Health Technology Review

Airway Management in Out-of-Hospital Emergencies

What Is the Issue?

• Airway management is key to prehospital emergency care, impacting a patient’s survival and recovery. Endotracheal intubation has been considered the gold standard for airway management, yet its success in uncontrolled settings such as outside of the hospital can vary owing to the complexity of the procedure.

• Extraglottic airway devices, which include supraglottic and retroglottic airway devices, are an easier-to-insert alternative to endotracheal intubation; however, their impact on patient outcomes needs review.

What Did We Do?

• We compared the effectiveness of different types of extraglottic airway devices with endotracheal intubation, to inform decisions regarding the use of extraglottic airway devices in out-of-hospital emergencies. We focused on 2 types of supraglottic airway devices (i-gels and laryngeal mask airways) and 1 type of retroglottic airway device (King laryngeal tubes). We also sought to identify evidence-based guidelines regarding the use of extraglottic airway devices for this patient population.

• We searched key resources, including journal citation databases and conducted a focused internet search for relevant evidence published since 2019. Identified literature was reviewed, appraised, and summarized.

What Did We Find?

• Most identified studies were largely comprised of adults who had an out-of-hospital cardiac arrest (OHCA).

• I-gels were associated with higher rates of successful device insertion compared with King laryngeal tubes and laryngeal mask airways. I-gels also had higher rates of survival and return of spontaneous circulation (ROSC), and similar rates of adverse events compared with King laryngeal tubes. Significant differences for first-pass success, survival, and ROSC between i-gels and laryngeal mask airways were not reported. We did not identify any studies that met the inclusion criteria for this review that compared laryngeal mask airways with King laryngeal tubes.

• When compared with endotracheal intubation, i-gels and King laryngeal tubes were associated with higher rates of successful device insertion; however, King laryngeal tubes, laryngeal mask airways, and i-gels tended to have similar clinical outcomes or inconsistent findings. Exceptions included King laryngeal tubes having higher rates of ROSC, and laryngeal mask airways having lower survival to admission, though the difference on survival to discharge was not significant. A subgroup analysis by a randomized controlled trial (RCT) suggested i-gels may lead to better outcomes than endotracheal intubation for specific patients.

• In a nonrandomized study (NRS) that included patients with noncardiac arrest emergencies as well as pediatric patients, extraglottic airway devices were associated with higher rates of first-pass success than endotracheal intubation, with a larger effect seen in pediatric patients.

• One evidence-based guideline suggested supraglottic airway devices may be used for patients who had an OHCA. For pediatric patients who had an OHCA, experienced trauma, or experienced a medical emergency, the guideline recommended supraglottic airway devices compared with endotracheal intubation. The guideline noted missing sufficient evidence to make strong recommendations, yet reported that:

  • supraglottic airway devices were favoured compared with endotracheal intubation for pediatric patients owing to factors such as higher first-pass success rates, harms associated with failed endotracheal intubation attempts, and procedure rarity.

  • for adults who had an OHCA or medical emergency and determining between supraglottic airway devices and endotracheal intubation, the authors recommended considering documented success with endotracheal intubation. The authors recommended supraglottic airway devices for systems without documented success, and for systems with documented success, they suggested using either strategy.

What Does it Mean?

• Additional high-quality randomized studies are needed to fully understand the impact of extraglottic airway devices on patient-important outcomes for OHCA as well as other indications and for pediatric patients.

• Studies reported that i-gels were easier to insert and may also be associated with improved outcomes compared with King laryngeal tubes and similar outcomes compared with laryngeal mask airways. The use of the extraglottic airway devices was reported to result in similar patient outcomes as endotracheal intubation for patients who had out-of-hospital emergencies. Both i-gels and King laryngeal tubes were reported as easier to insert than endotracheal intubation.

• As most identified studies focused on adults who had an OHCA, it is unclear if these findings are generalizable to other patient groups, including patients with other indications and pediatric patients. Few studies reported on adverse events, which may result in an overestimation of the benefits of extraglottic airway devices. The identified evidence-based guideline includes different recommendations for pediatric and adult patients, which indicates that other factors may influence which advanced airway management strategy is optimal.

• Decisions regarding the use of extraglottic airway devices may depend on specific patient factors (e.g., adult versus pediatric, cause of emergency), local factors (e.g., if paramedics can maintain proficiency in endotracheal intubation), and each management strategy’s training needs.

Context and Policy Issues

What Is Airway Management?

Airway management are treatments and techniques to allow for oxygenation and ventilation, keeping the airway open.¹ Airway management is a vital aspect of prehospital emergency care, and is key to a patient’s survival and their potential for recovery.² They are used for a variety of critical conditions that require airway management, including cardiac arrest, trauma, medication or drug toxicity, pneumonia, and pulmonary edema.³ A variety of airway management techniques are available, including endotracheal intubation and extraglottic airway devices.²

What are Extraglottic Airway Devices?

Extraglottic airway devices are invasive devices that are inserted through the oropharynx but do not enter the larynx or trachea.³ They are important tools for airway management used to establish an airway for oxygenation and ventilation as well as to administer anesthetic gases without entering the trachea.⁴ They are used in a variety of health care settings including prehospital.

There are 2 categories of extraglottic airway devices:

• Supraglottic airway devices sit in the hypopharynx facing the glottis, with the tip in the esophageal inlet.⁵ Types of supraglottic airway devices include:

  • laryngeal mask airways: a device with an airway tube and a mask-like cuff⁵

  • i-gels: a device with a noninflatable gel cuff, provides a seal and reduces concerns about cuff pressures. It also has a gastric vent, integral bite block, and flange to prevent epiglottic folding.⁵

• Retroglottic devices are laryngeal tubes that are seated behind the glottic opening, or terminate in the upper esophagus.^3,4 One example of a retroglottic device is the King laryngeal tube, which has a pharyngeal cuff and esophageal cuff, with a port between the cuffs at the laryngeal inlet to allow for gas exchange.

Why Is It Important To Do This Review?

Endotracheal intubation is considered the gold standard for airway management;² however, it is a complex procedure, and its success rate in out-of-hospital emergencies varies.^2,6 Extraglottic devices, particularly supraglottic devices, have been increasingly used in out-of-hospital emergency settings owing to their simpler insertion technique and thus can be taught more successfully compared with endotracheal intubation.^6,7 Determining which device or procedure is most clinically effective in out-of-hospital and prehospital settings may help to improve patient outcomes.

Objective

The purpose of this report is to summarize and critically appraise the evidence regarding the clinical effectiveness between different types of extraglottic airway devices for out-of-hospital emergencies, as well as extraglottic devices compared with endotracheal intubation. This review focused on 2 types of supraglottic airway devices (i-gels and laryngeal mask airways) and 1 type of retroglottic airway device (King laryngeal tubes). This review also aimed to summarize and critically appraise evidence-based guidelines regarding extraglottic airway devices for out-of-hospital emergencies.

Research Questions

1. What is the comparative clinical effectiveness of different types of extraglottic airway devices in out-of-hospital emergencies?

2. What is the clinical effectiveness of extraglottic airway devices versus endotracheal intubation?

3. What are the evidence-based guidelines regarding extraglottic airway devices in out-of-hospital emergencies?

Methods

An information specialist conducted a customized literature search, balancing comprehensiveness with relevancy, of multiple sources and grey literature on August 8, 2024.

Two reviewers screened citations and selected studies based on the inclusion criteria presented in Table 1. Two reviewers critically appraised and included publications using established critical appraisal tools.

Appendix 1 presents a detailed description of methods.

Table 1: Selection Criteria

LMA = laryngeal mask airway; NA = not applicable; vs. = versus.

Summary of Evidence

Quantity of Research Available

A total of 442 citations were identified. Following screening of titles and abstracts, 381 citations were excluded and 61 potentially relevant reports from the electronic search were retrieved for full-text review. No potentially relevant publications were retrieved from the grey literature search for full-text review. Of these potentially relevant articles, 46 publications were excluded for various reasons, and 15 publications met the inclusion criteria and were included in this report.

Publications included 3 systematic reviews (SRs),^2,8,9 1 RCT,¹⁰ 10 NRSs,^11-20 and 1 evidence-based guideline.²¹ This review did not identify any health technology assessments that met the inclusion criteria. Appendix 2 presents the PRISMA²² flow chart of the study selection.

Additional references of potential interest are provided in Appendix 8.

Summary of Study Characteristics

This review included 15 publications, including 3 SRs,^2,8,9 1 RCT,¹⁰ 10 NRSs,^11-20 and 1 evidence-based guideline.²¹ The 3 included SRs^2,8,9 conducted meta-analyses; 1 SR² did not conduct a meta-analysis for a comparison of interest for this report, subsequently that meta-analysis result (bag valve mask versus endotracheal intubation) was not included in this review. Two SRs^2,9 had broader inclusion criteria than this report, including other types of airway interventions such as bag valve masks. This review reported on the characteristics and results from the subset of relevant studies.

Summaries of study characteristics are organized by research question and comparison. Additional details regarding the characteristics of the included publications are provided in Appendix 3.

Question 1: Clinical Effectiveness Between Extraglottic Airway Devices

This review included 1 SR² and 4 observational studies^11-14 that compared the clinical effectiveness of i-gel with alternative extraglottic airway devices (laryngeal mask airway and King laryngeal tube).

I-gel Compared With Laryngeal Mask Airway

One SR² compared i-gel with laryngeal mask airways in patients who had an OHCA requiring airway management. Authors from the US conducted the SR without specifying countries where the relevant primary studies were performed. The SR did not report the types of health care providers inserting the devices.²

I-gel Compared With King Laryngeal Tube

Three retrospective^12-14 and 1 prospective¹¹ NRS compared the clinical effectiveness of i-gel and King laryngeal tubes in patients who had an OHCA with 2 studies,^13,14 specifically on nontraumatic OHCA. These studies were conducted in Canada,¹² US,^13,14 and Norway.¹² Reported patient mean or median age ranged from 63 to 71 years, with 25% to 36.9% being female.^11-14 Airway device insertion was attempted by the emergency medical system personnel^11,13,14 or paramedics.¹²

Clinical outcomes assessed across studies included:

• survival (e.g., survival to hospital admission and hospital discharge)^2,13,14

• survival with a favourable neurologic outcome (defined as a Cerebral Performance Category score of 1 or 2 at discharge)¹⁴

• ROSC^2,13,14

• first-pass success^2,11-13

• other success rates of airway device placement^2,11,12

• prehospital rearrest^13,14

• end-tidal carbon dioxide (ETCO2) levels¹³

• difficulty of insertion¹¹

• complications.¹¹

Question 2: Clinical Effectiveness of Extraglottic Airway Devices Compared With Endotracheal Intubation

This review included 2 SRs with meta-analyses^8,9 and 7 primary studies^10,15-20 comparing the clinical effectiveness of supraglottic airway devices with endotracheal intubation.

I-gel Compared With Endotracheal Intubation

Six primary studies compared the effectiveness of i-gel with endotracheal intubation, including 1 open, parallel, multicentre, cluster RCT,¹⁰ 2 prospective observational studies,^19,20 and 3 retrospective studies.^15,17,18 Four studies focused on patients who had an OHCA,^10,15,17,19 while 2 other studies^18,20 included more than 85% of patients experiencing OHCA. The mean or median age of patients ranged from 60.1 years to 73 years, with 54% to 71.3% being male.^10,15,17-20 Airway device insertion was attempted by paramedics^10,18,20 or personnel from the emergency medical system or ambulance team.^15,17,19

Laryngeal Mask Airway Compared With Endotracheal Intubation

One SR with meta-analysis compared laryngeal mask airways with tracheal intubation in patients who had an OHCA. The relevant 7 observational studies and 2 RCTs included in the SR were conducted in Japan, England, Taiwan, South Korea, and the US. The mean or median age of patients ranged from 60.8 years to 75.8 years, with 55% to 76% being male. The SR did not specify the types of health care providers inserting the devices.⁹

Multiple Types of Supraglottic Airway Devices Compared With Endotracheal Intubation

One SR with meta-analysis⁸ and 1 retrospective observational study¹⁶ compared the clinical effectiveness of multiple supraglottic airway devices (i.e., i-gel, laryngeal mask airway, and King laryngeal tube) as a group to tracheal intubation. All 4 RCTs in the SR were relevant to this report, including 1 study on laryngeal mask airway supreme, 1 on King laryngeal tube, and 2 on i-gel. They were conducted in adults aged 64 to 75 years who had an OHCA in the Netherlands, UK, US, and Taiwan. The SR did not specify the type of health care provider(s) who inserted the devices.⁸ The retrospective study, conducted in the US, included patients with at least 1 advanced airway management attempt by personnel from the emergency medical system. The median age was 65.2 years for adults and 2.3 years for pediatric patients, and 41.4% of adults and 38.9% of pediatric patients were female.⁹

Clinical outcomes assessed across studies for research question 2 included:

• survival outcomes: survival to admission⁹ and discharge,^9,10,17 survival to longest follow-up,⁸ mortality at 28 days¹⁸

• ROSC^8-10,17-19

• first-pass success^10,16,18,20

• other success rates and placement attempts^10,18,20

• ventilator-free days¹⁰

• hospital length of stay¹⁰

• functional outcomes: good functional recovery (defined as a modified Rankin Scale score of 0 to 3 or as defined by study authors),^8,10 favourable neurologic outcome (defined as Cerebral Performance Category score of 1 to 2),¹⁷ poor neurologic outcome (defined as a Cerebral Performance Category score of 3 to 5)¹⁵

• quality of life (assessed by the EQ-5D-5L scale)¹⁰

• time-related outcomes: time to advanced airway placement,⁸ time to successful first attempt,¹⁸ and time to successful airway placement¹⁸

• adverse events.^10,17,20

Question 3: Guidelines Regarding the Use of Extraglottic Airway Devices

This report included 1 evidence-based guideline published in 2024 by the US Agency for Health Care Research and Quality (AHRQ) for emergency medical services clinicians on prehospital airway management.²¹ They conducted an SR of RCTs and observational studies and rated evidence by quality based on the AHRQ method guide; quality was rated on a scale that ranged from insufficient to high.^23,24 Using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method, an expert panel assessed the strengths of recommendations and reached consensus on final statements.²¹

Summary of Critical Appraisal

Summaries of critical appraisal are presented, organized by study design. Additional details regarding the strengths and limitations of the included publications are provided in Appendix 4.

Systematic Reviews

All 3 SRs^2,8,9 included clear presentation of research questions, study eligibility criteria, as well as funding and conflicts of interest for authors. All SRs^2,8,9 also assessed risk of bias in included studies, with 2 SRs^2,8 also evaluating the strength or certainty of evidence.

Additional strengths included protocol registration by 2 SRs,^2,8 which can improve transparency and may help to reduce selective reporting. One⁹ of the 2 SRs^2,8 reported that while funnel plots to assess publication bias were planned, they were not conducted as fewer than 10 trials were included in the analysis. It is unclear whether Yang et al. developed a protocol in advance.⁹ Two SRs^2,8 performed database and grey literature searches; 1 study⁸ reported the grey literature search strategy. Yang et al. searched databases but did not report a grey literature search; it is unclear whether the SR identified all relevant studies.⁹ Duplicate and independent screening of study titles, abstracts, full texts, and data extraction were performed in 2 SRs.^8,9 The other SR² screened full texts in duplicate. It did not consistently screen abstracts by 2 reviewers, and the data extraction method was unclear, increasing the risk of missing relevant studies or errors in data extraction. The 2 SRs^8,9 described included studies in detail, while the other SR² provided limited information.

The 3 SRs^2,8,9 had common limitations including the lack of justification for choice of included study designs and sources of funding for included studies. None of the SRs explicitly accounted for risk of bias in the interpretation of findings, which can impact the interpretation of results. Forestell et al. reported no evidence of effect modification on outcomes of interest in subgroup analyses by risk of bias level,⁸ and Yang et al. acknowledged potential bias in some outcomes.⁹ Other limitations included the absence of a list of excluded studies^8,9 and the missing results of discussion on heterogeneity in review.^2,9 Two SRs^8,9 conducted meta-analyses; 1 study⁹ explained choice of the analysis model and assessed publication bias.

Randomized Controlled Trial

The RCT¹⁰ clearly reported the study objective, the intervention, participant characteristics, main outcomes including P values, main findings, and funding sources. Paramedics were randomized as clusters to use the intervention or control to treat patients. The intervention and control groups were followed for the same period. Statistical tests were used appropriately, and the main outcome measures were accurate and reliable. The primary outcomes were powered to detect a clinically important difference. The study reported severe adverse events; however, it is unclear if all important adverse events were reported.¹⁰

Several factors affected the internal validity of this RCT. Allocation concealment was not conducted during patient enrolment. To reduce selection bias, all eligible patients were automatically enrolled. Blinding was performed in ambulance control room personnel, clinical staff caring for patients beyond the emergency department, researchers assessing the outcomes, and patients (who were unconscious during the intervention) to reduce performance and detection bias. The lack of blinding for paramedics and emergency department staff owing to the nature of the interventional procedure may lead to performance bias. Other limitations included crossover between groups (4 patients in the intervention group and 3 in the control group) and about one-half of the eligible patients not consenting to follow-up, thus reducing the power of the follow-up analyses. Sensitivity analyses (intention-to-treat analysis and as treated) were performed to estimate these effects.¹⁰

The study was conducted across 4 ambulance services, which were representative of the treatment most of the patients received. Patients were likely representative of the population from which they were recruited. Researchers acknowledged that participating paramedics were volunteers whose airway skills may not represent paramedics who did not participate in the study. Study findings may not be generalized to patients treated by paramedics with different skill levels. Characteristics of patients lost to follow-up were not reported. The large number of missing data in follow-up reduced the generalizability of findings to patients recovering after OHCA.¹⁰

Nonrandomized Studies

All 10 NRSs^11-20 clearly described objectives, inclusion criteria, interventions, patient characteristics, main outcomes with random variability estimates, and findings. Eight studies^11,12,15-20 reported actual P values for main outcomes; 4 studies^11,17,18,20 reported some adverse events.

Methodological limitations in all included NRSs,^11-20 such as the lack of randomization and blinding owing to the observational design, increased the risks of selection, performance, and detection bias. Some outcomes such as neurologic outcomes,^14,17 successful airway management,^12,16,20 and ease of insertion¹¹ were subjectively evaluated and may be influenced by the lack of blinding. One study noted that successful airway management may be overreported.¹⁶ Seven^12-18 retrospective studies relied on data not specifically collected for them, leading to missing data and low data quality owing to unstandardized collection. All studies followed patients in the intervention and control groups for the same amount of time and used appropriate statistical tests to analyze main outcomes, which were measured using accurate and valid methods.

Regarding internal validity impacted by confounders, 6 studies^{13,15-17,19,20} recruited patients from the same population during the same period, ensuring consistency in health care received between groups. One study¹¹ recruited different populations, and 3 other studies^12,14,18 recruited patients from different periods of time. Eight studies^11,12,15-19 did not identify potential confounders, including 2 studies^19,20 not describing patient baseline similarities, making it difficult to interpret study findings. Two studies^13,14 did not describe characteristics of patients lost to follow-up. While 6 studies^{12-14,16,17,20} considered confounders in analysis, 4^12,16,17,20 only adjusted for some. It is unclear whether findings from the other 4 studies^11,15,18,19 not assessing confounders may be affected by unmeasured factors (e.g., patient age).

For external validity, all^11-14,16-20 but 1 study¹⁵ included patients representative of the entire eligible population and treated in settings representative of the treatment received by most patients. One study¹³ with substantial missing data indicated that the findings may not be generalizable to patients not being followed up.

Four studies^13,15,18,20 indicated that they were likely underpowered to detect a significant effect for certain outcomes. Five studies^{11,12,14,17,19} did not report whether sample size calculations were performed. It is uncertain whether the nonsignificant differences in some outcomes could be owing to insufficient statistical power.

Evidence-Based Guideline

The AHRQ guideline²¹ clearly described its scope and purpose, including objectives, health questions, and the targeted population. Relevant professional groups and target users were involved in guideline development, though patient views and preferences were not included. It reported a systematic search for evidence, study selection criteria, evidence strengths and limitations, methods for formulating recommendations, and the link between recommendations and supporting evidence. It also considered health benefits, side effects, and risks in formulating the recommendations. The lack of external review and an updating procedure may reduce the rigour of guideline development.²¹

The guideline provided clear recommendations and options for management of the condition. It described facilitators and barriers to its application, with advice on implementation and resources required. The guideline did not report the monitoring or auditing criteria, which may limit its applicability.²¹

Regarding editorial independence, the guideline stated that views of the funding body had no influence on its content. It also recorded and addressed competing interests of guideline development members.²¹

Summary of Findings

Appendix 5 presents the main study findings.

Question 1: Clinical Effectiveness Between Extraglottic Airway Devices

I-gel Compared With King Laryngeal Tube

Overall, patients who had an OHCA and received i-gels tended to have better outcomes compared with King laryngeal tubes. Outcomes where i-gels were associated with statistically significantly better outcomes included:

• higher rates of successful device insertion (e.g., higher proportion of patients who had first-pass success, fewer attempts required for successful insertion, fewer patients with failed insertion; 3 NRSs^11-13). One NRS¹¹ reported the proportion of patients who had a successful insertion after 3 attempts from the same personnel or attempts from 2 or more personnel did not differ statistically significantly between groups

• higher survival to discharge at home (2 NRSs^13,14), hospital admission, hospital discharge, and discharge with good neurologic outcomes (1 NRS;¹⁴ tools used to measure neurologic outcomes are presented as footnotes in Appendix 5)

• higher rates of ROSC (2 NRSs^13,14)

• fewer patients with low levels of ETCO2 (used as an indirect measure of ventilation success; low ETCO2 levels indicate ventilation failure) (1 NRS¹³)

• reported ease of device insertion: i-gels were more likely to be reported as easy to insert, while King laryngeal tubes were more likely to be reported as medium-to-very difficult when inserting (1 NRS¹¹).

Results were mixed for rearrest: 1 NRS¹³ reported statistically significantly lower odds of rearrest for patients treated with i-gels compared with King laryngeal tubes, while another NRS¹⁴ did not find a statistically significant difference.

One NRS¹¹ reported that the number of reported complications generally did not differ statistically significantly between groups, excluding anatomic conditions, problematic insertion, and insertion taking longer than 30 seconds, all of which were higher in the King laryngeal tube group.

I-gels Compared With Laryngeal Mask Airways

The SR² overall reported no significant differences for patients who had an OHCA and received i-gels compared with laryngeal mask airways on first-pass success, survival, and ROSC. They identified 1 RCT that reported i-gels were associated with higher proportions of overall successful insertion (90% versus 57%).

King Laryngeal Tubes Compared With Laryngeal Mask Airways

This review did not identify any studies that compared King laryngeal tubes with laryngeal mask airways that met the inclusion criteria for this report; therefore, no summary can be provided.

Question 2: Clinical Effectiveness of Extraglottic Airway Devices Compared With Endotracheal Intubation

I-gels Compared With Endotracheal Intubation

Most included studies were restricted to patients who experienced OHCA; 2 studies^18,20 included patients with noncardiac emergencies, though for both studies, more than 85% of patients had cardiac arrest. Across these studies, i-gels were associated with better outcomes than endotracheal intubation on a few outcomes:

• first-pass success (1 RCT¹⁰ and 1 NRS¹⁸); however, 1 NRS²⁰ also reported similar rates between groups

• overall success at device insertion (1 RCT¹⁰ and 2 NRSs^18,20)

• shorter time to device insertion (1 RCT from 1 SR⁸ and 1 NRS¹⁸) and shorter time to first attempt (1 NRS¹⁸).

Mixed results were found for:

• ROSC: 2 RCTs^8,10 (including 1 from the SR⁸) reported that patients in the i-gel group were more likely to experience ROSC, while 1 RCT (from the SR⁸) and 3 NRSs^17-19 reported no statistically significant difference between groups.

• favourable neurologic outcome: 1 RCT¹⁰ and 2 NRSs^15,17 reported no statistically significant difference (tools used to measure neurologic outcomes are presented as footnotes in Appendix 5). The RCT¹⁰ reported that more patients in the i-gel group had better functional outcomes from 1 sensitivity analysis (excluded patients who did not receive i-gel or endotracheal intubation), and 2 subgroup analyses:

  • restricted to non-Utstein patients (Utstein patients are those whose OHCA was likely owing to a cardiac cause, is witnessed, and has an initial rhythm amenable to defibrillation)

  • restricted to patients who had ventilation success within first 2 attempts.

No statistically significant difference was found for:

• survival (2 RCTs^8,10 including 1 from the SR,⁸ and 2 NRSs^17,18)

• length of stay in the hospital (1 RCT¹⁰) or intensive care unit (1 RCT¹⁰ and 1 NRS¹⁸) or number of days that were ventilator-free (1 NRS¹⁸)

• quality of life at 30 days or hospital discharge, 3 months, or 6 months (1 RCT;¹⁰ tools used to measure quality of life are presented as footnotes in Appendix 5)

• adverse events (1 RCT¹⁰ and 2 NRSs^17,18).

Laryngeal Mask Airways Compared With Endotracheal Intubation

One SR with meta-analysis⁹ reported that based on 5 studies of patients who had an OHCA, survival to admission was statistically significantly higher for patients who received endotracheal intubation. Survival to discharge was also slightly higher in the endotracheal intubation group but this was not statistically significant, based on a pooled analysis of 8 studies.

Findings for ROSC were mixed: 1 RCT (identified by 1 SR⁸) reported no statistically significant difference on sustained ROSC, though it was slightly higher for the patients who received laryngeal mask airways. However, 1 SR with meta-analysis⁹ reported that based on their pooled analysis of 7 studies, endotracheal intubation was associated with statistically significantly higher ROSC rates.

King Laryngeal Tube Compared With Endotracheal Intubation

One RCT identified by 1 SR⁸ reported that patients who had an OHCA who received King laryngeal tubes tended to have higher rates of ROSC and shorter time to device insertion. Survival was also slightly higher, though this was not statistically significant, for patients in the King laryngeal tube group.

Multiple Types of Supraglottic Airway Devices Compared With Endotracheal Intubation

Publications that grouped together several types of supraglottic airway devices included 1 NRS¹⁶ and 1 SR with meta-analysis⁸ that pooled multiple studies. The individual studies from the meta-analysis⁸ have been reported individually by specific type of device previously, and their pooled results are not summarized here. Details about the pooled results from this meta-analysis are available in Appendix 5 (Table 19, Table 20, and Table 21).

The NRS¹⁶ included adult and pediatric patients who had an OHCA as well as other indications and reported better outcomes for patients who received supraglottic airway devices compared with endotracheal intubation. They also reported that patients who received supraglottic airway devices tended to have higher rates of first-pass success compared with patients who received endotracheal intubation. This difference was larger for pediatric patients compared with adult patients.

Question 3: Guidelines Regarding the Use of Extraglottic Airway Devices

The guideline by AHRQ²¹ provided several recommendations regarding the use of supraglottic airway devices for patients experiencing out-of-hospital emergencies. All recommendations were conditional, with the certainty of evidence reported as very low or low to moderate owing to limited data, particularly on patient outcomes. These recommendations are summarized in Table 2.

Table 2: Summary of Recommendations Regarding the Use of Extraglottic Airway Devices

BVM = bag valve mask; ETI = endotracheal intubation; OHCA = out-of-hospital cardiac arrest; SGA = supraglottic airway devices.

Notes:

High ETI proficiency appeared to be defined by the guideline as having documentation of high intubation first-pass success rates. The guideline authors noted that the literature did not have an established definition for high first-pass success rate (i.e., what percentage would be considered high).

SGA was favoured for pediatric patients owing to factors such as higher first-pass success rates, harms associated with failed ETI attempts, and procedure rarity. Additional details regarding factors considered for each recommendation are available in Appendix 5.

For patients who had an OHCA (adult or pediatric) or adults who have experienced trauma, the guideline recommended supraglottic airway devices or bag valve masks, based on little evidence to indicate if one was superior.²¹ The guideline also noted that bag valve mask ventilation often required more clinicians, indicating resource availability might influence treatment choice. The guideline did not provide recommendations regarding the use of bag valve mask or supraglottic airway devices for pediatric patients who have experienced trauma or patients of any age with medical emergencies owing to lack of evidence.

For adults who had an OHCA or medical emergency, the guideline suggested that choosing between supraglottic airway devices and endotracheal intubation should be influenced by documented success with endotracheal intubation:²¹

• for systems with demonstrated high endotracheal intubation proficiency, use either supraglottic airway devices or endotracheal intubation

• for systems without demonstrated high endotracheal intubation proficiency, use supraglottic airway devices compared with endotracheal intubation.

For pediatric patients who had an OHCA, experienced trauma, or experienced a medical emergency, they suggested using supraglottic airway devices compared with endotracheal intubation.²¹

A summary of recommendations from nonevidence-based guidelines is available in Appendix 7.

Limitations

Risk of Bias of Included Studies in Systematic Reviews

Of the included studies of interest in the 3 SRs, as assessed by the review authors, 8 studies from 3 SRs were at low risk of bias; however, the other 7 studies were either at high risk of bias or had concerns about the relevant selection, performance, and detection bias as well as comparability.^2,8,9

External Validity

Most included studies were restricted to patients who had experienced an OHCA, including all studies that compared extraglottic airway devices. Some studies also had other restriction criteria that may limit their generalizability. For example, Smida et al.¹⁴ was restricted to patients with successful advanced airway management, and Edwards et al.¹⁵ only included patients who were transferred to a specialized heart attack centre. It is unclear if these findings are generalizable to a wider population, as well as to patients who required advanced airway management for a different reason. It is also unclear if these findings are generalizable to patients in Canada, as only 1 NRS¹² comparing i-gel with King laryngeal tube was conducted in Canada.

Evidence Gaps

Most studies were restricted to adults only; while a few studies did not state they were restricted to adults, most tended to have a higher mean or median age, suggesting their patients were likely primarily adults or older adults. Only 1 study¹⁶ provided a subgroup analysis of pediatric patients. This study also grouped together multiple types of extraglottic devices compared with endotracheal intubation, and did not report results by specific type of device (e.g., i-gels compared with endotracheal intubation). This review did not identify any studies that compared different supraglottic airway devices in a pediatric population.

This review identified 1 evidence-based guideline²¹ that provided recommendations regarding the general use of supraglottic airway devices, including situations where they are preferred compared with endotracheal intubation. This guideline did not provide recommendations regarding the use of specific types of extraglottic airway devices. They also were unable to provide recommendations for specific populations owing to a lack of evidence.

This review identified few studies comparing i-gels with laryngeal mask airways (1 SR with 2 RCTs)² and King laryngeal tubes with endotracheal intubation (1 SR with 1 RCT).⁸ Few studies reported on adverse events, which were limited to studies that compared i-gels with King laryngeal tubes,¹¹ and studies that compared i-gels with endotracheal intubation.^10,17,18,20 Without a clear understanding of the type and frequency of adverse events an intervention is associated with, decision-makers may overestimate the benefits and underestimate the risks of an intervention to patients. This review did not identify any publications that compared laryngeal mask airways with King laryngeal tubes.

Complexity of Assessing Airway Management in Out-of-Hospital Emergencies

It is a challenge to assess the effectiveness of different airway management devices outside of controlled settings, as outcomes are also affected by factors such as provider experience and training and cause of respiratory distress that can be hard to control for.⁶ Well-conducted RCTs can help to address the issue of confounders yet are also difficult to conduct well. Most studies included in this report were NRSs, and their findings may have been influenced by confounding variables.

Conclusions and Implications for Decision- or Policy-Making

Summary of Evidence

This rapid review evaluated the literature regarding the clinical effectiveness of different types of extraglottic airway devices, as well as extraglottic airway devices compared with endotracheal intubation, for patients experiencing out-of-hospital emergencies, and evidence-based guidelines regarding the use of extraglottic airway devices. This review identified:

• 1 SR² and 4 NRSs^11-14 that compared different types of extraglottic devices

• 2 SRs,^8,9 1 RCT,¹⁰ and 6 NRSs^15-20 that compared an extraglottic airway device with endotracheal intubation

• 1 evidence-based guideline²¹ regarding the use of extraglottic airway devices for this patient population.

All the studies that compared extraglottic airway devices were focused on patients who experienced OHCA. Studies that compared i-gels to King laryngeal tubes tended to report i-gels were associated with higher rates of successful device insertion^11-13 and survival,^13,14 including survival with good neurologic outcomes.¹⁴ Only 1 NRS¹¹ reported on adverse events for this comparison and found similar rates of complications between groups, though a few complications occurred more frequently in the King laryngeal tube group. Two NRSs^13,14 reported on rearrest and had mixed findings. One SR² reported 2 RCTs that compared i-gels with laryngeal mask airways: they reported no significant differences between groups, except successful insertion, which was higher in the i-gel group.

Most studies that compared extraglottic airway devices with endotracheal intubation were restricted to patients who experienced OHCA or primarily included this patient group. I-gels were associated with higher or similar rates of successful insertion, when compared with endotracheal intubation;^15,18,20 no statistically significant difference was found on survival,^8,10,17,18 hospital length of stay,^10,18 quality of life,¹⁰ or adverse events.^10,17,18 Results were mixed for ROSC^8,10,17-19 and neurologic outcomes.^10,15,17 The RCT¹⁰ noted i-gels were more likely to be associated with favourable neurologic outcomes if the analysis was restricted to certain subgroups. This may indicate that i-gels are more clinically effective than endotracheal intubation for specific patient populations, but further studies are needed to assess this.

One SR with meta-analysis⁹ reported that compared with endotracheal intubation, laryngeal mask airways were associated with improved survival to admission, though it may not be associated with a statistically significantly improved survival to discharge. Results for ROSC were mixed.^8,9 One RCT was identified by 1 SR⁸ and found higher rates of ROSC and shorter time to device insertion for patients who received King laryngeal tubes compared with patients who received endotracheal intubation; survival was also higher for this group, but it was not statistically significant.

One NRS¹⁶ included patients who required airway management for cardiac arrest as well as patients who had not had a cardiac arrest and included pediatric and adult patients. Their analyses indicated that supraglottic airway devices in general (which included i-gels, King laryngeal tubes, and laryngeal mask airways) were associated with higher rates of first-pass success than endotracheal intubation, with a larger benefit seen in pediatric patients.

In summary, the identified publications suggest that using i-gels may lead to improved outcomes when compared with King laryngeal tubes. I-gels were preferred than laryngeal mask airways and endotracheal intubation on successful device insertion; however, other outcomes were either not statistically significantly different or had mixed findings. Limited evidence suggests that laryngeal mask airways and King laryngeal tubes may lead to improved or similar outcomes when compared with endotracheal intubation. The identified studies were primarily in adults who had an OHCA, and their generalizability to other populations is unclear.

The identified guideline²¹ recommended using a supraglottic airway device for airway management in adults or pediatric patients who had an OHCA, and for adults who have experienced trauma. They suggested supraglottic airway devices or endotracheal intubation can be used for adults who have experienced trauma, but recommended supraglottic airway devices compared with endotracheal intubation if endotracheal intubation proficiency has not been demonstrated by adults who had an OHCA or medical emergency. They also recommended supraglottic airway devices compared with endotracheal intubation for pediatric patients who had an OHCA, have experienced trauma, or have had medical emergencies.²¹ The guideline also noted that when studies on patient-oriented outcomes were unavailable, they considered studies on outcomes like procedure success or first-pass success, owing to the harms associated with failed device insertion.²¹

Considerations for Future Research

Additional high-quality studies with large sample sizes that assess the effectiveness of extraglottic airway devices for patients with other types of emergencies (i.e., other than cardiac arrest), as well as for pediatric patients, may help to develop our understanding of what airway management strategies are appropriate for specific patient populations. Studies that assess patient-important outcomes like survival, quality of life, and adverse events would also be beneficial.

Considerations for Decision- or Policy-Making

In addition to considering clinical effectiveness, health care decision-makers may consider other factors related to the use of different airway management strategies. For example, endotracheal intubation is a complex procedure that requires extensive training and experience, as well as more time for application.¹⁹ Supraglottic airway devices are comparatively easier to use, require less training, and are safe for patients. In settings where it is difficult for emergency medical services to obtain the experience required to maintain their skills in endotracheal intubation in this population (e.g., rural areas where a paramedic may not need to provide advanced airway management for more than a year),¹² supraglottic airway devices may be safer.²¹ However, there may be some patients who cannot experience effective ventilation with a supraglottic airway device, and require endotracheal intubation for ventilation.¹⁰ Considering specific patient factors when deciding which strategy to use may help to optimize patient outcomes. Decision-makers may also want to consider the barriers and facilitators for accessing training for different management strategies and devices.

References

1.Huitink JM, Bretschneider JH. Airway Management Academy: A global initiative to increase patient safety during airway management by medical education. Trends in Anaesthesia and Critical Care. 2015;5(1):42-47.

2.Carney N, Cheney T, Totten A, et al. Prehospital Airway Management: A Systematic Review. Comparative Effectiveness Review No. 243. (Prepared by the Pacific Northwest Evidence-based Practice Center under Contract No. 290-2015-00009-I.). Rockville (MD): Agency for Healthcare Research and Quality; 2021: https://effectivehealthcare.ahrq.gov/products/prehospital-airway-management/research. Accessed 2024 Aug 14.

3.Braude D, Steuerwald M, Wray T, Galgon R. Managing the Out-of-Hospital Extraglottic Airway Device. Ann Emerg Med. 2019;74(3):416-422. PubMed

4.Laurin EG, Wolfson B, Grayzel J. Extraglottic devices for emergency airway management in adults. In: Post TW, ed. UpToDate. Waltham (MA): UpToDate; 2024: https://www.uptodate.com.

5.Doyle DJ, Hagberg CA, Crowley M. Supraglottic airways (SGAs) for airway management for anesthesia in adults. In: Post TW, ed. UpToDate. Waltham (MA): UpToDate; 2024: https://www.uptodate.com.

6.Wang HE, Benger JR. Endotracheal intubation during out-of-hospital cardiac arrest: New insights from recent clinical trials. J Am Coll Emerg Physicians Open. 2020;1(1):24-29. PubMed

7.Stuby L, Jampen L, Sierro J, et al. Effect of Early Supraglottic Airway Device Insertion on Chest Compression Fraction during Simulated Out-of-Hospital Cardiac Arrest: Randomised Controlled Trial. J Clin Med. 2022;11(1):217. PubMed

8.Forestell B, Ramsden S, Sharif S, et al. Supraglottic Airway Versus Tracheal Intubation for Airway Management in Out-of-Hospital Cardiac Arrest: A Systematic Review, Meta-Analysis, and Trial Sequential Analysis of Randomized Controlled Trials. Crit Care Med. 2024;52(2):e89-e99. PubMed

9.Yang Z, Liang H, Li J, et al. Comparing the efficacy of bag-valve mask, endotracheal intubation, and laryngeal mask airway for subjects with out-of-hospital cardiac arrest: an indirect meta-analysis. Ann. 2019;7(12):257. PubMed

10.Benger JR, Kirby K, Black S, et al. Supraglottic airway device versus tracheal intubation in the initial airway management of out-of-hospital cardiac arrest: the AIRWAYS-2 cluster RCT. Health Technol Assess. 2022;26(21):1-158. PubMed

11.Lonvik MP, Elden OE, Lunde MJ, Nordseth T, Bakkelund KE, Uleberg O. A prospective observational study comparing two supraglottic airway devices in out-of-hospital cardiac arrest. BMC Emerg Med. 2021;21(1):51. PubMed

12.Price P, Laurie A, Plant E, Chandra K, Pishe T, Brunt K. Comparing the First-Pass Success Rate of the King LTS-D and the i-gel Airway Devices in Out-of-Hospital Cardiac Arrest. Cureus. 2022;14(11):e30987. PubMed

13.Smida T, Menegazzi J, Crowe R, Scheidler J, Salcido D, Bardes J. A Retrospective Nationwide Comparison of the iGel and King Laryngeal Tube Supraglottic Airways for Out-of-Hospital Cardiac Arrest Resuscitation. Prehosp Emerg Care. 2024;28(2):193-199. PubMed

14.Smida T, Menegazzi J, Scheidler J, Martin PS, Salcido D, Bardes J. A retrospective comparison of the King Laryngeal Tube and iGel supraglottic airway devices: A study for the CARES surveillance group. Resuscitation. 2023;188:109812. PubMed

15.Edwards T, Williams J, Cottee M. Influence of prehospital airway management on neurological outcome in patients transferred to a heart attack centre following out-of-hospital cardiac arrest. Emerg Med Australas. 2019;31(1):76-82. PubMed

16.Jarvis JL, Wampler D, Wang HE. Association of patient age with first pass success in out-of-hospital advanced airway management. Resuscitation. 2019;141:136-143. PubMed

17.Kim TY, Kim S, Han SI, et al. Gastric Inflation in Prehospital Cardiopulmonary Resuscitation: Aspiration Pneumonia and Resuscitation Outcomes. Rev Cardiovasc Med. 2023;24(7):198. PubMed

18.Levi D, Hoogendoorn J, Samuels S, et al. The i-gel((R)) supraglottic airway device compared to endotracheal intubation as the initial prehospital advanced airway device: A natural experiment during the COVID-19 pandemic. J Am Coll Emerg Physicians Open. 2024;5(2):e13150. PubMed

19.Matic I, Pajic Matic I, Marcikic M, Jurjevic M, Zanko B, Dosen I. Comparison of Different out-of-Hospital Airway Management Techniques in Patients with Cardiac Arrest in Slavonia Region. Acta Clin. 2021;60(4):590-594. PubMed

20.Nichols M, Fouche PF, McPherson T, Evens T, Bendall J. Lessons from the first two years of a new out-of-hospital airway registry in New South Wales. Paramedicine. 2023;20(5):152-160.

21.Jarvis JL, Panchal AR, Lyng JW, et al. Evidence-Based Guideline for Prehospital Airway Management. Prehosp Emerg Care. 2024;28(4):545-557. PubMed

22.Liberati A, Altman DG, Tetzlaff J, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. J Clin Epidemiol. 2009;62(10):e1-e34. PubMed

23.Berkman ND, Lohr KN, Ansari M, et al. AHRQ Methods for Effective Health Care Grading the Strength of a Body of Evidence When Assessing Health Care Interventions for the Effective Health Care Program of the Agency for Healthcare Research and Quality: An Update. Methods Guide for Effectiveness and Comparative Effectiveness Reviews. Rockville (MD): Agency for Healthcare Research and Quality (US); 2008.

24.Gage CB, Powell JR, Bosson N, et al. Evidence-Based Guidelines for Prehospital Airway Management: Methods and Resources Document. Prehosp Emerg Care. 2024;28(4):561-567. PubMed

25.Shea BJ, Reeves BC, Wells G, et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. BMJ. 2017;358:j4008. PubMed

26.Downs SH, Black N. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health. 1998;52(6):377-384. PubMed

27.Agree Next Steps Consortium. The AGREE II Instrument. Hamilton (ON): AGREE Enterprise; 2017: https://www.agreetrust.org/wp-content/uploads/2017/12/AGREE-II-Users-Manual-and-23-item-Instrument-2009-Update-2017.pdf. Accessed 2024 Aug 23.

28.Grossestreuer AV, Abella BS, Sheak KR, et al. Inter-rater reliability of post-arrest cerebral performance category (CPC) scores. Resuscitation. 2016;109:21-24. PubMed

29.Broderick JP, Adeoye O, Elm J. Evolution of the Modified Rankin Scale and Its Use in Future Stroke Trials. Stroke. 2017;48(7):2007-2012. PubMed

30.van Hout B, Janssen MF, Feng YS, et al. Interim scoring for the EQ-5D-5L: mapping the EQ-5D-5L to EQ-5D-3L value sets. Value Health. 2012;15(5):708-715. PubMed

31.Schauer SG, Tapia AD, Jeschke EA, et al. Expert Consensus Panel Recommendations for Selection of the Optimal Supraglottic Airway Device for Inclusion to the Medic's Aid Bag. Med J (Ft Sam Houst Tex). 2023(Per 23-1/2/3):97-102.

32.Australian and New Zealand Committee on Resuscitation. Guideline 11.6 – Equipment and Techniques in Adult Advanced Life Support. ANZCOR; 2024: https://www.anzcor.org/assets/anzcor-guidelines/guideline-11-6-equipment-and-techniques-in-adult-advanced-life-support-248.pdf. Accessed 2024 Aug 14.

33.Carlson JN, Colella MR, Daya MR, et al. Prehospital Cardiac Arrest Airway Management: An NAEMSP Position Statement and Resource Document. Prehosp Emerg Care. 2022;26:54-63. PubMed

34.Lyng JW, Baldino KT, Braude D, et al. Prehospital Supraglottic Airways: An NAEMSP Position Statement and Resource Document. Prehosp Emerg Care. 2022;26(sup1):32-41.

35.National Association of State Emergency Medical Services Officials. Model Clinical Guideline: Prehospital Airway Management. Falls Church (VA): NASEMO; 2023: https://nasemso.org/wp-content/uploads/Model-Clinical-Guideline-Prehospital-Airway-Management.pdf. Accessed 2024 Aug 14.

36.Callaway CW, Soar J, Aibiki M, et al. Part 4: Advanced Life Support: 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2015;132(16 Suppl 1):S84-145. PubMed

Appendix 1: Detailed Methods and Selection of Included Studies

Please note that this appendix has not been copy-edited.

Literature Search Methods

An information specialist conducted a literature search on key resources including MEDLINE, the Cochrane Database of Systematic Reviews, the International HTA Database, the websites of Canadian and major international health technology agencies, as well as a focused internet search. The search approach was customized to retrieve a limited set of results, balancing comprehensiveness with relevancy. The search strategy comprised both controlled vocabulary, such as the National Library of Medicine’s MeSH (Medical Subject Headings), and keywords. Search concepts were developed based on the elements of the research questions and selection criteria. The main search concepts were extraglottic airway devices and the prehospital setting. The search was completed on August 8, 2024, and limited to English-language documents published since January 1, 2019.

Selection Criteria and Methods

Two reviewers independently screened citations and selected studies, with 1 reviewer required to include or exclude a study. In the first level of screening, titles and abstracts were reviewed and potentially relevant articles were retrieved and assessed for inclusion. The final selection of full-text articles was based on the inclusion criteria presented in Table 1.

Exclusion Criteria

Articles were excluded if they met any of the following criteria:

• did not meet the selection criteria outlined in Table 1

• were duplicate publications

• were published before 2019

• were systematic reviews in which all relevant studies were captured in other more recent or more comprehensive systematic reviews

• were primary studies captured in 1 or more included systematic reviews

• were studies on airway devices during in-hospital, or nonemergency or scheduled surgeries and procedures

• were studies on intubating laryngeal mask airways (e.g., laryngeal mask airway Fastrach, Air-Q).

Guidelines with unclear or alternative methodology were not included in the text, but their characteristics and findings are presented in Appendix 1.

Critical Appraisal of Individual Studies

Two reviewers conducted critical appraisal. The included publications were critically appraised by 1 reviewer using the following tools as a guide: A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2)²⁵ for systematic reviews, the Downs and Black checklist²⁶ for randomized and nonrandomized studies, and the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument²⁷ for guidelines. Summary scores were not calculated for the included studies; rather, the strengths and limitations of each included publication were described narratively.

Appendix 2: Selection of Included Studies

Please note that this appendix has not been copy-edited.

Figure 1: Selection of Included Studies

Appendix 3: Characteristics of Included Publications

Please note that this appendix has not been copy-edited.

Table 3: Characteristics of Included Systematic Reviews

BVM = bag valve mask; ETI = endotracheal intubation; LMA = laryngeal mask airway; LT = laryngeal tube; NR = not reported; NRS = nonrandomized study; OHCA = out-of-hospital cardiac arrest; RCT = randomized controlled trial; ROSC = return of spontaneous circulation; SGA = supraglottic airway; vs. = versus.

Table 4: Characteristics of Included Primary Clinical Studies

BVM = bag valve mask; CPC = cerebral performance category; CPR = cardiopulmonary resuscitation; ED = emergency department; EMT = emergency medical technicians; EMS = emergency medical system; EQ-5D-5L = EuroQol 5-Dimension 5-level; ETCO2 = end-tidal carbon dioxide; ETI = endotracheal intubation; GI = gastric inflation; IQR = interquartile range; LT = laryngeal tube; NHS = National Health Service; NIHR = National Institute for Health and Care Research; NR = not reported; OHCA = out-of-hospital cardiac arrest; SD = standard deviation; SGA = supraglottic airway devices; ROSC = return of spontaneous circulation; vs. = versus.

Table 5: Characteristics of Included Guideline

AHRQ = Agency for Health Care Research and Quality; EMS = emergency medical services; GRADE = Grading of Recommendations Assessment, Development, and Evaluation; NR = not reported; SR = systematic review.

Appendix 4: Critical Appraisal of Included Publications

Please note that this appendix has not been copy-edited.

Table 6: Strengths and Limitations of Systematic Reviews Using AMSTAR 2²⁵

AMSTAR 2 = A Measurement Tool to Assess Systematic Reviews 2; vs. = versus.

Table 7: Strengths and Limitations of Clinical Studies Using the Downs and Black Checklist²⁶

ED = emergency department; ICU = intensive care unit; SGA = supraglottic airway device.

Table 8: Strengths and Limitations of Guideline Using AGREE II²⁷

AGREE II = Appraisal of Guidelines for Research and Evaluation II; AHRQ = Agency for Health Care Research and Quality.

Appendix 5: Main Study Findings

Please note that this appendix has not been copy-edited.

Table 9: Summary of First-Pass Success Outcomes Between Supraglottic Airway Devices

aOR = adjusted odds ratio; CI = confidence interval; CPR = cardiopulmonary resuscitation; ECG = electrocardiogram; FPS = first-pass success; NR = not reported; NRS = nonrandomized study; OHCA = out-of-hospital cardiac arrest; OR = odds ratio; RCT = randomized controlled trial; RR = risk ratio; SR = systematic review.

^aModels adjusted for age, sex, initial ECG rhythm, witnessed status, bystander CPR, response interval, OHCA location, and whether patients received supraglottic airway devices after failed intubation attempts (rescue supraglottic airway devices).

Table 10: Summary of Other Success Rates Between Supraglottic Airway Devices

CI = confidence interval; LMA = laryngeal mask airway; LT = laryngeal tube; NRS = nonrandomized study; RCT = randomized controlled trial; RR = risk ratio; SD = standard deviation; SR = systematic review.

Table 11: Summary of Survival Outcomes Between Supraglottic Airway Devices

CI = confidence interval; CPC = Cerebral Performance Category; CPR = cardiopulmonary resuscitation; ECG = electrocardiogram; EMS = emergency medical service; LT = laryngeal tube; NR = not reported; NRS = nonrandomized study; OHCA = out-of-hospital cardiac arrest; RCT = randomized controlled trial; SR = systematic review.

^aModels adjusted for age, sex, initial ECG rhythm, witnessed status, bystander CPR, response interval, OHCA location, and whether patients received supraglottic airway devices after failed intubation attempts (rescue supraglottic airway devices). (p.194)¹³

^bAdjusted for age, sex, calendar year of OHCA, initial ECG rhythm (shockable, nonshockable), witnessed status (unwitnessed, witnessed by bystander, witnessed by 9 to 1-1 responder), bystander CPR, response interval, and OHCA location (home or residence, public, nursing home or health care facility) (p.2)¹⁴

^cCPC is a 5-point scale assessing neurologic functions after a resuscitation attempt. A CPC score of 1 or 2 is generally defined as a good outcome: 1 = good cerebral performance (conscious, alert, able to work, might have mild neurologic or psychologic deficit); 2 = mild cerebral disability (conscious, sufficient cerebral function for independent activities of daily life, able to work in sheltered environment). Scores of 3 to 5 mean poor outcomes: 3 = severe neurologic disability (conscious, dependent on others for daily support because of impaired brain function); 4 = comma or vegetative state (any degree of coma without the presence of all brain death criteria); 5 = brain death.^14,28

Table 12: Summary of Return of Spontaneous Circulation Outcomes Between Supraglottic Airway Devices

CI = confidence interval; NR = not reported; NRS = nonrandomized study; RCT = randomized controlled trial; SR = systematic review.

Table 13: Summary of Rearrest Outcomes – I-Gels Compared With King Laryngeal Tubes

CI = confidence interval; CPR = cardiopulmonary resuscitation; NRS = nonrandomized study.

Note: Rearrest was defined as having had “both documented prehospital ROSC (return of spontaneous circulation) and met one or more of the following conditions: (1) documented pulseless rhythms (PEA, asystole, ventricular fibrillation/tachycardia, torsades de points, unknown AED shockable/nonshockable rhythm) at emergency department (ED) arrival. (2) Documented defibrillation attempts, resumption of manual/- mechanical CPR, or 1 milligram bolus dose epinephrine administration after documented ROSC. (3) Greater than one documented CPR discontinuation” (p.194).¹³

Table 14: Summary of End-Tidal Carbon Dioxide Levels – I-Gels Compared With King Laryngeal Tubes

CI = confidence interval; ETCO2 = end-tidal carbon dioxide; NRS = non = randomized study.

Table 15: Summary of Complications in Supraglottic Airway Devices – I-Gels Compared With King Laryngeal Tubes

NRS = nonrandomized study.

Table 16: Summary of Reported Difficulty of Insertion – I-Gel Compared With King Laryngeal Tube

CI = confidence interval; NRS = nonrandomized study; RR = risk ratio.

Table 17: Summary of First-Pass Success Outcomes – Supraglottic Airway Devices Compared With Endotracheal Intubation

AAM = advanced airway management; ADP = adjusted difference in proportions of patients ; aOR = adjusted odds ratio; CI = confidence interval; EMS = emergency medical services; ETI = endotracheal intubation; FPS = first-pass success; NR = not reported ; OR = odds ratio; RR = risk ratio; RSI = rapid sequence intubation; SAI = sedation assisted intubation; SGA = supraglottic airway device.

Note: Jarvis et al. (2019) included multiple types of SGAs; refer to the baseline characteristics table for more details.

^aModel adjusted for indication, use of medications (rapid sequence intubation and sedation assisted intubation), sex, and patient identity.

Table 18: Summary of Other Success Rates and Placement Attempts – I-Gel Compared With Endotracheal Intubation

CI = confidence interval; ETI = endotracheal intubation; NR = not reported; NRS = nonrandomized study; RCT = randomized controlled trial.

Table 19: Summary of Return of Spontaneous Circulation Outcomes – Supraglottic Airway Devices Compared With Endotracheal Intubation

AAM = advanced airway management; ADP = adjusted difference in proportions of patients; CI = confidence interval; ED = emergency department; ETI = endotracheal intubation; LMA-S = laryngeal mask airway supreme; ROSC = return of spontaneous circulation; MA = meta-analysis; NR = not reported; NRS = nonrandomized study; OR = odds ratio; RCT = randomized controlled trial; RR = risk ratio; SR = systematic review.

Note: The results from Forestell et al. (2024) have been reported as individual studies as well as the pooled findings. This is to allow for reviewing the results of studies by specific types of supraglottic airway devices as well as combined.

Table 20: Summary of Time-Related Outcomes – Supraglottic Airway Devices Compared With Endotracheal Intubation

CI = confidence interval; ETI = endotracheal intubation; MD = mean difference; NRS = nonrandomized study; RCT = randomized controlled trial; SD = standard deviation; SGA = supraglottic airway device; SR = systematic review.

Note: The results from Forestell et al. (2024) have been reported as individual studies as well as the pooled findings. This is to allow for reviewing the results of studies by specific type of supraglottic airway devices as well as combined.

Table 21: Summary of Survival Outcomes – Supraglottic Airway Devices Compared With Endotracheal Intubation

ADP = adjusted difference in proportions of patients; CI = confidence interval; ED = emergency department; ETI = endotracheal intubation; HR = hazard ratio; IQR = interquartile range; MA = meta analysis ; NR= not reported ; NRS = nonrandomized study; OHCA = out-of-hospital cardiac arrest; OR = odds ratio; RCT = randomized controlled trial; RR = risk ratio; SD = standard deviation; SGA = supraglottic airway device; SR = systematic review.

Note: The results from Forestell et al. (2024) have been reported as individual studies as well as the pooled findings. This is to allow for reviewing the results of studies by specific type of supraglottic airway devices as well as combined.

Table 22: Summary of Functional Outcomes – I-Gel Compared With Endotracheal Intubation

ADP = adjusted difference in proportions of patients; aOR = adjusted odds ratio; CI = confidence interval; CPC = Cerebral Performance Category; CPR = cardiopulmonary resuscitation; ETI = endotracheal intubation; ITT = intention-to-treat; mRS = modified Rankin Scale; NR = not reported ; NRS = nonrandomized study; OHCA = out-of-hospital cardiac arrest; OR = odds ratio; RCT = randomized controlled trial; ROSC = return of spontaneous circulation ; RR = risk ratio; SR = systematic review.

^aCPC is a 5-point scale assessing neurologic functions after a resuscitation attempt. A CPC score of 1 or 2 is generally defined as a good outcome: 1 = good cerebral performance (conscious, alert, able to work, might have mild neurologic or psychologic deficit); 2 = mild cerebral disability (conscious, sufficient cerebral function for independent activities of daily life, able to work in sheltered environment). Scores of 3 to 5 mean poor outcomes: 3 = severe neurologic disability (conscious, dependent on others for daily support because of impaired brain function); 4 = comma or vegetative state (any degree of coma without the presence of all brain death criteria); 5 = brain death.^14,28

^bThe mRS is a 6-point scale measuring disability with scores ranging from 0 to 5: 0 = no symptoms; 1 = no significant disability (able to carry out all usual activities, despite some symptoms); 2 = slight disability (able to look after own affairs without assistance, but unable to carry out all previous activities); 3 = moderate disability (requires some help, but able to walk unassisted); 4 = moderately severe disability (unable to attend to own bodily needs without assistance, and unable to walk unassisted); 5 = Severe disability (requires constant nursing care and attention, bedridden, incontinent); 6 = dead.²⁹

Table 23: Summary of Ventilator-Free Days and Length of Stay – I-Gel Compared With Endotracheal Intubation

CI = confidence interval; ETI = endotracheal intubation; ICU = intensive care unit; NRS = nonrandomized study; RCT = randomized controlled trial.

^a“Ventilator-free days were calculated as “0” if the patient died within 28 days of mechanical ventilation or remained ventilated for more than 28 days. Ventilator-free days were calculated as “28 – X” if a patient was successfully liberated from mechanical ventilation X days from initiation” (p.4)¹⁸

Table 24: Summary of Quality of Life – I-Gel Compared With Endotracheal Intubation

CI = confidence interval; ETI = endotracheal intubation; IQR = interquartile range; NRS = nonrandomized study; OR = odds ratio; RCT = randomized controlled trial; SR = systematic review; VAS = Visual Analogue Scale.

Note: Berger et al. (2022) also reported comparisons between survivors and nonsurvivors, as well as analyses using worst-case and inputted-case scenarios. All were not statistically significant and are not presented here.

^aThe EQ-5D system measures health-related quality of life across 5 dimensions, including mobility, self-care, usual activities, pain and discomfort, and anxiety and depression. Responses to can be converted to a single index value, with 1 being the healthiest state.^10,30

^bThe EQ VAS is a self-rated scale measuring patients’ overall current health on a vertical visual analogue scale from 0 (worst imaginable health) to 100 (best imaginable health).^10,30

Table 25: Summary of Adverse Events – I-Gel Compared With Endotracheal Intubation

ADP = adjusted difference in proportions of patients; aOR = adjusted odds ratio; CI = confidence interval; ETI = endotracheal intubation; NR = not reported; NRS = nonrandomized study; OR = odds ratio; RCT = randomized controlled trial; SR = systematic review.

^aAuthors reported regurgitation and aspiration before the i-gel or ETI attempt; they have not been reported here to focus on adverse events that may have been due to the intervention. Authors noted that the proportion of patients experiencing either event before the advanced airway management attempt was larger in the tracheal intubation group than ETI group, which was the reverse of the outcomes during or after the advanced airway management attempt; however, these differences were not formally tested.

^bAuthors noted that there are some cardiac patients who cannot experience effective ventilation with a supraglottic airway device, and ETI may be the only way to experience effective ventilation.

Table 26: Summary of Recommendations in Included Guideline

AHRQ = Agency for Health Care Research and Quality; BVM = bag valve mask; ETI = endotracheal intubation; NA = not applicable; NRS = nonrandomized study; OHCA = out-of-hospital cardiac arrest; RCT = randomized controlled trial; ROSC = return of spontaneous circulation; SGA = supraglottic airway device; SR = systematic review.

Appendix 6: Overlap Between Included Systematic Reviews

Please note that this appendix has not been copy-edited.

Table 27: Overlap in Relevant Primary Studies Between Included Systematic Reviews

RQ = research question.

Note: Although both Carney et al. (2021) and Yang et al. (2018) included Benger et al. (2016), they reported on results from different comparisons. Carney et al. (2021) focused on comparisons between 2 types of supraglottic airway devices (i-gels and laryngeal mask airways), while Yang et al. (2018) reported on the comparisons between laryngeal mask airways and endotracheal intubation.

^aThis publication is based on the AIRWAYS-2 trial, which was also reported on in Benger et al. (2022).¹⁰

Appendix 7: Summary of Nonevidence-Based Guidelines

Please note that this appendix has not been copy-edited.

Below are compiled recommendations from 5 guidelines identified from the literature search that were considered to not be evidence-based due to unclear or nonsystematic methodologies. The guideline from the Committee on Tactical Combat Casualty Care³¹ suggested adding gel-cuffed supraglottic airway device and the laryngeal tube supraglottic airway device to the medics’ aid bag in the prehospital combat setting, while other guidelines^32-35 provided recommendations on general steps to use supraglottic airway devices. Characteristics of these guidelines were presented below in Table 28, and relevant recommendations were summarized in Table 29. No critical appraisal of these guidelines was conducted.

Table 28: Characteristics of Guidelines With Unclear or Alternative Methodology

ALS = advanced life support; ANZCOR = Australian and New Zealand Committee on Resuscitation; CoSTR = International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations; CoTCCC = Committee on Tactical Combat Casualty Care; EMS = Emergency Medical Services; NAEMSP = National Association of Emergency Medical Services Physicians; NASEMSO = National Association of State Emergency Medical Services Officials; NR = not reported; OHCA = out-of-hospital cardiac arrest; ROSC = return of spontaneous circulation; SGA = supraglottic airway device.

Table 29: Recommendations from Guidelines With Unclear or Alternative Methodology

ANZCOR = Australian and New Zealand Committee on Resuscitation; BVM = bag valve mask; CoTCCC = Committee on Tactical Combat Casualty Care; CPR = cardiopulmonary resuscitation; ETCO2 = end-tidal carbon dioxide; ETI = endotracheal intubation; ETT = endotracheal tube; NAEMSP = National Association of Emergency Medical Services Physicians; NASEMSO = National Association of State Emergency Medical Services Officials; NPA = nasopharyngeal airways; NR = not reported; OHCA = out-of-hospital cardiac arrest; OPA = oropharyngeal airways; PEEP = positive end expiratory pressure; SGA = supraglottic airway device.

^aThe evidence quality assessment and recommendation evaluation was likely not conducted by the ANZCOR but retrieved from a 2015 guideline from the International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations.³⁶

Appendix 8: References of Potential Interest

Please note that this appendix has not been copy-edited.

Systematic Reviews

Unclear Intervention

Amagasa S, Utsumi S, Moriwaki T, et al. Advanced airway management for pediatric out-of-hospital cardiac arrest: A systematic review and network meta-analysis. Am J Emerg Med. 2023;68():161-169.

Weihing VK, Crowe EH, Wang HE, Ugalde IT. Prehospital airway management in the pediatric patient: A systematic review. Acad Emerg Med. 2022;29(6):765-771. PubMed

Lavonas EJ, Ohshimo S, Nation K, et al. Advanced airway interventions for paediatric cardiac arrest: A systematic review and meta-analysis. Resuscitation. 2019;138():114-128.

Mixed or Alternative Intervention – Alternative Supraglottic Airway Devices

Wang CH, Lee AF, Chang WT, et al. Comparing Effectiveness of Initial Airway Interventions for Out-of-Hospital Cardiac Arrest: A Systematic Review and Network Meta-analysis of Clinical Controlled Trials. Ann Emerg Med. 2020;75(5):627-636. PubMed

Nonrandomized Studies

Unclear Intervention

Weigeldt M, Schulz-Drost S, Stengel D, Lefering R, Treskatsch S, Berger C. In-hospital mortality after prehospital endotracheal intubation versus alternative methods of airway management in trauma patients. A cohort study from the TraumaRegister DGU R. Eur. 2024;20():20.

Yoshimura S, Kiguchi T, Nishioka N, et al. Association of pre-hospital tracheal intubation with outcomes after out-of-hospital cardiac arrest by drowning comparing to supraglottic airway device: A nationwide propensity score-matched cohort study. Resuscitation. 2024;197():110129.

Nakayama R, Bunya N, Uemura S, Sawamoto K, Narimatsu E. Prehospital Advanced Airway Management and Ventilation for Out-of-Hospital Cardiac Arrest with Prehospital Return of Spontaneous Circulation: A Prospective Observational Cohort Study in Japan. Prehosp Emerg Care. 2024;28(3):470-477. PubMed

Song SR, Kim KH, Park JH, Song KJ, Shin SD. Association between prehospital airway type and oxygenation and ventilation in out-of-hospital cardiac arrest. Am J Emerg Med. 2023;65():24-30.

Tjerkaski J, Hermansson T, Dillenbeck E, et al. Strategies of Advanced Airway Management in Out-of-Hospital Cardiac Arrest during Intra-Arrest Hypothermia: Insights from the PRINCESS Trial. J. 2022;11(21):28.

Hongo T, Yumoto T, Naito H, Mikane T, Nakao A. Impact of different medical direction policies on prehospital advanced airway management for out-of hospital cardiac arrest patients: A retrospective cohort study. Resusc Plus. 2022;9():100210.

Jung E, Ro YS, Ryu HH, Shin SD. Association of prehospital airway management technique with survival outcomes of out-of-hospital cardiac arrest patients. PLoS One. 2022;17(6):e0269599. PubMed

Wang HE, Jaureguibeitia X, Aramendi E, et al. Airway strategy and ventilation rates in the pragmatic airway resuscitation trial. Resuscitation. 2022;176():80-87.

Chan JJ, Goh ZX, Koh ZX, et al. Clinical evaluation of the use of laryngeal tube versus laryngeal mask airway for out-of-hospital cardiac arrest by paramedics in Singapore. Singapore Med J. 2022;63(3):157-161. PubMed

Le Bastard Q, Rouzioux J, Montassier E, et al. Endotracheal intubation versus supraglottic procedure in paediatric out-of-hospital cardiac arrest: a registry-based study. Resuscitation. 2021;168():191-198.

Kim S, Lee DE, Moon S, et al. Comparing the neurologic outcomes of patients with out-of-hospital cardiac arrest according to prehospital advanced airway management method and transport time interval. Clin. 2020;7(1):21-29. PubMed

van Tulder R, Schriefl C, Roth D, et al. Laryngeal Tube Practice in a Metropolitan Ambulance Service: A Five-year Retrospective Observational Study (2009-2013). Prehosp Emerg Care. 2020;24(3):434-440. PubMed

Shekhar A, Blumen I, Narula J. ENDOTRACHEAL INTUBATION VERSUS SUPRAGLOTTIC AIRWAY INSERTION IN CARDIAC ARREST: THE PREHOSPITAL EXPERIENCE. Journal of the American College of Cardiology (JACC). 2021;77(18):3250-3250.

Mixed or Alternative Intervention – Alternative Supraglottic Airway Devices

Bartos JA, Clare Agdamag A, Kalra R, et al. Supraglottic airway devices are associated with asphyxial physiology after prolonged CPR in patients with refractory Out-of-Hospital cardiac arrest presenting for extracorporeal cardiopulmonary resuscitation. Resuscitation. 2023;186():109769.

Tham LP, Fook-Chong S, Binte Ahmad NS, et al. Pre-hospital airway management and survival outcomes after paediatric out-of-hospital cardiac arrests. Resuscitation. 2022;176():9-18.

Ryan KM, Bui MD, Dugas JN, Zvonar I, Tobin JM. Impact of prehospital airway interventions on outcome in cardiac arrest following drowning: A study from the CARES Surveillance Group. Resuscitation. 2021;163():130-135.

Nwanne T, Jarvis J, Barton D, Donnelly JP, Wang HE. Advanced airway management success rates in a national cohort of emergency medical services agencies. Resuscitation. 2020;146():43-49.

Ostermayer DG, Camp EA, Langabeer JR, et al. Impact of an Extraglottic Device on Pediatric Airway Management in an Urban Prehospital System. West J Emerg Med. 2019;20(6):962-969. PubMed