the fact that paramedic students par-ticipated in their study, whereas our study used professionally active paramedics with a minimum of 1 year of work experience, which also translates into greater intubation experience. Data from our study also show good performance and high success rates, and skill retention was promising.

The Miller laryngoscopy blade is a_{“criterion standard” in pediatric} intubation both in hospital and in prehospital care. In this study, average time of intubation using Miller was 39.3 ± 14.7 seconds. The overall ef-fectiveness of intubation using Miller was 77.5%. These results con_ﬁrm studies from Komasawa et al[21], in which the average intubation time was 39.5 ± 16.4 seconds and overall effectiveness of intubation was 70%[21]. A similar intubation efﬁcacy of 74% has also been demon-strated by Castle et al[22]for the Miller blade.

Multivariate regression analysis showed that only in the case of intu-bation with the Miller was there a statistically signiﬁcant effect of work experience, work place, and education level on the effectiveness of CPR. This conﬁrms the thesis that direct laryngoscopy requires great skill and experience from the intubator[11,12,21,24–28]. In the case of McGrath, Glidescope, and AirTraq, there was no effect of sociodemographic parameters on the effectiveness of intubation.

Moreover, all participants in the study only had intubation experience with the Miller blade. One can conclude that paramedics very quickly

learn to operate and effectively perform intubation using the McGrath, Glidescope, and AirTraq. These devices can be an alternative to direct intubation, especially for persons without the necessary skills or in the event of difﬁculties in seeing the glottis[1,29,30].

There are some limitations in our study. This study was conducted on a standardized airway model. Manikin studies can never fully replace studies in humans; however, the decision to use a standardized airway model was made intentionally, as intubation conditions would never have been comparable due to interindividually differing anatomical sit-uations. Besides, these intubation devices have not been compared in this situation in a randomized, crossover, controlled trial. Thus, the pos-sibility of a disadvantage resulting from the use a possibly inferior de-vice could not be ruled out in advance.

5. Conclusions

Within the limitations of this manikin setting, it might be suggested that, in emergency situations, safe and effective alternatives to ETI are available. Endotracheal intubation should preferably only be performed by trained and experienced physicians or paramedics. The data obtained in our manikin study show that McGrath, GlideScope, and AirTraq are alternatives to Miller that are equally as easy to use and effective during ongoing child chest compressions. Clinical accumulation and randomized trials of the use of McGrath vs GlideScope vs AirTraq vs Miller in patients receiving pediatric CPR in clinical situations are needed in the future. Acknowledgements

The authors would like to thank the participants. References

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