RESPIRATION AND THE AIRWAY. Editor s key points

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1 British Journal of Anaesthesia 108 (1): (2012) Advance Access publication 27 October doi: /bja/aer327 RESPIRATION AND THE AIRWAY Simulating face-to-face tracheal intubation of a trapped patient: a randomized comparison of the LMA Fastrach TM, the GlideScope TM, and the Airtraq TM laryngoscope R. Amathieu 1,2, J. Sudrial 1,2, W. Abdi 1,2, D. Luis 1,2, H. Hahouache 1,2, X. Combes 3,4 and G. Dhonneur 1,2 * 1 Anaesthesia and Intensive Care Unit Department, Jean Verdier University Hospital of Paris, Bondy, France 2 Paris 13 University School of Medicine, Bobigny, France 3 Pre Hospital Medical Emergency Unit, Henri Mondor University Hospital of Paris, Créteil, France 4 Paris 12 University School of Medicine, Bobigny, France * Corresponding author. gilles.dhonneur@jvr.aphp.fr Editor s key points Not many studies have evaluated the performance of airway devices in a trapped patient. The authors compared LMA Fastrach TM, Airtraq TM laryngoscope, and GlideScope TM in a simulated trapped patient. The Airtraq TM laryngoscope achieved better and quicker visualization of the larynx and success rate for intubation. The study shows the usefulness of the Airtraq TM laryngoscope in a scenario of a trapped patient. Background. We undertook a prospective randomized comparison of the LMA Fastrach TM, Airtraq TM laryngoscope, and GlideScope TM used for face-to-face tracheal intubation simulated to mimic an entrapped patient. Methods. Thirty senior emergency medicine physicians were trained in the use of the LMA Fastrach TM, GlideScope TM, and Airtraq TM laryngoscope with a standard airway trainer manikin (control). Participants were then asked to perform tracheal intubation in two difficult situations simulated on a difficult airway management manikin wearing a cervical collar. In Situation 1, the manikin was in the supine position with a difficult airway caused by stiffening the cervical spine. In Situation 2, the manikin was positioned to simulate face-to-face tracheal intubation. We measured intubation times, success rates for tracheal intubation, and the difficulty of tracheal intubation. Values are means (SD). Results. In control and Situation 1, tracheal intubation details were similar. In Situation 2, face-to-face tracheal intubation success rate was increased with the Airtraq TM (100%), when compared with that of the GlideScope TM (70%, P,0.05) and LMA Fastrach TM (83%, P,0.05). Face-to-face tracheal intubation was less difficult (visual analogue scale: 0 100) with the Airtraq TM 11 (6) when compared with the GlideScope TM [33 (14) s, P,0.01)] and LMA Fastrach TM [22 (21) s, P,0.01]. The face-to-face tracheal intubation time was shorter with the Airtraq TM 14 (6) s than with the GlideScope TM [27 (18) s, P,0.01] and Fastrach TM [28 (10) s, P,0.01]. Conclusions. The Airtraq TM laryngoscope was superior to both the GlideScope TM and LMA Fastrach TM during simulated face-to-face difficult tracheal intubation. Keywords: airway; equipment, airway; equipment, laryngoscope; tracheal intubation Accepted for publication: 16 August 2011 Resuscitating victims of road traffic collisions in the prehospital environment is sometimes difficult because of limited access to the patient. Managing the airways is particularly challenging, especially if the patients are entrapped. When attempts using conventional tracheal intubation techniques have failed to establish and maintain adequate oxygenation, tracheal intubation may be needed, with the patient still trapped in a sitting position with difficult-to-access airways. The Macintosh laryngoscope is particularly difficult to use in these circumstances because most patients would be placed in a cervical collar. 1 Laryngeal mask airways 2 and more particularly the intubating laryngeal mask airway Fastrach TM (LMA Fastrach TM, SEBAC, Pantin, France) have been used in such patients as a primary airway to restore ventilation and to blindly intubate the trachea. 3 However, the success rate for blind tracheal intubation through the LMA Fastrach TM may be lowered by the fact that manoeuvres described to improve tracheal intubation performance cannot be used in patients with suspected or simulated cervical spine injury. 34 Interestingly, there has been a report in & The Author [2011]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please journals.permissions@oup.com

2 Video-assisted tracheal intubation which an indirect optical laryngoscope proved to be more effective than the Macintosh laryngoscope in intubating the trachea of a simulated patient confined in a driver s seat of a car. 1 Moreover, modern optical devices using innovative blades shaped differently from those of the Macintosh laryngoscope are now available for tracheal intubation under direct vision without excessive cervical spine movements. 56 Devices such as the Airtraq TM (VYGON, Ecouen, France) laryngoscope and the GlideScope TM (VERATHON, Schiltigheim, France) are effective when tracheal intubation is difficult, 78 but have not been evaluated in patients with a difficult-to-access airway. They are both equipped with a portable video monitor system including a battery, so we hypothesized that these devices could improve face-to-face tracheal intubation especially when the patient is trapped in the sitting position with limited access. We undertook a prospective randomized comparison of faceto-face tracheal intubation performance, using the LMA Fastrach TM,Airtraq TM laryngoscope, and GlideScope TM and a difficult airway management manikin to simulate a trapped patient in the sitting position with restricted access to the airway. Methods After receiving local research Ethics Committee s approval, written informed consent was obtained from 30 senior emergency medicine physicians attending a specialized airway management diploma (Excellence Level in Airway Management EXCLAM, Paris 13 School of Medicine). Participants, education, and training All participants familiar with the LMA Fastrach TM, but strictly naïve to the use of new video-assisted tracheal intubation devices, received 2 h of oral instruction on the use of the Airtraq TM laryngoscope and the GlideScope TM, with a particular focus on the use of a malleable stylet, and shaping of the tracheal tube to facilitate intubation with GlideScope TM.Each participant watched video demonstrations with the LMA Fastrach TM, Airtraq TM laryngoscope, and GlideScope TM intubation techniques performed on a standard manikin and in the operating theatre. After these presentations, the participants were requested to practise the use of each device using a standard training manikin (LAERDAL, Airway Management Trainer TM, Limonest, France). Participants had unlimited access to manikin training. The participants were supervised by five board-certified anaesthesiologists and skilled in the clinical use of the LMA Fastrach TM and both video-controlled tracheal intubation devices. When using the LMA Fastrach TM, the participants were asked to demonstrate their ability to ventilate the lungs before tracheal intubation manoeuvres were attempted. Instructors considered that the learning process of the LMA Fastrach TM, Airtraq TM laryngoscope, and GlideScope TM was complete when the participants were able to carry out successfully at least 10 timed tracheal intubations of similar duration (difference between the longest and the shortest intubation time of 5 s). Participants were then informed of the object of the study, which was Fig 1 The difficult airway management manikin SimMan TM was positioned vertically simulating a trapped patient in a sitting position with difficult-to-access airways requiring face-to-face tracheal intubation (Situation 2). to test their ability to perform difficult tracheal intubation using manikin simulation. Study design A difficult airway was simulated with two difficult airway simulator manikins (LAERDAL, AirMan TM ) placed in different rooms. The first one was placed on a stretcher in a standard supine position (Situation 1). A difficult airway was simulated by applying a cervical collar and restricting cervical spine movement. The second manikin, also wearing a cervical collar, was fixed vertically simulating a trapped patient in a sitting position with difficult-to-access (Situation 2) airways requiring face-to-face tracheal intubation (Fig. 1). The order of the situations was pre-set. Each participant moved from Situation 1 to Situation 2. In each situation, the order of use of the tracheal intubation devices was randomized for each participant using sealed envelopes. After the experiment, the participants were asked to discuss their experience and describe the advantages and limitations associated with LMA Fastrach TM and video-assisted intubation devices during face-to-face tracheal intubation attempts. Outcome variables The primary endpoints were intubation times and overall success rate of tracheal intubation. We defined intubation time as the time elapsing between the intubating devices entering the oral cavity until viewing the tubes 7.5 size (Covidien, Elancourt, France, for the Airtraq TM laryngoscope and GlideScope TM, and LMAc, SEBAC, Pantin, France, for the LMA Fastrach TM ) entering the trachea (visual judgement by the supervisor). We defined a failed intubation as one in which the trachea was not intubated within 1 min; however, the 141

3 Amathieu et al. timing of the manoeuvre was continued until tracheal intubation was achieved and tracheal intubation success rate at 2 min was calculated. Additional endpoints were: the number of oesophageal intubations, a score of the quality of the laryngeal view measured as the percentage of glottis opening visible on the video monitor 9 ranging from 0% (no part of the glottis is visible) to 100% (full view of glottis opening), and the difficulty of tracheal intubation rated using a visual analogue scale from 0 (very simple) to 100 (impossible). Details and outcomes of the three last tracheal intubation attempts performed with each device at the end of the training programme with the standard airway management manikin were taken as control data (control) and compared with those of Situations 1 and 2. Statistical analyses We have measured a mean (SD) face-to-to face tracheal intubation time of 21 (12) s with the GlideScope TM during simulated difficult intubation scenarios when performed by the five instructors of the present trial. Based upon this result, and that of a previous comparative manikin study, 10 showing that the Airtraq TM laryngoscope allowed a marked reduction in tracheal intubation duration in difficult intubation simulation, we hypothesized that it would reduce the mean face-to-face tracheal intubation time by 50%, mainly because it is a channelled laryngoscope allowing tracheal intubation without the need of piloting the tracheal tube. We calculated that 30 intubations performed with the Airtraq TM laryngoscope and the GlideScope TM would be sufficient to prove our hypothesis with a 90% power at a significance level of 0.05 (two-sided test). We used a x 2 test to compare the overall rate of successful tracheal intubation and oesophageal intubation. Wilcoxon s tests were used to compare intubation times and tracheal intubation analogue scale measurements. A Student s t-test was used to compare the quality of the laryngeal view. Statistics were computed using XLSTAT TM 2008 software (Addinsoft, Paris, France). A P-value of,0.05 was considered significant. Results Thirty senior emergency medicine physicians (M/F: 17/13, mean age 37 yr, with a median of 7 yr medical experience as a senior) volunteered to take part in the study. Participants attempted a total of 90 tracheal intubations. Outcomes of tracheal intubation attempts are presented in Table 1. There was no significant difference in outcomes between Situation 1 and control for all the devices. Intubation time, score of laryngeal view quality, and success rate of tracheal intubation at 1 min were significantly changed with the three tracheal intubation devices in Situation 2 when compared with Situation 1. Tracheal intubation difficulty with the GlideScope TM, but not with the Airtraq TM and the LMA Fastrach TM, was significantly increased in Situation 2 when compared with Situation 1. In Situation 2, face-to-face tracheal intubation success rate at 1 min was increased, intubation time was shorter, and tracheal intubation was less difficult when the Airtraq TM laryngoscope was used, compared with the GlideScope TM and LMA Fastrach TM [100 vs 70 and 83%, P,0.05; 14 (6) vs 27 (18) and 28 (10) s, P,0.01; 11 (6) vs 33 (14) and 22 (21), P,0.01, respectively]. After 2 min of attempted intubation, tracheal intubation was achieved in all cases. Oesophageal intubation occurred in a few instances, only with the LMA Fastrach TM. All the participants experienced difficulties in piloting the tracheal tube through the pharynx while intubation was attempted with the GlideScope TM. Discussion We showed that face-to-face tracheal intubation was possible with the LMA Fastrach TM, the Airtraq TM, and the GlideScope TM. We found that senior emergency physicians obtained successful face-to-face tracheal intubation more rapidly with the Airtraq TM laryngoscope than with the GlideScope TM and LMA Fastrach TM. Face-to-face tracheal intubation was more difficult than conventional intubation with the LMA Fastrach TM and GlideScope TM, but not with the Airtraq TM laryngoscope. We found that face-to-face tracheal intubation is not difficult in simulated conditions with the new-generation video-assisted airway devices. After a short learning process, all senior emergency medicine physicians skilled with conventional tracheal intubation technique were able to reach a 100% success rate for tracheal intubation on a standard manikin (control) and a 100% success rate within 2 min in the difficult face-to-face tracheal intubation scenario (Situation 2). Our findings support the previous reports of a short learning time and good tracheal intubation performance with these new video-assisted devices especially in the case of difficult airway scenarios. We chose to study the GlideScope TM and Airtraq TM laryngoscope, from the many modern optical devices available for comparison for several reasons. First, both devices do not cause much cervical spine movement during tracheal intubation manoeuvres due to a particular blade, whose shape is different from that of the Macintosh laryngoscope. 512 Secondly, both devices are equipped with a portable video monitor system, which can be placed anterior to the patient during face-to-face tracheal intubation. Thirdly, with other optical devices where the screen monitor is attached to the handle of the laryngoscope, the face-to-face tracheal intubation scenario is not possible because of limited screen orientation capability. The face-to-face tracheal intubation scenario allowed reasonable comparison of tracheal intubation performance of the two video-assisted tracheal intubation devices. Indeed, the Situation 1 difficult intubation scenario did not affect tracheal intubation outcomes when compared with control conditions. On the other hand, tracheal intubation results were affected by the changes in the relative position of the patient and the operator imposed in Situation 2. Intubation times and difficulty scores were greater with all tracheal intubation devices during face-to-face tracheal 142

4 Video-assisted tracheal intubation Table 1 Outcomes of intubation attempts using the LMA Fastrach TM, GlideScope, and Airtraq TM laryngoscope. Score of laryngeal view quality (0%¼no part of the glottis is visible, to 100%¼full view of glottis opening); VAS, visual analogue scale of tracheal intubation difficulty (0¼very simple, 100 impossible). Intubation time: time duration elapsing between the intubating devices entering the oral cavity until viewing the tube entering the trachea. Control: tracheal intubation performed at the end of the training on a standard manikin (Airway Management Trainer TM ). Situation 1: tracheal intubation performed on a difficult airway simulator manikin (AirMan TM ) wearing a cervical collar. Situation 2: face-to-face tracheal intubation performed on a difficult airway simulator manikin (AirMan TM ), wearing a cervical collar, fixed vertically simulating a trapped patient in a sitting position with difficult-to-access airways. Data are reported as numbers or as mean (SD). 1 P,0.05 when compared with Situation 1; *P,0.05 when compared with GlideScope TM ; 8P,0.05 when compared with LMA Fastrach TM Primary and secondary endpoints Airways LMA Fastrach TM (n530) GlideScope TM (n530) Airtraq TM (n530) Intubation times (s) Control 19 (11) 13 (9)8 8 (3)* Situation 1 18 (10) 15 (6) 10 (4)* Situation 2 29 (10) 1 27 (18) 1 14 (6) 1 * Score of laryngeal view quality (%) Control 100 ( ) 100 ( ) Situation ( ) 100 ( ) Situation 2 81 (11) 1 94 (4) 1, * Tracheal intubation difficulty (VAS, 0 100) Control 19 (10) 19 (6) 7 (6)*, 8 Situation 1 20 (12) 21 (11) 9 (6)*, 8 Situation 2 22 (11) 33 (14) 1, 8 11 (6)*, 8 Success of tracheal intubation at 1 min (%) Control Situation Situation * Oesophageal intubation (n) Control Situation Situation intubation. However, face-to-face tracheal intubation had little influence on the intubation time and on the success rate for tracheal intubation with the Airtraq TM laryngoscope. This is certainly an important result of the present study. Indeed, we hypothesized that the Airtraq TM laryngoscope would be easier to use in the case of face-to-face tracheal intubation because insertion of the tracheal tube in the trachea was simplified due to the lateral channel which guides the tube towards the glottis. Of interest, we have demonstrated that the LMA Fastrach TM promoted a high success rate for the first-attempt face-to-face blind tracheal intubation. Although face-to-face intubation times with the LMA Fastrach TM were similar to those of the GlideScope TM, the perceived difficulty of face-to-face tracheal intubation was lower with the LMA Fastrach TM than with the GlideScope TM. This result is not surprising since the manipulations of the LMA Fastrach TM were not affected by the relative position of the operator and the manikin. All the participants placed the laryngeal mask and pushed the tube with the dominant hand, and manipulated the metallic handle of the LMA Fastrach TM with the nondominant hand in Situations 1 and 2 (Fig.2A). On the contrary, during face-to-face tracheal intubation with the GlideScope TM, six participants held the handle with the dominant hand and manipulated the shaped tube with the other one. After failed tracheal access, all of these subjects changed their mind and manipulated the tube with the dominant hand (Fig. 2B). Although difficulty in tracheal tube insertion has already been demonstrated with most un-channelled tracheal intubation video-assisted devices, these changes of the habits acquired with the Macintosh laryngoscope and during the learning process of GlideScope TM have certainly contributed to a prolonged intubation time and lower success rate at 1 min, resulting in a greater perceived overall difficulty of face-to-face tracheal intubation. The individual debriefing of the participants revealed that difficulty in face-to-face tracheal intubation with GlideScope TM mainly resulted from more difficult laryngeal visualization and more difficulty with tube insertion. Interestingly, face-to-face tracheal intubation with the Airtraq TM laryngoscope only required a reversal of the role of hands. Indeed, in all participants, the airway was positioned and maintained stable with the right hand, and the tracheal tube was manipulated with the left hand (Fig. 2C). This simplicity of Airtraq TM laryngoscope use has influenced our results that showed that the Airtraq TM laryngoscope is an efficient video-assisted tracheal intubation device to perform face-to-face tracheal intubation. 143

5 Amathieu et al. Fig 2 Demonstrations of face-to-face tracheal intubation technique with the LMA Fastrach TM (A), the GlideScope TM (B), and the Airtraq TM laryngoscope (C). Our study has several limitations. First, an airway manikin does not reproduce a real-life prehospital tracheal intubation environment in severely injured patients. Therefore, our results may not be directly extended to clinical prehospital situations, particularly those where the traumatized patient has bloody secretions in the pharynx. Secondly, although, the Airtraq TM laryngoscope has been successfully used for face-to-face tracheal intubation in the prehospital environment by one of the instructors in the present study, we believe that blind devices such as the LMA Fastrach TM certainly have advantages in some settings such as massive bleeding due to facial trauma. In such circumstances where oropharyngeal suction of blood or a material may be ineffective in clearing the airways, video-assisted tracheal intubation devices might be less useful, whereas the LMA Fastrach TM may assist haemostasis, restore ventilation, and allow blind tracheal intubation. In the present trial, all participants facing the manikin placed in the sitting position restored ventilation and secured the airway using the LMA Fastrach TM within a mean of 30 s delay after its insertion in the oral cavity. Thirdly, because of the design, we could not blind our study. However, we believe that this did not affect our results, as we selected clear and robust endpoints (intubation times and success rate) to power our study. Finally, we have used the Airtraq TM laryngoscope linked to a video monitor system. In a real situation, when access to the patient head is difficult and restricted, it would be probably difficult for an intubator to see through the Airtraq TM itself, thus reducing the usefulness of this airway when not associated with its video monitor system. In conclusion, the Airtraq TM laryngoscope and the GlideScope TM allowed face-to-face tracheal intubation. The Airtraq TM laryngoscope clearly demonstrated advantages over the GlideScope TM with shorter intubation time and increased tracheal intubation success at 1 min. Although the LMA Fastrach TM demonstrated a high face-to-face blind intubation first-attempt success rate, we believe that new video-assisted tracheal intubation devices (Airtraq TM laryngoscope; GlideScope TM ) could be used to save lives by allowing on the scene early face-to-face tracheal intubation in trapped patients. Acknowledgements The authors acknowledge Gordon Blair Drummond, MD, PhD (Senior Lecturer from the Department of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary, Edinburgh, Scotland), for his very helpful contribution to the editing process of the manuscript. Declaration of interest G.D. is a consultant and member of the Laryngeal Mask Company medical advisory board. Funding All funding was from departmental sources. References 1 Asai T. Tracheal intubation with restricted access: a randomised comparison of the Pentax-Airway Scope and Macintosh laryngoscope in a manikin. Anaesthesia 2009; 64: Hulme J, Perkins GD. Critically injured patients, inaccessible airways, and laryngeal mask airways. Emerg Med J 2005; 22: Mason AM. Prehospital use of the intubating laryngeal mask airway in patients with severe polytrauma: a case series. Case Report Med 2009; published online 25 June doi: / 2009/

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