Emergency front-of-neck access in cardiac arrest: A scoping review

Background Airway management is a core component of the treatment of cardiac arrest. Where a rescuer cannot establish a patent airway to provide oxygenation and ventilation using standard basic and advanced airway techniques, there may be a need to consider emergency front-of-neck airway access (eFONA, e.g., cricothyroidotomy), but there is limited evidence to inform this approach. Objectives This scoping review aims to identify the evidence for the use of eFONA techniques in patients with cardiac arrest. Methods In November 2023, we searched Medline, Embase, and Cochrane Central to identify studies on eFONA in adults. We included randomised controlled trials, non-randomised studies, and case series with at least five cases that described any use of eFONA. We extracted data, including study setting, population characteristics, intervention characteristics, and outcomes. Our analysis focused on four key areas: incidence of eFONA, eFONA success rates, clinical outcomes, and complications. Results The search identified 21,565 papers, of which 18,934 remained after de-duplication. After screening, we included 69 studies (53 reported incidence, 40 reported success rate, 38 reported clinical outcomes; 36 studies reported complications). We identified only one randomised controlled trial. Across studies, there was a total of 4,457 eFONA attempts, with a median of 31 attempts (interquartile range 16–56.5) per study. There was marked heterogeneity across studies that precluded any pooling of data. There were no studies that included only patients in cardiac arrest. Conclusion The available evidence for eFONA is extremely heterogeneous, with no studies specifically focusing on its use in adults with cardiac arrest.


Introduction
Airway management is a core component of cardiac arrest management. 1 During cardiac arrest, airway management by healthcare pro-viders typically begins with bag-mask ventilation, followed by a stepwise escalation to more definitive strategies such as supraglottic airway insertion or tracheal intubation. 2 Traditionally, tracheal intubation has been considered the gold standard for airway management in cardiac arrest, but out-of-hospital cardiac arrest randomised conhttps://doi.org/10.1016/j.resplu.trolled trials of tracheal intubation during cardiopulmonary resuscitation during out-of-hospital cardiac arrest have shown that it is not superior to bag mask ventilation or supraglottic airway use. 3,4There are ongoing studies on the role of tracheal intubation during CPR inhospital cardiac arrest setting. 5,6n some patients, standard basic and advanced airway techniques may not be effective leading to a cannot oxygenate scenario.The rescue strategy is the use of emergency front-of-neck access (eFONA) techniques, such as surgical cricothyroidotomy and needle cricothyroidotomy. 7A recent systematic review showed that prehospital use of eFONA had a very high success rate. 8.
To date, the International Liaison Committee on Resuscitation (ILCOR) has not incorporated eFONA in its treatment recommendations for airway management in adult cardiac arrest.On this basis, the ILCOR Advanced Life Support (ALS) Task Force prioritised the need for a scoping review to explore the role of eFONA in adult cardiac arrest.

Methods
The overarching objective of this scoping review was to explore the optimum airway management in cardiac arrest where initial strategies to achieve adequate ventilation and oxygenation have been unsuccessful, based on the following PICO (Population, Intervention, Comparator, Outcome) question: In adult patients in cardiac arrest in any setting where adequate ventilation cannot be rapidly achieved using basic/advanced airway management strategies, does using a front-of-neck airway access attempt compared with ongoing attempts at basic/advanced airway management strategies change any clinical outcome?
We anticipated limited evidence in this specific area, so planned a scoping review that explored eFONA use in critically ill patients in the in-hospital and out-of-hospital settings, focussing on four key areas: (1) Incidence of eFONA.
(3) Clinical outcomes in patients with an eFONA attempt.(4) Complications associated with eFONA attempts.This scoping review was undertaken in line with ILCOR's methodology for scoping reviews.This review paper is written in line with PRISMA checklist extension for scoping reviews. 9The ILCOR protocol template is available in the supplementary materials.

Eligibility criteria
We included randomised controlled trials, non-randomised studies (e.g., interrupted time series, controlled before-and-after studies, and cohort studies), and case series with at least five patients that described any use of eFONA in the pre-hospital or in-hospital setting.We excluded paediatric studies where all patients aged < 18 years old, simulation studies, studies that describe non-emergency surgical airways, animal studies, case series/reports with fewer than five patients, editorials, protocols, review papers, and letters.Grey literature was eligible for inclusion.In studies that included adults and children, we extracted only adult data where possible.

Information sources and search
We originally searched MEDLINE, Embase, and the Cochrane Library in June 2022, with search updates completed in January 2023 and November 2023.Search strategies were developed iteratively in collaboration with an information specialist (SJ).The searches combined keywords and index terms to describe the population, setting, and intervention of interest.The final search strategy is included in the supplementary materials.We did not limit the search by year of publication or language.We identified additional relevant studies, including grey literature, through liaison with subject experts and ILCOR Advanced Life Support Task Force members.We did not undertake specific searches for grey literature.

Selection of sources of evidence
Following the completion of searches, the list of citations was deduplicated using Endnote X9 and X9.3.3, and Rayyan software (https:// www.rayyan.ai/).Following deduplication, two reviewers (MA/AA) independently screened the titles and abstracts of the papers to exclude clearly irrelevant citations.The same two reviewers then independently reviewed the full text of potentially relevant studies.At each stage, reviewer conflicts were resolved through discussion or referral to a third reviewer.

Data charting, items and critical appraisal
After developing and piloting a bespoke online form for data extraction, two reviewers (MA/AA) independently extracted data items, including study setting, population characteristics, intervention characteristics, and outcomes.An overview of extracted data items is included in the supplementary materials.Conflicts between reviewers were resolved through discussion or referral to a third reviewer.We did not undertake a critical appraisal of the evidence, as the primary focus of this scoping review was to describe the volume, type, and key findings of the available evidence.

Synthesis of results
In line with the focus of this scoping review, we describe the findings in a narrative style for each of our four areas of focus.We present the results broken down for each key study setting (pre-hospital, inhospital, pre-hospital/in-hospital, and battlefield) and summarise the findings of studies that focus specifically on cardiac arrest.Quantitative analysis consisted of descriptive analyses, including the frequencies and ranges of the outcomes for the included studies.The qualitative analysis comprised descriptions of the overall results and outcomes.For both methods, Microsoft Excel supported data analysis.Where appropriate, we calculated a 95% confidence interval for relevant outcomes in each study.

Results
In total, our initial and updated searches identified 21,565 papers.Following the removal of duplicates, we screened 18,934 in the title/abstract stage, and then 445 full-text papers were retrieved for review (Fig. 1).In total, we included 69 studies.  Of t 69 included studies, there was one randomised controlled trial and 68 observational studies.The randomised controlled trial compared emergency cricothyrotomy and emergency percutaneous dilatational tracheotomy.50 Of the observational studies, 59 were retrospective, 7 were prospective, and 2 were case series. Fortyeight percent of the studies were conducted in the USA, and the rest were conducted in the UK, the Netherlands, Afghanistan, Iraq, Israel, Syria, Singapore, Germany, Denmark, Egypt, Korea, Japan, India, Australia and/or New Zealand.
Of the 69 studies, there were no studies that included only patients in cardiac arrest.In addition, 99% used surgical cricothyroidotomy as the eFONA technique, with or without using needle cricothyroidotomy or emergency tracheostomy in some cases.The included studies described a total of 4,457 eFONA attempts, with a median of 31 attempts (interquartile range 16-56.5)per study.Across studies, there was a range of reported rescuers, including emergency medicine physicians, anaesthetists, surgeons, paramedics, and nurses.Study duration ranged from several months to 20 years.Table 1 summarises the included studies.
Five studies (three pre-hospital and two in-hospital setting studies) reported health-related quality-of-life outcomes.None of the studies specified which scales or parameters were used to measure the results.Two studies reported that patients could speak normally after discharge. 40,46Poor patient health after eFONA was reported in one study, but another reported good recovery after the procedure. 10,Finally, one study reported that patients could care for themselves and were in an ambulatory status. 32

Discussion
Our scoping review, which included total of 4,457 eFONA attempts across 69 studies, provides important information on eFONA incidence, success rates, clinical outcomes, and complications.We identified no studies specific to adults in cardiac arrest.We found marked variation in the denominator used to calculate eFONA incidence with associated marked variation in incidence across studies.The reported success rates of eFONA were generally high and clinical outcomes appear to be influenced by the study setting.
Our scoping review builds on Morton and colleague's recently published systematic review and meta-analysis that focused on suc-

Return of spontaneous circulation
Pre-hospital 112 (Seven studies) 10,16,18,19,21,24,32 20% (range 0-64%) In-hospital 17 (One study) 41 41% Pre-hospital and inhospital 47 (One study) 63 0% Battlefield NA NA cess rates of eFONA in the pre-hospital setting. 8Morton et al.'s systematic review included 69 studies and found an overall eFONA success rate of 88%, with higher success rates reported with surgical techniques (92%) than needle techniques (52%).In contrast to that review, our review had a broader scope and we chose to exclude small case series due to their high risk of selection bias, such that we included fewer pre-hospital studies.Nevertheless, the reported overall success rate in our review (91%) was comparable to that reported by Morton et al (88%).The European Resuscitation Council and American Heart Association both recognise that there may be a need for eFONA during cardiac arrest. 1,79There are likely two main patient groups in which eFONA may need to be considered.First, a patient might have a hypoxic cardiac arrest in an established "cannot intubate, cannot oxygenate" scenario, where face-mask ventilation and placement of a supraglottic airway device has already been unsuccessful.In this case, UK Difficult Airway Society guidelines provide a clear framework for progression to eFONA as a 'Plan D' airway management strategy. 7he second patient group is patients in cardiac arrest in which providers are unable to successfully site a tracheal tube or supraglottic airway, due to patient anatomy, cardiac arrest aetiology, or environmental factors.In such cases, UK Difficult Airway Society guidelines recommend that providers attempt face-mask ventilation. 7owever, the adequacy of face-mask ventilation can be challenging to assess during cardiac arrest due to ongoing chest compressions and because standard strategies for determining adequate oxygenation, such as pulse oximetry, are unreliable in cardiac arrest. 1,80In such cases, healthcare providers will need to make a clinical judgement regarding the need for eFONA.Recent qualitative research with UK critical care paramedics described the stress associated with making a decision to perform eFONA. 81Our review findings provide reassurance that when appropriately skilled healthcare providers attempt eFONA, the success rate is usually high in all clinical settings, although index studies rarely provided information on provider training or exposure to eFONA.There is a need for further studies that report the incidence, success rate, and outcomes of patients in cardiac arrest that receive eFONA.However, undertaking highquality studies is likely to be extremely challenging due to the low incidence of eFONA in this population.This review has two important limitations.First, the index studies were extremely heterogeneous, in relation to study design, healthcare provider, and setting.Second, we chose not to undertake a risk or bias assessment as our overriding objective was to characterise the volume and type of existing evidence, rather than draw conclusions to inform clinical practice. 82Third, we chose to focus our scoping review on eFONA in adults.eFONA placement in children may be more challenging due to both patient factors and provider confidence and expertise, limiting the generalisability of our findings to children. 83A recent review highlighted that few data are available on eFONA in children. 83

Conclusion
Our scoping review found no studies specifically focusing on the use of eFONA during adult cardiac arrest.The available evidence suggests that the incidence of eFONA is generally low, but that, when attempted, the success rate is typically high.

Table 1 -
Characteristic of included studies.
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EMS: Emergency medical services; HEMS: Helicopter emergency medical services.

Table 4 -
Summary of outcomes in patients with eFONA that sustained a cardiac arrest.