American Journal of Emergency Medicine 33 (2015) 1084–1088

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Brief Report

Comparison of 4 Supraglotttic Devices Used by Paramedics During Simulated CPR : A Randomized Controlled Crossover Trial☆,☆☆,★,★★ Łukasz Szarpak, PhD, MPH, EMT-P a,⁎, Andrzej Kurowski, MD, PhD b, Zenon Truszewski, PhD, MD a, Oliver Robak, MD, PhD c, Michael Frass c a b c

Department of Emergency Medicine, Medical University of Warsaw, Warsaw, Poland Department of Anesthesiology, Institute of Cardiology, Warsaw, Poland Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria

a r t i c l e

i n f o

Article history: Received 25 March 2015 Received in revised form 23 April 2015 Accepted 24 April 2015

a b s t r a c t Background: Ensuring an open airway during cardiopulmonary resuscitation is fundamental. The aim of this study was to determine the success rate of blind intubation during simulated cardiopulmonary resuscitation by untrained personnel. Methods: Four devices were compared in a simulated resuscitation scenario: ILMA (Intavent Direct Ltd, Buckinghamshire, United Kingdom), Cobra PLA (Engineered Medical Systems Inc, Indianapolis, IN), Supraglottic Airway Laryngopharyngeal Tube (SALT) (ECOLAB, St. Paul, MN), and Air-Q (Mercury Medical, Clearwater, FL). A group of 210 paramedics intubated a manikin with continuous chest compressions. Results: The mean times to intubation were 40.46 ± 4.64, 33.96 ± 6.23, 17.2 ± 4.63, and 49.23 ± 13.19 seconds (SALT vs ILMA, Cobra PLA, and Air-Q; P b .05). The success ratios of blind intubation for the devices were 86.7%, 85.7%, 100%, and 71.4% (SALT vs ILMA, Cobra PLA, and Air-Q; P b .05). Conclusion: The study showed that the most efficient device with the shortest blind intubation time was the SALT device. © 2015 Elsevier Inc. All rights reserved.

1. Introduction Securing an airway in a medical emergency is crucial for medical professionals. During cardiac arrest, the body's oxygen reserves are sufficient for 3 to 5 minutes only [1]. Soon after, vital organs are irreversibly damaged, starting with the central nervous system and cardiac muscle [2]. Rapid implementation of chest compressions and sufficient ventilation are the key elements of emergency measures [3]. Apart from restoring circulation, a secure airway is essential to ensure ventilation [4] during cardiac arrest. The European Resuscitation Council guidelines recommend endotracheal intubation (ETI) as the criterion standard for securing airways [1]. In addition to oxygenation, ETI also provides protection against regurgitation and aspiration of gastric contents into

☆ Author's contributions: Conception and design: LS, ZT, and AK; analysis and interpretation: AK, ZT, and LS; and drafting the manuscript for important intellectual content: LS, AK, ZT, OR, and FM. ☆☆ Source of support: No sources of financial and material support to be declared. ★ Conflict of interest statement: No conflict of interest to declare. ★★ Funding: Institutional funding only. ⁎ Corresponding author at: Department of Emergency Medicine, Medical University of Warsaw, Lindleya 4 St, 02-005 Warsaw, Poland. Tel.: +48 500186225 (mobile). E-mail address: [email protected] (Ł Szarpak). http://dx.doi.org/10.1016/j.ajem.2015.04.050 0735-6757/© 2015 Elsevier Inc. All rights reserved.

the lungs. Paramedics are therefore trained in ETI, usually with the Macintosh laryngoscope. However, ETI is fraught with many complications, including broken teeth, damage to the internal structures of the nasopharynx, and bleeding. In addition to complications during standard ETI, paramedics must also contend with movement of the patient during cardiopulmonary resuscitation (CPR), difficult airway access, or limited access to the patient's head. Furthermore, even in the hands of experienced anesthesiologists, right main stem bronchus or esophageal intubation occurs frequently [5]. For such situations, supraglottic airway devices (SADs) were developed in the 1980s that allowed insertion without a laryngoscope, a technique often referred to as “blind intubation [1,6,7].” These devices are nowadays widespread and in use all over the world, both in hospitals and in preclinical settings. The main advantages of SADs are that almost no training is required [8], use in emergency situations is feasible and safe [9], and success rates are comparable with ETI [10]. Because paramedics are often the first medical professionals on site in an emergency, it is important that they are able to secure an airway quickly and safely even under adverse conditions and with limited training only. A few studies have evaluated the use of SADs during ongoing CPR [11-13], with chest compression being the most difficult obstacle to overcome when attempting intubation [13]. Because of the lack of evidence, it still remains a matter of discussion whether specific SADs provide benefits in such settings [11].

Ł. Szarpak et al. / American Journal of Emergency Medicine 33 (2015) 1084–1088

The aim of the study was therefore to evaluate 4 different SADs during CPR practiced by paramedics to provide evidence for choosing a rescue airway device for resuscitation.

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(ANOVA) test was used to assess the impact of sex, age, education level, work experience, place of work, and the efficiency of blind intubation. Results were considered statistically significant at a 2-sided P value of b .05.

2. Methods 3. Results 2.1. Study design 3.1. Demographic testing The study was conducted between January and July of 2014. Two hundred ten paramedics received training in blind intubation with the 4 SADs, organized by the International Institute of Rescue Research and Education (Warsaw, Poland). All participants had previous experience with the Macintosh laryngoscope; however, none of them had used SADs before. The study was approved by the Executive Scientific Committee of the International Institute of Rescue Research and Education (protocol no.: 4.2014.11.16). We first conducted a 45-minute training for all participants, including an introduction to the anatomy of the respiratory tract and the techniques of insertion and ventilation using ILMA (Intavent Direct Ltd, Buckinghamshire, United Kingdom), Cobra PLA (Engineered Medical Systems Inc, Indianapolis, IN), Supraglottic Airway Laryngopharyngeal Tube (SALT) (ECOLAB, St. Paul, MN), and Air-Q (Mercury Medical, Clearwater, FL) (Fig. 1). At the end of the training session, the participants practiced the use of these devices. During the practical exercise, we set the 4 devices with 7.0-mm internal diameter. All intubation attempts were done with a METIman Prehospital CPR training manikin (CAE HealthCare, Saint-Laurent, Quebec, Canada). To simulate the difficulties associated with intubation during resuscitation, CPR was performed with LUCAS-2 (Physio-Control, Redmond, WA). Each participant inserted all 4 SADs in a computer-generated randomized sequence (Research Randomizer [14]) (Fig. 2) during ongoing chest compressions. After each device, the participant took a 10-minute rest and then had to perform intubation using the next device. The participants were not allowed to watch each other to avoid learning through observation. The success of intubation was verified by successful ventilation and the rising of the manikin's chest. Time to intubation was measured with a stopwatch from the picking up of a SAD to the first visible ventilation of the lungs in absence of gastric inflation. Apart from these data, sociodemographic data such as sex (male and female), age (in years), level of education (bachelor and master), work experience (in years), and work place (emergency department [ED] or emergency medical service [EMS]) were documented. 2.2. Statistical analysis The results were analyzed using the R statistical package for Windows (version 3.0.0). Results are reported as mean and ±SD. The differences in the effectiveness of individual CPR parameters were analyzed using the χ 2 independence test. Moreover, an analysis of variance

Two hundred ten paramedics (92 female, 43.8%) participated in this study. No participant had previously performed blind intubation with any SAD. One hundred twenty-nine participants (53 female, 41.1%) worked in teams of EMS and 81 participants (39 female, 48.1%) in hospital emergency units. Mean age was 31.03 ± 8.55 years, and mean work experience was 8.94 ± 7.22 years. 3.2. Success rate The success rate after the first attempt using the distinct SADs varied and amounted to 76.7% vs 58.1% vs 90.5% vs 54.7% (ILMA, Cobra PLA, SALT, and Air-Q). For the second attempt, the intubation success rate was 7.6% vs 18.1% vs 8.1% vs 8.1%, respectively and on the third intubation attempt was 2.4% vs 9.5% vs 1.4% vs 8.6%. The overall effectiveness of blind intubation is presented in Table 1. There was a statistically significant difference in the success rate of the intubation between SALT and ILMA (P = .028) as well as Cobra PLA (P = .042) and Air-Q (P = .017). Intubation using SALT was the most effective method of the 4 SADs. 3.3. Time to successful intubation The average successful intubation times using ILMA, Cobra PLA, SALT, and Air-Q are presented in Fig. 3. The analysis showed that the shortest average intubation time during CPR was achieved with SALT (17.2 ± 4.6 seconds) and the longest when using Air-Q (49.2 ± 19.6 seconds). A statistically significant difference was noticed between SALT and ILMA (P = .013), Cobra PLA (P = .022), and Air-Q (P = .004). There was also a statistically significant difference between the time to successful intubation between ILMA and Air-Q (P = .033) and between Cobra PLA and Air-Q (P = .031). 3.4. Multivariate regression analysis An ANOVA test was used for multivariate ANOVA. Sociodemographic variables were selected as independent variables: age (in age groups), sex (male and female), education (higher secondary), work experience (at intervals), and place of work (ED and emergency medical mobile team). The dependent variable is shown as the efficiency of intubation according to the SAD (Table 2). We found a statistically

Fig. 1. Supraglottic airway devices used in this trial: ILMA (A), Cobra PLA (B), Air-Q (C), SALT (D).

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Fig. 2. Manikin with mechanical chest compression system Lucas-2.

significant impact of “work experience” on the effectiveness of intubation with ILMA (P = .004), Cobra PLA (P = .003), and Air-Q (P = .008): participants with more experience displayed greater effectiveness during intubation with ILMA, Cobra PLA, and Air-Q. Work place significantly influenced the successful use of the ILMA (P = .021), Cobra PLA (P = .041), and Air-Q (P = .027). People working in EMS performed effective intubation using ILMA, Cobra PLA, or Air-Q significantly more often than people working in EDs.

3.5. Rating of the distinct SADs Participants evaluated each device during blind intubation based on the subjective ease with which they performed the procedures. The

Table 1 Percentage of participants with successful blind tracheal intubation after first, second, and third attempt at ILMA, Cobra PLA, SALT, and Air-Q Tracheal intubation attempts

ILMA

Cobra PLA

SALT

Air-Q

First (%) Second (%) Third (%) Failed (%)

76.7% 7.6% 2.4% 13.3%

58.1% 18.1% 9.5% 14.3%

90.5% 8.1% 1.4% 0.0%

54.7% 8.1% 8.6% 28.6%

SAD, which proved easiest to use was SALT, which in the case of CPR received an average rating of 1.66 points (Table 3). 4. Discussion In this study, we compared 4 distinct SADs (ILMA, Cobra PLA, SALT, and Air-Q) in a simulated resuscitation scenario with a group of 143 paramedics with regards to success rate, time to final placement, and rating of the respective SADs. The main findings of the study are that the SALT may provide benefits regarding success rate, time to final placement, and ease of use (represented by subjective ratings) and that the effectiveness of blind intubation depends largely on the work experience of paramedics. Profession, whether EMS or ED, age, sex, or level of education, had no effect on intubation success rates. Our study showed an overall success rate of 100% during blind tracheal intubation using SALT. This result was higher than in trials performed by Bledsoe et al [15] with 91%, Uribe-Valencia et al [16] with 90%, and Anand et al with 40% [17]. The effectiveness of the first attempts of intubation using SALT was 91.6%, with an average time of 16.94 seconds. The result was 16 seconds less than that of UribeValencia et al [16] in their tests. The effectiveness of intubation using SALT and the fact that age, sex, education as well as experience and employment do not affect

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Fig. 3. Comparison of time with intubation of the 4 study devices in seconds.

intubation efficiency while practicing this method suggest that SALT can be used by people both with and without experience. However, work experience affected intubation success rates with ILMA, Cobra PLA, and Air-Q. This may be associated with the skills acquired when using a standard intubation device such as the Macintosh laryngoscope. The overall effectiveness of intubation using the ILMA in our study was 88.97%, in which the effectiveness of the first trial was 76.29%. Average time until final placement was 39.9 seconds. This is comparable with other studies in the literature: Khan [18] used the LMA Fastrach with a score of 88.4% and an average intubation time of 46.7 seconds during the first intubation attempt. Gaszynska et al [19] obtained 97% within an average time of 28.2 seconds. A shorter intubation time was obtained using the ILMA by Sherren et al [20] (22.8 seconds), Darlong et al [21] achieved an effectiveness of 90% during intubation using ILMA, and, in the tests performed by Garzón Sánchez et al [22], the effectiveness was 90%. However, Sastre et al [23] showed an effectiveness of 70%. Participants with more work experience as well as those employed in EMS have used the ILMA significantly more often compared with less experienced employees and those working in EDs so were therefore more successful in performing blind intubation with this SAD. The reason behind this may be that EMS paramedics more frequently perform tracheal intubation using Macintosh or Miller laryngoscopes, whereas in EDs, there is always an anesthesiologist present who is responsible for intubation.

Table 2 Multivariate regression analysis—the impact on the results Efficacy of intubation

Statistical parameter

Sociodemographic parameter Age

Sex

Level of education

Work experience

Work place

ILMA Cobra PLA SALT Air-Q

P value P value P value P value

0.083 0.075 0.253 0.068

0.753 0.674 0.829 0.826

0.058 0.063 0.175 0.081

0.004 0.003 0.075 0.008

0.021 0.041 0.842 0.027

During blind intubation with Cobra PLA, the average intubation time was 32.5 seconds. The effectiveness of the first attempts of intubation was 60.13%, and the overall effectiveness was 86%. The highest intubation effectiveness was obtained by Mathew et al [24] with 98%, whereas Darlong et al [21] achieved 87%. The Air-Q airway device is also a device used for blind intubation, although, in this case, it is recommended to use a fiber-optic guide. In this study, the participants performed intubation using Air-Q without a guide. Average time of intubation using Air-Q in this study was 51.6 seconds. The effectiveness of intubation using the Air-Q was 69.22%. In the scientific literature, the effectiveness of intubation using an Air-Q is comparable: Sohn et al [25] with 60.3%, Garzón Sánchez et al [22] with 60%, and Karim and Swanson [26] with 77%. A major limitation of our study and of most of studies in this field is the use of manikins, so therefore it is difficult to predict the performance of the devices during actual CPR. Another limitation might be that the devices were evaluated in a simulated physiologic airway because the scope of our study was to assess their performance during chest compression and not to investigate their role in difficult airway management. Conclusions can therefore not be generalized to pathologic airway situation like clenched jaw or swollen tongue due to anaphylaxis. The main question, which always arises while conducting research on manikins, is what impact the obtained results have on clinical research. Results from a manikin study can usually not be applied to a similar situation in humans without significant limitations. We are very well aware of the ethical and moral dilemma that comes with conducting research in critical care situations, but from a scientific point of view, future research should be carried out within a clinical setting on real patients during CPR to confirm the effectiveness of blind intubation with distinct SADs. This would eliminate the biggest limitation of all manikin studies. Furthermore, tests should additionally be conducted among doctors and nurses, as these are staff who may encounter the need for patient intubation. Supraglottic airway devices were designed for difficult airway situations or situations in which only limited training is possible. As demonstrated in our study, the effectiveness of blind intubation while using the SALT device was 100%. This was the most effective device for blind

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Table 3 Difficulty to intubate with ILMA, Cobra PLA, SALT, and Air-Q as perceived by the participants Device

ILMA Cobra PLA SALT Air-Q

Ease of use rated by the participants 1 (Very easy)

2

3

4

5 (Very hard)

Total

Mean

57 (27.1%) 48 (22.9%) 98 (46.7%) 15 (7.1%)

85 (40.5%) 75 (35.7%) 103 (49.0%) 31 (14.8%)

44 (21.0%) 61 (29.0%) 8 (3.8%) 67 (31.9%)

21 (10.0%) 14 (6.7%) 1 (0.5%) 65 (31.0%)

3 (1.4%) 12 (5.7%) 0 (0.0%) 32 (15.2%)

210 (100%) 210 (100%) 210 (100%) 210 (100%)

2.2 2.4 1.6 3.3

intubation out of all the tested devices. The ratings showed that according to our group of paramedics, the SALT device was also easiest to use. We therefore propose that the investigated SADs may be used for blind intubation during CPR. However, it should be kept in mind that SALT does not provide an effective seal against aspiration. 5. Conclusion In summary, our study provides evidence that the SALT might provide benefits during blind intubation during continuous CPR in manikins, with paramedics having the highest success rate, the shortest time to final placement, and the best subjective assessment with this SAD. Nevertheless, the performance of all tested devices (SALT, ILMA, Cobra PLA, and Air-Q) during CPR proved satisfactory and should be used for further clinical evaluations. Acknowledgments Nothing to acknowledge. References [1] Deakin CD, Nolan JP, Soar J, Sunde K, Koster RW, Smith GB, et al. European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support. Resuscitation 2010;81(10):1305–52. [2] Ho AM. A technique of placing cuffed endotracheal tubes through in situ paediatric laryngeal mask airways. Anaesth Intensive Care 2014;42(3):330–2. [3] Henlin T, Michalek P, Tyll T, Hinds JD, Dobias M. Oxygenation, ventilation, and airway management in out-of-hospital cardiac arrest: a review. Biomed Res Int 2014;2014: 376–87. [4] Roth D, Schreiber W, Stratil P, Pichler K, Havel C, Haugk M. Airway management of adult patients without trauma in an ED led by internists. Am J Emerg Med 2013; 31(9):1338–42. [5] Timmermann A, Russo SG, Eich C, Roessler M, Braun U, Rosenblatt WH, et al. The out-of-hospital esophageal and endobronchial intubations performed by emergency physicians. Anesth Analg 2007;104:619–23. [6] Wesley K, Wesley K. Intubation alternative. JEMS 2014;39(3):23. [7] Wanderer JP, Ehrenfeld JM, Sandberg WS, Epstein RH. The changing scope of difficult airway management. Can J Anaesth 2013;60(10):1022–4. [8] Badawi R, Mohamed NN, Abd Al-Haq MM. Tips and tricks to increase the success rate of blind tracheal intubation through the Air-Q™ versus the intubating laryngeal mask airway Fastrach™. Egypt J Anaesth 2014;30(1):59–65. [9] Bashandy GMN, Boules NS. Air-Q the Intubating Laryngeal Airway: comparative study of hemodynamic stress responses to tracheal intubation via Air-Q and direct laryngoscopy. Egypt J Anaesth 2014;28(2):95–100. [10] Castle N, Pillay Y, Spencer N. Comparison of six different intubation aids for use while wearing CBRN-PPE: a manikin study. Resuscitation 2011;82(12):1548–52.

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