Open Access

EMT-led laryngeal tube vs. face-mask ventilation during cardiopulmonary resuscitation - a multicenter prospective randomized trial

  • Anna Fiala1,
  • Wolfgang Lederer1Email author,
  • Agnes Neumayr2,
  • Tamara Egger2,
  • Sabrina Neururer3,
  • Ernst Toferer1,
  • Michael Baubin1 and
  • Peter Paal4, 5
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine201725:104

https://doi.org/10.1186/s13049-017-0446-1

Received: 24 May 2017

Accepted: 4 October 2017

Published: 26 October 2017

Abstract

Background

Laryngeal tube (LT) application by rescue personnel as an alternate airway during the early stages of out-of-hospital cardiac arrest (OHCA) is still subject of debate. We evaluated ease of handling and efficacy of ventilation administered by emergency medical technicians (EMTs) using LT and bag-valve-mask (BVM) during cardiopulmonary resuscitation of patients with OHCA.

Methods

An open prospective randomized multicenter study was conducted at six emergency medical services centers over 18 months. Patients in OHCA initially resuscitated by EMTs were enrolled. Ease of handling (LT insertion, tight seal) and efficacy of ventilation (chest rises visibly, no air leak) with LT and BVM were subjectively assessed by EMTs during pre-study training and by the attending emergency physician on the scene. Outcome and frequency of complications were compared.

Results

Of 97 eligible patients, 78 were enrolled. During pre-study training EMTs rated efficacy of ventilation with LT higher than with BVM (66.7% vs. 36.2%, p = 0.022), but efficacy of on-site ventilation did not differ between the two groups (71.4% vs. 58.5%, p = 0.686). Frequency of complications (11.4% vs. 19.5%, p = 0.961) did not differ between the two groups.

Conclusions

EMTs preferred LT ventilation to BVM ventilation during pre-study training, but on-site there was no difference with regard to efficacy, ventilation safety, or outcome. The results indicate that LT ventilation by EMTs during OHCA is not superior to BVM and cannot substitute for BVM training. We assume that the main benefit of the LT is the provision of an alternative airway when BVM ventilation fails. Training in BVM ventilation remains paramount in EMT apprenticeship and cannot be substituted by LT ventilation.

Trial registration

ClinicalTrials.gov (NCT01718795).

Keywords

Airway managementCardiac arrestCardiopulmonary resuscitationLaryngeal tubePrehospital emergency medicine

Background

Supraglottic airways including the laryngeal tube (LT) enable rapid and effective ventilation in most cases [1]. Contrarily, conventional bag-valve-mask (BVM) ventilation and endotracheal intubation may be difficult, especially when caregivers have little experience.

The promoted simplicity in handling makes the LT an attractive device for airway management during cardiopulmonary resuscitation (CPR), even for healthcare providers with only basic training [2]. Success rates after short training on manikins were reported between 72% and 94% in emergency medical technicians (EMTs) [1, 35]. Kurola et al. observed that the LT may enable rapid and effective airway control as compared to BVM when used by inexperienced personnel [6]. The quick insertion of the LT may result in shorter hands-off intervals, increased chest compression fraction [7] and may consequently improve chest compression quality [8]. Muller et al. observed that mean tidal volume and mean minute volume were higher with LT ventilation than with BVM ventilation [8]. Ventilation by LT may be particularly advantageous when anatomic conditions, e.g. facial hair, edentulism, facial dysmorphia and obesity, make BVM ventilation difficult or even impossible.

Application of the LT by trained EMTs during CPR has been legal in Austria since 2010. We aimed to investigate subjectively assessed ease of handling (LT insertion, tight seal) and efficacy of ventilation (chest rises visibly, no air leak) with LT as compared to BVM ventilation as performed by EMTs after pre-study training and during CPR in OHCA.

Methods

Study design

The Institutional Review Board of the Medical University of Innsbruck approved this open prospective randomized multicenter study, which was conducted from September 2012 to February 2014. Airway management with EMT-led LT vs. BVM ventilation during out-of-hospital cardiac arrest (OHCA) was investigated in six physician-staffed emergency medical services (EMS) centers in Tyrol, Austria. In the case of presumed OHCA reported to the dispatch center, the ambulance and physician-staffed EMS closest to the emergency site were simultaneously dispatched. Due to the high density of ambulances EMTs frequently arrived on the scene first and provided basic life support until the emergency physician arrived. Only patients initially resuscitated by EMTs who completed their pre-study training were randomly assigned to airway management with either laryngeal tube suction – disposable (LTS-D, VBM Medizintechnik GmbH, Sulz a.N., Germany) or BVM (AMBU Spur II by Ambu A/S, Baltorpbakken 13, Ballerup, Denmark). All ambulances in the catchment area were equipped with an opaque envelope attached to each airway management set containing information on the randomization order. On scene, EMTs started basic life support (BLS, i.e. chest compression, ventilation according to randomization, and defibrillation if indicated) [2]. During BLS, chest compression and ventilation were continued at a ratio of 30:2 in both groups [2]. Efficacy of the EMT-guided ventilation was evaluated by the emergency physician as soon as he arrived at the scene by determining whether the chest rises visibly after each inflation without air leak. Data were recorded with mobile medical devices (Corpuls3, software ed.2.3, YOM 2011, G.Stemple GmbH, 86,916 Kaufering, Germany).

Inclusion criteria were: OHCA in patients ≥18 years of age. Exclusion criteria were: lack of consent of the involved EMT and/or emergency physician, emergency physician arriving at scene and starting airway management prior to arrival of the EMT, presumed airway obstruction, death of the patient before EMS arrival. It was agreed that if two attempts failed, the mode of airway management would be changed to the alternate ventilation technique. The study was designed according to intention to treat. A study manager regularly observed completeness of equipment and documentation.

Pre-study training

LT training followed the manufacturer’s recommendations (http://www.vbm-medical.de/cms/files/a5-1.0_06.08-de%2D-web%2D-.pdf). Similarly, BMV training was conducted according to international CPR guidelines [2]. Three months before study commencement, 203 EMTs completed a 2-h training session in LT insertion and ventilation, and a refresher course in BVM ventilation on manikins (Resusci Anne Advanced Skilltrainer CE, 151–20,033, YOM 2011, Laerdal Medical, 4002 Stavanger, Norway) at the Red Cross Academy in Innsbruck, Austria. At least three successful LT insertions with consequent sufficient ventilation (i.e. chest rises visibly after each ventilation without relevant air leak, evaluation performed by an emergency physician) were required to pass the training course.

Data collection

The data spread sheet was composed according to the Utstein Style Guidelines for OHCA [9], and the CONSORT 2010 guidelines [10]. Data collection was jointly performed by the attending EMT, the pre-hospital emergency physician, and the admitting hospital physician (Additional file 1). The EMT arriving first at the scene assessed quality of bystander CPR (location, depth and frequency of chest compressions, and whether ventilation was performed or not). The EMT recorded initial cardiac rhythm, interval between arrival on site and adequate ventilation, interval between CA (if witnessed) and arrival of EMT, interval between onset of CPR and arrival of emergency physicians (Additional file 1).

During pre-study training ventilation efficacy was subjectively assessed by EMTs using an on-line questionnaire (www.2ask.at; amundis Communications GmbH, Felix-Wankel-Str. 4, Constance, Germany). The primary study end-points were ease of handling and efficacy of ventilation assessed by EMTs. Secondary study end-points included ventilation attempts, efficacy of ventilation assessed by emergency physicians, and complications (Additional file 1).

Statistical analysis

The assumed null hypothesis for the primary study end-points was that ease of handling and efficacy of ventilation do not differ between LT and BVM ventilation. The sample size was calculated for an alpha-error of 0.05 and a power of 80% (beta-error of 0.2) to detect significant efficacy of ventilation in the LT group. A minimum of 25 applications in each group was deemed sufficient according to evaluation of the pre-study training. Categorical data were reported as frequencies and compared using the chi-square test. Ordinal data were reported as median and were analyzed using the Mann–Whitney U test or Spearman-Rho correlations. Results were deemed significant with a p value <0.05.

Results

Pre-study training assessment

All participating EMTs completed the questionnaire after training. Efficacy of LT ventilation was rated successful by most (66.7%) and regarded as more efficient (p = 0.022) than BVM ventilation (Table 1). According to the EMTs’ subjective assessment, ease of handling correlated with efficiency of ventilation when using the LT (p = 0.037). Ventilation problems were reported frequently in both groups (LT 44.4% vs. BVM 48.3%, p = 0.695). 86.1% of EMTs considered their LT training to be sufficient; 13.9% would have preferred additional training.
Table 1

Subjective EMT assessment of efficacy and ease of handling for LT and BVM ventilation after pre-study training using a 10-point scale regarding efficacy (1 = very low, 10 = very high) and ease of handling (1 = impossible, 10 = very easy)

 

LT group (n = 54)

BVM group (n = 58)

p-value

Efficacy, credits (n; %)

  

0.022

 1

14 (25.9)

13 (22.4)

 

 2

1 (1.9)

7 (12.1)

 

 3

0

4 (6.9)

 

 4

1 (1.9)

3 (5.2)

 

 5

0

2 (3.4)

 

 6

1 (1.9)

3 (5.2)

 

 7

0

5 (8.6)

 

 8

1 (1.9)

10 (17.2)

 

 9

6 (11.1)

5 (8.6)

 

 10

29 (53.7)

6 (10.3)

 

Ease of handling, credits (n; %)

  

0.171

 1

4 (7.4)

7 (12.1)

 

 2

2 (3.7)

1 (1.7)

 

 3

4 (7.4)

3 (5.2)

 

 4

0

4 (6.9)

 

 5

2 (3.7)

8 (13.8)

 

 6

0

7 (12.1)

 

 7

0

5 (8.6)

 

 8

8 (14.8)

10 (17.2)

 

 9

8 (14.8)

7 (12.1)

 

 10

24 (44.4)

5 (8.6)

 

On-site assessment

During the study period 469 calls of presumed OHCA (i.e. unresponsive person, no detectable breathing) were reported to the dispatch centre. 372 patients were not eligible to randomization (in 216 cases advanced life support was started either with EMTs lacking LT pre-training and/or with lacking EMT written consent). Ninety-seven cases were randomized (randomization rate 20.7%), and ultimately 78 patients included (inclusion rate 80.4%). Two patients were excluded because of incomplete data. Thus, 35 (46.1%) patients were ultimately allocated to the LT group and 41 (53.9%) to the BVM group (Fig. 1). There were no significant differences in patient characteristics or OHCA findings between the two groups (Table 2). In 26 (74.3%) patients the LT was successfully inserted and positioned on the first attempt. Efficient ventilation was confirmed by the attending emergency physician (LT 71.4% vs. BVM 58.5%, p = 0.686). We noted a tendency to lower oxygen saturation (first measurement after ROSC) with BVM ventilation. ROSC occurred in 16 patients (21.1%).
Fig. 1

Flow Diagram (Consort 2010) of patient enrolment, randomization, allocation, and analysis

Table 2

Patient characteristics and cardiac arrest findings on-site in thirty-five patients with laryngeal tube ventilation and in forty-one patients with bag valve mask ventilation

 

LT group (n = 35)

BVM group (n = 41)

p-value

Patient characteristics

 Male gender (n; %)

23; 65.7

26; 63.4

0.811

 Age (year; SD)

69.1 ± 17.4

71.4 ± 13.7

0.554

 Witnessed arrest (n; %)

11; 31.4

15; 36.6

0.993

 Hospital discharge (n; %)

1; 2.9

1; 2.4

0.848

Intervals

 Call - CPR onset (median; IQR)

3 (1; 9.5)

4 (1; 7)

0.885

 Call - effective ventilation (min; ±SD)

10.1 ± 8.0

8.9 ± 5.8

0.705

 Call - hospital arrival (min; ±SD)

68.4 + 50.5

53.1 + 13.3

0.953

Basic Life Support

 Bystander CPR (n; %)

18; 51.4

13; 31.7

0.169

 Effective CPR (n; %

11; 31.4

6; 14.6

0.095

Advanced Life Support

 Effective ventilation (n; %)

25; 71.4

24; 58.5

0.686

 Tracheal intubation (n; %)

11; 31.4

9; 22.0

0.374

 First CO2 (mm Hg; SD)

33.0 ± 16.9

23.5 ± 19.6

0.12

First documented ECG rhythm

  

0.606

 Asystole (n; %)

20; 57.1

17; 41.5

 

 Pulse-less electrical activity (n; %)

6; 17.1

7; 17.0

 

 pVT/VF (n; %)

8; 22.9

11; 26.8

 

ROSC (n; %)

9; 25.7

7; 17.1

0.478

 Heart rate (mean, ±SD)

87.2 ± 23.1

73.0 ± 38.6

0.375

 Systolic blood pressure (mean, ±SD)

122.4 ± 39.2

94.6 ± 28.8

0.185

 O2 saturation (mean, ±SD)

91.1 ± 7.9

86.8 ± 8.7

0.272

Complications

  

0.961

 Aspiration (n)

0

1

 

 Airway bleeding (n)

1

1

 

 Regurgitation (n)

4

7

 

BVM bag valve mask, CO 2 carbon dioxide, CPRcardiopulmonary resuscitation, ECG Electrocardiography, IQR interquartile range, LT laryngeal tube, n number, O 2 oxygen, pVT pulseless ventricular tachycardia, ROSCreturn of spontaneous circulation, SD standard deviation, VF ventricular fibrillation

On-site complications comprised aspiration in one patient (BVM group) and injuries to the mucosal membrane indicated by blood stain on the device, one in the LT group and one in the BVM group.

Discussion

EMTs preferred LT ventilation over BVM ventilation in the pre-study training, but on-site assessment regarding ease of handling and efficacy, frequency of complications and outcome showed no differences between the two methods. We prospectively studied ease of handling and efficacy of LT and BVM ventilation performed by EMTs during pre-study training. The standardized training program allowed comparison of LT and BVM airway management and ventilation in real life OHCA patients. However, data acquisition was prone to incomplete recording as compared to findings of previous experimental studies. As simulated conditions may substantially differ from real CPR situations, our prospective study design allowed subjective assessment of ventilation by EMTs after pre-study training and objective evaluation of ventilation by emergency physicians during real OHCA.

After training, 66.7% of EMTs in our study appraised LT ventilation as being highly efficient. This corresponds with findings made in other studies of LT ventilation administered by EMTs and nurses showing success rates between 72 and 94% [1, 35, 11]. Although most EMTs in our study had only basic experience (fewer than ten LT insertions), they more often cited good ease of handling and fewer problems as compared to BVM. Roth et al. reported that LT ventilation in real CPR was more successful than BVM ventilation (93% vs. 30%) [1]. In our study the attending emergency physicians confirmed efficient ventilation by EMTs in cases for LT (71.4%) as well as for BVM (58.5%; p = 0.686). Presumably, the pre-study refresher in BVM ventilation may have had an impact on the frequency of efficient BVM ventilation.

After training, EMTs regarded LT ventilation as superior to BVM ventilation; only 13.9% of EMTs considered additional training with LT insertion and ventilation necessary. However, EMTs frequently reported difficulties with ventilation in both groups during pre-study training. Sunde et al. observed a high number of insertion-related problems with LT ventilation [12]. The authors concluded that promising results in manikin studies may not be applicable to real-life CPR [12]. We assume that high expectations for the LT may create a subjective reality. Perceptions of advantage and disadvantage may influence performance and efficacy beliefs in a competitive situation [13]. Applied to our pre-study results this would mean that expectations of EMTs for the LT may eventually lead them to behave and achieve in ways that confirm their expectations.

In most patients on site, effective ventilation was provided within the first 10 min of OHCA. Within this interval airway management is not expected to substantially influence outcome. Iwami et al. reported that in patients with CA of presumed cardiac origin chest compression only (and defibrillation, if indicated) is superior to combined respiratory and cardiac resuscitation within the first 5 min of CPR [14]. Maignan et al. compared 41 cases with intermittent chest compressions in the BVM group to 41 cases with continuous chest compressions in the LT group. Airway management with the LT was associated with a 27% increase in the chest compression fraction and significantly reduced hands-off intervals but survival to discharge did not differ significantly between the two groups [7]. We doubt that increased chest compression fraction can be achieved with the comparatively low LT leak pressure. An estimated leak pressure of approximately 36 cm H2O was reported for LT ventilation [15]. Therefore, in our study intermittent chest compression and ventilation were continued at a ratio of 30:2 after LT insertion as we expected low LT leak pressure to interfere with continuous chest compression and simultaneous ventilation.

We encountered only one airway bleeding (blood stain on the device) and no case of aspiration in the LT group. However, factors associated with unsuccessful LT ventilation in the prehospital setting are numerous including incorrect placement of the tube in the trachea or in the pharynx, mucosa swelling of the tongue and throat and unrecognized airway obstruction [7, 16, 17]. Incorrect LT placement may cause gastric inflation, regurgitation and massive pulmonary aspiration. Dengler et al. recommended that LTS should be used in all cases of emergency airway management [16].

Tanabe et al. reported in a nation-wide study that prehospital use of supraglottic airway devices was associated with poorer neurological outcome as compared to tracheal intubation [18]. Results from animal research indicate that carotid blood flow in the low-perfusion state during CPR is further diminished by pressure on the carotid arteries from inflated LT cuffs [19].

The time may be nearing when BVM ventilation will lose its prominence as the standard ventilation technique during basic life support in favor of supraglottic airway devices [20]. However, LT ventilation during cardiac arrest is not a strikingly simple solution. Currently, training in BVM ventilation remains paramount in EMT apprenticeship.

Limitations of our study arise from the fact that the study was conducted in a selected sample of OHCA patients collected from six different centers. The study design determined the enrollment of cases with OHCA, where one of 203 trained EMTs had started CPR and airway management before arrival of the emergency physician. This offers considerable risk of a selection bias as EMTs without training were not allowed to participate in the study, and whenever the emergency physician arrived first he initiated ALS airway management. As EMTs do not intubate OHCA patients in our county, we did not evaluate tracheal intubation by EMTs for efficacy and ease of handling. Of the EMTs 13.9% would have preferred additional training after the pre-study training. Procedural bias from anticipated pressure to perform might have induced some of the EMTs to not participate. Correlations between mode of ventilation and survival to discharge were not calculated as we do not know the various clinical aspects that might have influenced the outcome.

Conclusions

EMTs preferred LT ventilation to BVM ventilation during pre-study training, but on site no difference was seen in efficacy, ventilation safety or outcome. The results indicate that LT ventilation by EMTs during OHCA is not superior to BVM ventilation and that LT cannot substitute for BVM training. We assume that the main benefit of the LT is the provision of an alternative airway when BVM ventilation fails. Training in BVM ventilation remains paramount in EMT apprenticeship and cannot be substituted by LT ventilation.

Abbreviations

BVM: 

Bag valve mask

CPR: 

Cardiopulmonary resuscitation

ECG: 

Electrocardiography

EMS: 

Emergency medical services

EMT: 

Emergency medical technicians

ERC: 

European Resuscitation Council

LT: 

Laryngeal tube

OHCA: 

Out-of-hospital cardiac arrest

pVT: 

Pulseless ventricular tachycardia

ROSC: 

Return of spontaneous circulation

VF: 

Ventricular fibrillation

Declarations

Acknowledgements

We thank everyone involved in the study, in particular the EMTs from EMS Tyrol (Rotes Kreuz Tirol gem. Rettungsdienst GmbH), the emergency physicians and the medical personnel from the emergency departments of Innsbruck Medical University Hospital, Hall State Hospital and Kufstein County Hospital.

Funding

The LTs used in this study were provided free of charge by VBM Medizintechnik GmbH. No grants were received. The authors have no conflict of interest to declare.

Availability of data and materials

All data generated or analyzed during the study are included in this published article.

Authors’ contributions

Conceptualization, design and conduction of the study were undertaken by WL, PP, AN, ET and MB. Airway management training of emergency medical technicians was performed by ET and AF. TE allocated data. AN, SN, TE and WL analyzed data. AF, WL and PP wrote the manuscript and the other authors performed revisions. All authors read and approved the final manuscript.

Ethics approval and consent to participate

The study was approved by the Ethics Committee of the Medical University of Innsbruck, Austria (AN4355–300/4.15).

Consent for publication

Consent of relatives was planned to be sought “post hoc” after enrolment and treatment on site but was not necessary during the study. Patients’ informed written consent in those who survived with good cerebral performance was planned to be obtained during recovery. Written informed consent from EMTs was obtained after successful training and from EMS physicians after general information was provided at the centers. Written consent of the EMS was given by the designated Medical Director. Comprehensive insurance coverage for patients and EMTs was provided by Innsbruck Medical University Hospital.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Anesthesiology and Critical Care Medicine, Medical University of Innsbruck
(2)
Medical University of Innsbruck
(3)
Department of Medical Statistics, Informatics and Health Economics, Medical University of Innsbruck
(4)
Department of Anaesthesiology and Intensive Care Medicine, Hospitallers Brothers Hospital, Teaching Hospital of the Paracelsus Private Medical University Salzburg
(5)
Barts Heart Centre, William Harvey Research Institute, Barts & The London School of Medicine & Dentistry, Queen Mary University of London

References

  1. Roth D, Hafner C, Aufmesser W, Hudabiunigg K, Wutti C, Herkner H, Schreiber W. Safety and feasibility of the laryngeal tube when used by EMTs during out-of-hospital cardiac arrest. Am J Emerg Med. 2015;33(8):1050–5.View ArticlePubMedGoogle Scholar
  2. Koster RW, Baubin MA, Bossaert LL, Caballero A, Cassan P, Castrén M, Granja C, Handley AJ, Monsieurs KG, Perkins GD, Raffay V, Sandroni C. European resuscitation council guidelines for resuscitation 2010 section 2. Adult basic life support and use of automated external defibrillators. Resuscitation. 2010;81(10):1277–92.View ArticlePubMedGoogle Scholar
  3. Länkimäki S, Alahuhta S, Kurola J. Feasibility of a laryngeal tube for airway management during cardiac arrest by first responders. Resuscitation. 2013;84(4):446–9.View ArticlePubMedGoogle Scholar
  4. Russi CS, Wilcox CL, House HR. The laryngeal tube device: a simple and timely adjunct to airway management. Am J Emerg Med. 2007;25(3):263–7.View ArticlePubMedGoogle Scholar
  5. Heuer JF, Barwing J, Eich C, Quintel M, Crozier TA, Roessler M. Initial ventilation through laryngeal tube instead of face mask in out-of-hospital cardiopulmonary arrest is effective and safe. Eur J Emerg Med. 2010;17(1):10–5.View ArticlePubMedGoogle Scholar
  6. Kurola J, Harve H, Kettunen T, Laakso JP, Gorski J, Paakkonen H, Silfvast T. Airway management in cardiac arrest - comparison of the laryngeal tube, tracheal intubation and bag-valve mask ventilation in emergency medical training. Resuscitation. 2004;61(2):149–53.View ArticlePubMedGoogle Scholar
  7. Maignan M, Koch FX, Kraemer M, Lehodey B, Viglino D, Monnet MF, Pham D, Roux C, Genty C, Rolland C, Bosson JL, Danel V, Debaty G. Impact of laryngeal tube use on chest compression fraction during out-of-hospital cardiac arrest. A prospective alternate month study. Resuscitation. 2015;93:113–7.View ArticlePubMedGoogle Scholar
  8. Müller JU, Semmel T, Stepan R, Seyfried TF, Popov AF, Graf BM, Wiese CH. The use of the laryngeal tube disposable by paramedics during out-of-hospital cardiac arrest: a prospectively observational study (2008–2012). Emerg Med J. 2013;30(12):1012–6.View ArticlePubMedGoogle Scholar
  9. Cummins RO, Chamberlain D, Hazinski MF, Nadkarni V, Kloeck W, Kramer E, Becker L, Robertson C, Koster R, Zaritsky A, Ornato JP, Callanan V, Allen M, Steen P, Connolly B, Sanders A, Idris A, Cobbe S. Recommended guidelines for reviewing, reporting, and conducting research on in-hospital resuscitation: the in-hospital “Utstein style”. American Heart Association. Ann Emerg Med. 1997;29(5):650–79.View ArticlePubMedGoogle Scholar
  10. Schulz KF, Altman DG, Moher D, CONSORT Group. CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials. Int J Surg. 2011;9(8):672–7.View ArticlePubMedGoogle Scholar
  11. Asai T, Moriyama S, Nishita Y, Kawachi S. Use of the laryngeal tube during cardiopulmonary resuscitation by paramedical staff. Anesthesia. 2003;58:393–4.View ArticleGoogle Scholar
  12. Sunde GA, Brattebo G, Odegarden T, Kjernlie DF, Rodne E, Heltne JK. Laryngeal tube use in out-of-hospital cardiac arrest by paramedics in Norway. SJTREM. 2012;20:84.PubMedPubMed CentralGoogle Scholar
  13. Ganzach Y, Stirin K, Pazy A, Eden D. The joint effect of expectations and performance on efficacy beliefs. Personal Individ Differ. 2016;88:51–6.View ArticleGoogle Scholar
  14. Iwami T, Kitamura T, Kawamura T, Mitamura H, Nagao K, Takayama M, Seino Y, Tanaka H, Nonogi H, Yonemoto N, Kimura T, Japanese Circulation Society Resuscitation Science Study (JCS-ReSS) Group. Chest compression-only cardiopulmonary resuscitation for out-of-hospital cardiac arrest with public-access defibrillation: a nationwide cohort study. Circulation. 2012;126(24):2844–51.View ArticlePubMedGoogle Scholar
  15. Ocker H, Wenzel V, Schmucker P, Steinfath M, Dörges V. A comparison of the laryngeal tube with the laryngeal mask airway during routine surgical procedures. Anesth Analg. 2002;95(4):1094–7.View ArticlePubMedGoogle Scholar
  16. Dengler V, Wilde P, Byhahn C, Mack MG, Schalk R. Prehospital airway management of laryngeal tubes. Should the laryngeal tube S with gastric drain tube be preferred in emergency medicine? Anaesthesist. 2011;60(2):135–8.View ArticlePubMedGoogle Scholar
  17. Martin-Gill C, Prunty HA, Ritter SC, Carlson JN, Guyette FX. Risk factors for unsuccessful prehospital laryngeal tube placement. Resuscitation. 2015;86:25–30.View ArticlePubMedGoogle Scholar
  18. Tanabe S, Ogawa T, Akahane M, Koike S, Horiguchi H, Yasunaga H, Mizoguchi T, Hatanaka T, Yokota H, Imamura T. Comparison of neurological outcome between tracheal intubation and supraglottic airway device insertion of out-of-hospital cardiac arrest patients: a nationwide, population-based, observational study. J Emerg Med. 2013;44(2):389–97.View ArticlePubMedGoogle Scholar
  19. Segal N, Yannopoulos D, Mahoney BD, Frascone RJ, Matsuura T, Cowles CG, McKnite SH, Chase DG. Impairment of carotid artery blood flow by supraglottic airway use in a swine model of cardiac arrest. Resuscitation. 2012;83(8):1025–30.View ArticlePubMedGoogle Scholar
  20. Paal P, Gruber E, Beikircher W, Herff H, Brugger H. Sunset of bag-valve mask and rise of supra-glottic airway ventilation devices during basic life support. Resuscitation. 2010;81(11):1594–5.View ArticlePubMedGoogle Scholar

Copyright

© The Author(s). 2017

Advertisement