a b s t r a c t

Purpose: Emergency pediatric airway management during restricted access to the head is challenging and may relate to an entrapped motor vehicle trauma. video laryngoscopy and supraglottic airways have separately been described to facilitate face-to-face airway management. We hypothesized that video laryngoscopy might be superior to direct laryngoscopy or supraglottic device use to establish ventilation during face-to-face airway management, studied in a simulated pediatric entrapped motor vehicle scenario.

Methods: Ethics approval was obtained from local REB. 45 experienced airway practitioners managed the airway of a Pediatric manikin representing a 6 year old (SimJunior). With a cervical collar applied and in the sitting po- sition, the manikin’s head was only accessible from the left anterolateral side. Following a standardized demon- stration, airway management using a Macintosh #2 blade (DL), a Storz C-MAC(R) D-Blade (VL) and a #2.5 LMA Supreme(TM) (SGD) was performed once each in a random order. Outcomes included success rate, time to ventila- tion (TTV), percentage of Glottic opening (POGO) for DL and VL and ease of use on a 10-point Likert scale (VAS). Data was analyzed using analysis of variance for TTV and VAS and t-test for POGO. Statistical significance was deemed at P < 0.05. Data are presented as median and interquartile range.

Results: Success rate was 95% for both DL and SGD and 93% for VL. TTV was significantly less with SGD compared to DL and VL. TTV was 31 s (28, 35) for DL, 46 s (31, 62) for VL and 20 s (17, 24) for SGD. POGO was significantly improved with VL (100%) compared to DL (80%). Participants rated SGD significantly easier to use than VL, but not easier than DL.

Discussion: All three techniques have high success rates. Time to establish ventilation with the SGD was signifi- cantly faster compared to DL and VL and participants rated SGD easiest to use. The utility of VL was limited due to significantly longer time to ventilation, despite significantly improved view compared to DL, similar to adult studies. Since time and success are clinically important, this study suggests that supraglottic devices should be considered for primary emergency pediatric airway management in situations with restricted access to the head.

(C) 2022

1. Introduction

Emergency pediatric airway management is challenging when ac- cess to the head is restricted [1]. The need for face-to-face airway man- agement may relate to an entrapped, unconscious motor vehicle trauma casualty. But it also applies to lost airways in cases in the emergency de- partment performed in the sitting or prone position [2]. Sitting or prone airway management in the pediatric patient in the emergency depart- ment is vanishingly rare, however it may be good practice to be

* Corresponding author at: Department of Pediatric Anesthesia, IWK Health Centre, 5850/5980 University Avenue, Halifax, Nova Scotia B3K 6R8, Canada.

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

prepared for the rare unexpected difficult airway. All three of direct lar- yngoscopy, video laryngoscopy and supraglottic airway devices have separately been described to facilitate face-to-face airway management in the adult population [3]. A current guideline for the management of the unanticipated difficult pediatric airway recommends the use of video laryngoscopy as a second choice should direct laryngoscopy fail [4]. Hyperangulated video laryngoscopy blades were invented for the expected difficult adult and pediatric airway. We hypothesized that hyperangulated blade video laryngoscopy might be superior to direct laryngoscopy or supraglottic airway use to establish ventilation during face-to-face airway management, studied in a simulated pediatric entrapped motor vehicle scenario. These are conditions that cannot be studied with live human subjects outside the context of observational case series.

https://doi.org/10.1016/j.ajem.2022.06.059

0735-6757/(C) 2022

1. Methods

Research ethics approval for this study was provided by the local re- search ethics board on October 25, 2019. Since there was no interven- tion on human participants, a trial registration was deferred.

To simulate a “MD” staffed prehospital team system rather than a Paramedic staffed, physicians were recruited as participants. With their informed consent, 45 experienced airway practitioners (staff anes- thesiologists and anesthesia residents with >300 intubations) managed the airway of a pediatric manikin representing a 6 year old (SimJunior

(TM), Laerdal, Puchheim, Germany) in January 2021. Following ATLS guidelines, with a cervical collar applied and in the sitting position, the manikin’s head was only accessible from the left anterolateral side, sim- ulating sitting on the driver side of a motor vehicle (or the passenger side of a car with British configuration) who can only be approached through the left side door. Using the device in the right hand, a stan- dardized demonstration was provided of face-to-face endotracheal intubation using a Macintosh #2 blade (DL) and a Storz C-MAC(R) D-Blade (VL, Karl Storz, Tuttlingen, Germany) as well as placement of a #2.5 LMA Supreme(TM) (SGA, Teleflex Medical Europe Inc., Athlone, Ireland). A malleable stylet was provided and every participant was able to bend the stylet in their preferred way, with the hockey stick version being the majority. The STORZ C-MAC D Blade is large for a 6 year old. Since most prehospital teams would only have an adult size hyperangulated blade on board due to space limitation and this study simulates a realistic prehospital scenario, the adult sized hyperangulated blade was choosen. All participants use hyperangulated blades in their routine practice. None of the participants had prior expe- rience of face to face intubations other than fiberoptic intubations. The Storz C-MAC(R) D-Blade was provided free of charge by Karl Storz, Tuttlingen, Germany. Participants then managed the airway once with each of the 3 devices, randomized using a computer generated alloca- tion to start with DL, VL or SGA. Outcomes included the success rate, time to ventilation (TTV), self reported percentage of glottic opening (POGO) visible for DL and VL and ease of use on a 10-point Likert scale (VAS). The primary outcome was the success rate, defined as manikin lung inflation detected by chest rise of Sim Junior, as well as ventilation in the Sim software occurring within 120 s after the tested device passed the lips. The 10-point Likert scale established 0 as “very easy” and 10 as “very difficult” for ease of use. Data was analyzed using analysis of var- iance for TTV and VAS and a t-test for POGO. Statistical significance was deemed at p < 0.05. Data are presented as median and interquartile range. No attempts were made to determine inter-rater reliability.

1. Results

Success rates, time to establish successful ventilation (TTV) and VAS ratings for ease of use for all three techniques appear in Table 1, together with POGO values for VL and DL. The success rate did not differ signifi- cantly between devices, but the TTV was significantly less with the SGA compared with each of VL and DL (Fig. 1). TTV was significantly

Fig. 1. Time to ventilation (TTV) (sec), Median, inter-quartile range and 5% and 95% per- centile, # (p < 0.001), * (p < 0.05).

less with DL compared with VL (Fig. 1). The POGO was significantly higher with VL compared to DL. Participants rated the SGA significantly easier to use than VL, but not DL. Rated ease of use did not differ signif- icantly between DL and VL.

1. Discussion

Although success rates did not differ, the utility of face-to-face VL was limited due to significantly longer time to establish ventilation, de- spite a significantly improved view with VL compared to DL. This find- ing is similar to adult studies. In one study simulating an entrapped adult patient, the shortest time to ventilation was achieved using the LMA Supreme (16.7 s) compared to DL (37.7 s) and indirect (video) lar- yngoscopy (41.2 s) [5]. The SGA was easiest to use and took the least amount of time to establish successful ventilation [5]. Another study similarly concluded that SGAs offer advantages in situations with re- stricted access to the head [6]. Perhaps reflecting some of the foregoing findings, in a recent large cohort study, endotracheal intubation was as- sociated with worse outcome in Pediatric out-of-hospital cardiac arrest, compared to SGA use [7].

In contrast a recent study in infants comparing first attempt success rates of standard blade video laryngoscopy (VL) versus direct laryngos- copy (DL) showed 93% for VL and 88% for DL, suggesting that video lar- yngoscopy should be considered for first attempt in children without Difficult airways [8]. The evidence for the use of hyperangulated blades in the pediatric population is unclear. One pediatric manikin study with difficult airway anatomy showed shorter time to ventilation using hyperangulated blades [9]. In contrast another study using a Pierre Robin sequence manikin showed the highest success rate using a nonangulated straight video laryngoscopy blade [10]. Hyperangulated

Table 1 Success rate, time to ventilation (TTV) and Visual analogue scale (VAS) ease of use for video laryngoscopy (VL), direct laryngoscopy (DL) and supraglottic device (SGA) use. Percentage of glottis opening (POGO) values are for VL and DL. Unless otherwise indicated, data are presented as Median (IQR). N/A = not applicable; NS = not statistically significant.

blades generally improve view of the glottis, but can make successful in- tubation difficult [11]. The result of a recent comparison of standard ver- sus non-standard video laryngoscopy blades in children in the Pediatric Difficult Inubation registry support the use of standard video laryngos- copy blades, because of significantly greater success rate [12].

Our study is biased by the typical limitations of manikin based re- search. Although the SimJunior manikin has typical anatomical airway features, it cannot simulate other difficult airway problems such as sal- ivation and blood obscuring the Laryngeal view especially using video laryngoscopy. Confirmation of appropriate placement of SGAs is difficult to achieve in manikins, due to the rigidity of the chest and detection of ventilation in the Sim software may not provide information of suffi- cient minute ventilation. However plastic on plastic in general provides less seal than plastic on mucosa and it can only be assumed, that SGA seal and ventilation would be improved in children.

Despite these limitations, basic psychomotor skills can be developed and studied during manikin training. An animal model would be pre- ferred but ethically debatable and studying airway management tech- niques initially in manikin is accepted [13].

The fact that only anesthesiologists participated in this study could be a potential bias. However emergency physicians, as well as advanced care paramedics are similar experienced airway practitioners. The non- blinded design of the study is another limitation. Unfortunately blinding the operator of a tested airway device is not possible. The study was not able to measure potential trauma to the upper lip, teeth and gum line. Despite encouraging participants to treat the manikin as a real patient, intubation attempts using direct or video laryngoscopy to achieve a good view may be more forceful in a manikin than in a human. Taking this and possible obscured views into consideration, the difference in time to ventilation or success rate between supraglottic airway device use and both direct and video laryngoscopy may be even greater in human Trauma victims.

1. Conclusion

Since both success rates and time taken to establish ventilation are clinically important parameters, our study suggests that SGAs should be considered for use in primary emergency pediatric airway manage- ment when access to the head is restricted.

Funding

The STORZ Pocket Monitor and DBlade was provided free of charge by KARL STORZ Endoscopy Canada Ltd.

This research did not receive any specific grant from funding agen- cies in the public, commercial, or not-for-profit sectors.

Presentation

This study was presented at the Annual Meeting of the Canadian Anaesthesia Society, 2021.

Author contribution

Conceptualization: AV, TD, JAL.

Data curation and formal analysis: AV, DV. Writing original draft: AV, DV.TD, JAL Writing review and editing: AV, TD, JAL.

CRediT authorship contribution statement Arnim Vlatten: Writing – review & editing, Writing – original draft,

Visualization, Validation, Supervision, Project administration, Method-

ology, Formal analysis, Data curation, Conceptualization. Tristan Dum- barton: Writing – review & editing, Writing – original draft, Methodology, Conceptualization. David Vlatten: Writing – review & editing, Writing – original draft, Visualization, Data curation. John Adam Law: Writing – review & editing, Writing – original draft, Visuali- zation, Conceptualization

Declaration of Competing Interest

none.

Acknowledgements

Assistance with this study: We would like to thank Dr. Christine Vlatten for her help with editing.

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