Article

Advanced airway management in out of hospital cardiac arrest: A systematic review and meta-analysis

a b s t r a c t

Objectives: To assess the difference in Survival and neurological outcomes between Endotracheal tube intu- bation and Supraglottic airway devices used during out-of-hospital cardiac arrest (OHCA).

Methods: A systematic search of five databases was performed by two independent reviewers until September 2018. Included studies reported on (1) OHCA or cardiopulmonary resuscitation, and (2) endotracheal intubation versus supraglottic airway device intubation. Exclusion criteria (1) stimulation studies, (2) selectively included/ excluded patients, (3) in-hospital cardiac arrest. Odds Ratios (OR) with random effect modelling was used. Pri- mary outcomes: (1) return of spontaneous circulation (ROSC), (2) Survival to hospital admission, (3) survival to hospital discharge, (4) discharge with a Neurologically intact state.

Results: Twenty-nine studies (n = 539,146) showed that overall, ETT use resulted in a heterogeneous, but signif- icant increase in ROSC (OR = 1.44; 95%CI = 1.27 to 1.63; I2 = 91%; p b 0.00001) and Survival to admission (OR = 1.36; 95%CI = 1.12 to 1.66; I2 = 91%; p = 0.002). There was no significant difference in survival to discharge or neurological outcome (p N 0.0125). On sensitivity analysis of RCTs, there was no significant difference in ROSC, survival to admission, survival to discharge or neurological outcome (p N 0.0125). On analysis of automated chest compression, without heterogeneity, ETT provided a significant increase in ROSC (OR = 1.55; 95%CI = 1.20 to 2.00; I2 = 0%; p = 0.0009) and survival to admission (OR = 2.16; 95%CI = 1.54 to 3.02; I2 = 0%; p b

0.00001).

Conclusions: The overall heterogeneous benefit in survival with ETT was not replicated in the low risk RCTs, with no significant difference in survival or neurological outcome. In the presence of automated chest compressions, ETT intubation may result in Survival benefits.

(C) 2018

Introduction

Out of Hospital Cardiac Arrest (OHCA) is the third leading cause of death in the United States and represents a significant Public health concern [1]. OHCA is a heterogeneous and time critical condition with a variety of aetiologies, and little is known about the benefits of various interventions [2]. Previous guidelines have reduced the emphasis on en- dotracheal intubation as an airway Management strategy, although op- timal airway management remains uncertain [2].

* Corresponding author at: School of Medicine, University of Queensland, A: 12 Macon St, Birtinya, QLD 4575, Australia.

E-mail address: [email protected] (L. White).

advanced airway management strategies for OHCA include endotra- cheal tube (ETT) intubation or use of Supraglottic airway devices. ETT intubation is traditionally considered a definitive airway, although greater skill is required for its placement and the process of securing the airway may be associated with unrecognized misplacement of the tube, increased number of attempts and interruptions to chest compres- sions [3,4]. Since previous meta-analyses [5], a number of studies have renewed interest in establishing optimal airway management strategies for OHCA [6-8].

The aim of this study is to perform the most thorough and up to date systematic review and meta-analysis to assess the difference in survival and neurological outcomes between ETT intubation and SGA devices for advanced airway management in OHCA.

https://doi.org/10.1016/j.ajem.2018.09.045

0735-6757/(C) 2018

L. White et al. / American Journal of Emergency Medicine 36 (2018) 22982306 2299

Methods

This study was registered with the International Prospective Regis- ter of Systematic Reviews (PROSPERO; CRD42018100126). The Pre- ferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed.

Search strategy

A systematic search was performed by two independent reviewers (LW & RV). The search included SCOPUS, PubMed, Medline, Cochrane Central Register of Controlled Trials and Web of Science. This search was conducted from the inception of the databases until September 2018. The search was performed using Medical Subject Headings (MeSH) terms, which included: “Airway management” plus “cardiac ar- rest”; “Emergency Medical Service” plus “out-of-hospital cardiac arrest” plus “airway management”. The term “Airway Management” consists of MeSH terms “intubation”, “laryngeal mask” and “positive pressure res- piration”. “Emergency Medical Service” consists of MeSH terms “ambu- lance” and “prehospital emergency care“. For completeness, a manual reference check of a recent review (5) and other accepted papers was performed to identify any additional studies.

Eligibility criteria

For a study to be included in this meta-analysis the authors were re- quired to report on (1) cardiac arrest or cardiopulmonary resuscitation

(2) endotracheal intubation versus supraglottic airway device intuba- tion. Supraglottic airway devices included laryngeal masks and laryn- geal tubes. Clinical outcomes of interest were required to be presented (no systematic review or meta-analysis). Only out of hospital cardiac ar- rest studies were eligible for inclusion. Two reviewers (LW & RV) assessed agreed upon each study for inclusion in this systematic review. All study designs were eligible for inclusion.

Exclusion criteria

Manikin and simulation studies were excluded. Studies that selec- tively included or excluded patients were ineligible, for example witnessed cardiac arrest patients. In hospital cardiac arrests were not el- igible for inclusion.

Outcomes

The primary outcomes of interest included (1) return of spontane- ous circulation (ROSC) (2) survival to hospital admission (3) survival to hospital discharge (4) survival to discharge with a cognitively intact state. An intact neurological state was defined as a cerebral performance category one or two or Modified Rankin scale <= 3. All included studies were screened for additional common outcomes for post hoc analysis.

Data collection and extraction

Two reviewers (LW and RV) independently extracted data from each article that met the inclusion criteria. The data extracted from each study included the study design, sample size, airway device, cause of cardiac arrest, registry utilized and outcome measures. The data collected by each reviewer was then compared for homogeneity.

Risk of bias

Two independent reviewers assessed each study for risk of bias. Two separate tools were used. Randomised controlled trials (RCTs) were assessed for risk of bias and methodological quality using the Cochrane Collaboration’s tool for assessing the risk of bias [9]. Non-randomised were assessed using the ROBINS-I tool [10].

Statistical analyses

The combined data was analysed using RevMan 5.3 software (The Nordic Cochrane Centre, Copenhagen, Denmark). Dichotomous out- comes were analysed using an Odds Ratio (OR) with 95% confidence in- terval (CI). The Mantel-Haenszel (M-H) random effects model was used. The absolute difference between the two groups was measured utilizing the Risk difference with 95%CIs. Heterogeneity was assess using the I2 statistic, with an I2 N 50% indicating significant heterogene- ity. Given we intended to assess four outcome measures, we used the Bonferroni method to minimise the risk of type one errors. Therefore a p value of b0.0125 provided evidence of significant OR.

Subgroup and sensitivity analyses

Pre-specified sensitivity analyses were performed based on care provider, manual chest compressions, automatic chest compressions, laryngeal mask use, laryngeal tube use, cause of arrest, location of arrest and study quality. In the case of studies utilizing duplicate databases, two authors (LW & RV) independently decided which duplicates to ex- clude on sensitivity analysis. Any disagreements were settled by a third reviewer (TM).

Assessment of quality of evidence

The quality of evidence and confidence in estimates of effect were assessed using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach [11]. This approach was per- formed by considering the within study risk of bias, heterogeneity be- tween studies, effect estimate precision and the risk of publication bias. Publication bias and small-study effects were assessed via funnel plots of standard errors versus effect estimates. This study was written in accordance with the Meta-analysis Of Observational Studies in Epide- miology (MOOSE) checklist [12].

Results

Literature search results

The systematic literature search yielded 29 studies for inclusion in this meta-analysis (Fig. 1). The initial electronic search identified 1494 studies and a further 17 were identified on manual reference and cita- tion searches. Following the removal of duplicate records and title screening, 109 abstracts were reviewed. Sixty-three full text studies were reviewed to identify the 26 included studies. There were no dis- agreements between the two authors performing the search review. In total data from 539,146 patients were included (Table 1). Details on the individual excluded studies are listed in Table S1 [13-48].

Risk of bias

Each study was then screened for risk of bias and methodological quality using the Cochrane Collaboration’s tool for assessing the risk of bias for RCTs and the ROBINS-I tool for non-randomised studies (Table S2). Included in this meta-analysis were five low risk RCTS, eight moderate risk non-randomised studies and sixteen serious risk non-randomised studies.

Database duplication and outcome measures

Of the twenty-six studies included, eight overlapping registry trials were found. Various studies performed in Japan were included in this meta-analysis [6,31,56,58,63,66,67,69]. However, due to the time span of the Fukuda et al. study (2005-2014 inclusive), which included Japan-wide data, some studies [31,58,63,67,69] were omitted to avoid the duplication of information. Despite taking place within the same

2300 L. White et al. / American Journal of Emergency Medicine 36 (2018) 22982306

heterogeneity on analysis of low risk RCTs (OR = 0.92; 95%CI = 0.80 to 1.05; I2 = 23%; p = 0.22).

Survival to admission

Fourteen studies (n = 51,756) investigated survival to admission, with a significant increase with ETT (OR = 1.36; 95%CI = 1.12 to 1.66; I2 = 91%; p = 0.002; Table 3) [7,14,49,50,52,53,55,58-61,64,70,71]. The

funnel plot of the overall result was skewed to the right (Fig. S2). Based on the GRADE framework this was judged to be very low quality evi- dence. There was no change in significance or heterogeneity with removal of duplicate databases. On sensitivity analysis for resuscitation variables LMA and laryngeal tube, there was no significant difference with signifi- cant heterogeneity (Table 3). Without significant heterogeneity, there was a significant increase in survival to admission with ETT during auto- mated chest compressions (OR = 2.16; 95%CI = 1.54 to 3.02; I2 = 0%; p b 0.00001). On analysis of the low risk RCTs there was no significant difference between ETT and SGA (OR = 0.97; 95%CI = 0.68 to 1.09; I2 = 0%; p = 0.59).

Survival to discharge

Fig. 1. Study identification algorithm. This diagram outlines the filtering process from the literature search through to study inclusion.

time span as the Fukuda study, studies by Hasegawa et al. and Takei et al. were included within the subgroup analysis. These studies pro- vided information regarding patient ROSC prior to hospital arrival, and also additional data from the 2004 to 2005 period, respectively. Within each subgroup analysis the omitted studies from overlapping registries were eligible for inclusion if in lieu of results from Fukuda et al. or Hasegawa et al. and Takei et al. All studies were individually screened and no additional outcomes were identified for post-hoc analysis.

ROSC

Twenty-three studies (n = 397,158) investigated the effect of ad- vanced airway management on ROSC showing a significant increase with ETT (OR = 1.44; 95%CI = 1.27 to 1.63; I2 = 91%; p b 0.00001;

Table 2) [6,7,14,31,47,49-53,55-59,61-70,72]. The funnel plot of the overall result was skewed to the right (Fig. S1). Based on the GRADE framework this was judged to be very low quality evidence. There was no change in significance or heterogeneity with removal of dupli- cate databases. On subgroup analysis for resuscitation variables EMT provider and manual chest compressions remained significantly in fa- vour of ETT (p b 0.0125) with significant heterogeneity. The only out- come to have a significant increase in ROSC without heterogeneity was cardiac arrest using automated chest compressions (OR = 1.55; 95%CI = 1.20 to 2.00; I2 = 0%; p = 0.0009). On analysis of moderate and serious risk studies, the significant benefit of ETT with significant heterogeneity remained. The significant effect was lost without

Twenty-two studies (n = 440,564) investigated survival to dis- charge with no significant difference with ETT compared to SGA (OR = 1.28; 95%CI = 1.02 to 1.60; I2 = 96%; p = 0.03; Table 4)

[6,7,14,47,50-58,60,61,63,65-68,70-72]. The funnel plot of the over- all result was skewed to the right (Fig. S3). Based on the GRADE framework this was judged to be very low quality evidence. There was no change in significance or heterogeneity with removal of du- plicate databases. The subgroup analysis there was no change in non-significance with Laryngeal tubes, whereas the LMA subgroup had reached significance over ETT with heterogeneity (OR = 1.80; 95%CI = 1.14 to 2.83; I2 = 85%; p = 0.01) (Table 4). Subgroup anal- ysis for automated chest compressions was unable to be performed. There was no significant difference in survival to discharge in the low risk RCTs (OR = 0.90; 95%CI = 0.68 to 1.20; I2 = 70%; p = 0.49;

Table 4).

Survival to discharge with a neurologically intact state

Fourteen studies (n = 438,261) showed no significant difference (p N 0.0125) in discharge with a neurologically intact state (p = 0.16; Table 5) [6,7,47,51,56,58,59,61,63,65,67,68,70,72]. The funnel plot of

the overall result was skewed to the right (Fig. S4). Based on the GRADE framework this was judged to be very low quality evidence. This remained unchanged based on removal of duplicate studies, EMT provider, manual chest compressions, LMA use and laryngeal tube use (Table 5). When separated into low, moderate and serious risk studies, the effect remained non-significant.

Discussion

This was the largest and most up to date systematic review and meta-analysis on airway management in OHCA, with 29 studies and 539,146 patients included. Overall, ETT demonstrated better early sur- vival rates (ROSC and survival to admission) than SGA devices. Despite the improved early survival rates, there was no significant in longer term outcomes such as survival to discharge and neurological function at discharge from hospital. The clinical application of the overall im- provements in early survival with the use of ETT is limited due to the significant heterogeneity (I2 = 91%). This reflects the multifactorial na- ture of both cardiac arrest aetiology and management. For this reason multiple sensitivity analyses were performed.

The first sensitivity analysis performed was to control for the skill level of care providers, thus an analysis including EMT providers was undertaken. Again, the initial overall increase in early survival outcomes

Table 1

L. White et al. / American Journal of Emergency Medicine 36 (2018) 22982306

2301

Study characteristics.

Study

Study design

Sample (ETT/SGA)

Cause of OOHCA

SGA employed

Registry utilized (year)

Outcomes

Risk of bias?

Becker et al. [49]

Retrospective Cohort

126 (84/42)

All causes

Not specified

N/A

ROSC
  • Survival to admission
  • Serious

    Benger et al. [14]

    RCT

    615 (209/406)

    Non-traumatic

    i-Gel, LMA Supreme

    N/A

    ROSC
  • Survival to
  • Low

    admission

    3. Survival to discharge

    Benger et al. [70]

    RCT

    9296

    Non-traumatic

    i-Gel

    N/A

    1. ROSC

    Low

    (4410/4886)

    1. Survival to

    Bernhard et al.

    Retrospective

    22,350

    All causes

    Not specified

    German Resuscitation Registry (2010-2016)

    admission

    2. Survival to discharge

    2. Neurological outcome

    3. ROSC

    Moderate

    [7]

    cohort

    (17,887/4363)

    4. Survival to

    admission

    Cady et al. [50]

    Retrospective

    5822

    All causes

    Combitube

    N/A

    5. Survival to

    discharge

    6. Neurological outcome

    1. ROSC

    Serious

    cohort

    (4335/1437)

    2. Survival to

    admission

    3. Survival to

    Chiang et al. [51]

    Retrospective

    4640

    Non-traumatic

    Not specified

    Utstein style registry, Taipei (2008-2013)

    discharge

    3. ROSC

    Serious

    Davey & Dicker

    cohort

    Retrospective

    (1541/3099)

    965 (293/672)

    All causes

    Not specified

    St John New Zealand OHCA (2013-2015)

    Survival to

    admission

    Survival to discharge
  • Neurological outcome
  • 1. ROSC

    Serious

    [52] cohort

    Do Shin et al. [53] Retrospective

    641 (250/391)

    Presumed cardiogenic aetiology

    Not specified

    Korea nationwide OHCA cohort database (2006-2008)

    2. Survived to

    admission

    3. Survival to discharge

    1. Survival to

    Moderate

    cohort

    admission

    2. Survival to

    discharge

    Evans et al. [54]

    Erath et al. [71]

    Retrospective

    cohort

    Propensity matched

    1555 (1282/273)

    208 (160/48)

    Traumatic

    All causes

    Not specified

    Laryngeal tube

    Resuscitation outcomes

    Consortium epistry-trauma and prospective observational prehospital and hospital registry (2005-2007 & 2010-2011)

    N/A

    1. Survival to

    discharge

    1. Survival to

    Serious

    Moderate

    cohort

    admission

    2. Survival to

    Fukuda et al. [6]

    Retrospective

    132,874

    All causes

    Not specified

    All Japan Utstein Registry (2005-2014)

    discharge

    3. Survival to

    Moderate

    cohort

    (22,806/110,068)

    discharge

    (continued on next page)

    Table 1 (continued)

    2302

    L. White et al. / American Journal of Emergency Medicine 36 (2018) 22982306

    Study

    Study design

    Sample (ETT/SGA)

    Cause of OOHCA

    SGA employed

    Registry utilized (year)

    Outcomes

    Risk of bias?

    Hanif et al. [55]

    Retrospective

    1158 (1027/131)

    All causes

    Combitube or

    N/A

    4. Neurological outcome

    1. ROSC

    Moderate

    cohort

    oesophageal obturator

    2. Survival to admission

    3. Survival to

    discharge

    Hasegawa &

    Retrospective

    281,522

    All causes

    Not specified

    All-Japan Utstein Registry (2005-2014)

    1. ROSC

    Serious

    Takei [56]

    Jarman et al. [57]

    cohort

    Prospective

    (41,972/239,550)

    316 (273/43)

    All causes

    King LT

    N/A

    2. Survival to discharge

    3. Neurological outcome

    1. ROSC

    Moderate

    Kajino et al. [58]

    observational

    Retrospective

    5377

    Non-traumatic

    Not specified

    Utstein style registry, Osaka (2005-2008)

    1. ROSC

    Serious

    Kang et al. 2015

    cohort

    Retrospective

    (1679/3698)

    2829

    Non-traumatic

    Not specified

    Korea nationwide OHCA cohort database (2010-2013)

    Survival to admission
  • Survival to discharge
  • Neurological outcome
  • ROSC
  • Serious

    [59]

    cohort

    (1634/1195)

    2. Survival to

    Lin et al. [60]

    Retrospective

    1428 (1384/44)

    All causes

    Not specified

    Taiwan EMS and hospital registries

    discharge

    3. Neurological outcome

    1. ROSC

    Serious

    cohort

    2. Survival to admission

    3. Survival to

    McMullan et al.

    Retrospective

    8701

    All causes

    Not specified

    CARES Registry (2011)

    discharge

    1. ROSC

    Moderate

    [61]

    cohort

    (5591/3110)

    Survival to admission
  • Survival to discharge
  • Neurological
  • outcome

    Mulder et al. [62]

    RCT

    188 (101/87)

    Non-traumatic

    LMA

    N/A

    ROSC

    Low

    Nagao et al. [31]

    Retrospective

    199 (10/189)

    All causes

    LMA and combitube

    Utstein style registry, Tokyo (2006-2007)

    ROSC

    Serious

    Noda et al. [63]

    cohort

    Retrospective

    28 (4/24)

    Cardiogenic aetiology

    LMA and combitube

    Utstein style registry, Kyushu University Hospital (2000-2006)

    ROSC

    Serious

    cohort

    Survival to admission
  • Survival to
  • discharge

    Rabitsch et al.

    RCT

    172 (83/89)

    Non-traumatic

    Combitube

    N/A

    4. Neurological outcome

    1. ROSC

    Low

    [64]

    2. Survival to admission

    3. Survival to

    discharge

    Sulzgruber et al. [65]

    Propensity matched analysis

    420 (210/210)

    All causes

    Not specified

    N/A

    1. Survival to discharge

    Moderate

    L. White et al. / American Journal of Emergency Medicine 36 (2018) 22982306 2303

    * Randomised controlled trials (RCTs) were assessed for risk of bias and methodological quality using the Cochrane Collaboration’s tool for assessing the risk of bias [9]. Non-randomised were assessed using the ROBINS-I tool [10]. ROSC = return of spontaneous circulation; OHCA = out-of-hospital cardiac arrest; ETT = endotracheal tube; SGA = supraglottic airway; LMA = laryngeal mask airway; LT = Laryngeal Tube.

    but not survival to discharge or neurological state with ETT insertion remained. This sensitivity analysis still had significant limitations such as, difference in seniority and skill level of EMT, indication and airway difficulty. All of these factors directly impact on the success of the airway techniques, as well as, the expertise of the provider managing the car- diac arrest as a whole [73]. Furthermore, the majority of studies did not report on intervention crossover rates, which would adversely affect time to successful ventilation, as well as delays to chest compressions and other interventions. A further limitation to the overall results in- clude large amount of overlapping data from the same databases. When studies were assessed for duplication, eight overlapping studies were identified. On sensitivity analysis, duplicate databases were re- moved which resulted in no change the significance of the overall re- sults, or the heterogeneity of the overall results.

    2. Neurological outcome

    ROSC
  • Survival to discharge
  • Neurological outcome
  • ROSC
  • Survival to discharge
  • Neurological outcome
  • Neurological outcome
  • Survival to admission
  • Survival to discharge
  • Neurological outcome
  • ROSC
  • Neurological outcome
  • ROSC
  • Survival to discharge
  • Serious

    Serious

    Serious

    Low

    Serious

    Serious

    Recommendations based on prior meta-analyses have been largely limited by the quality of included studies. For the first time, the present study performed a sensitivity analysis based on low risk of bias RCTs. The sensitivity analyses showed no difference between ETT and SGA in regard to ROSC (OR = 0.90; 95%CI = 0.65 to 1.25; I2 = 12%; p =

    Utstein style registry, Ishikawa (2004-2008)

    Modified Upstein style registry, Saitama (2006-2007)

    0.59), survival to admission (OR = 1.00; 95%CI = 0.68 to 1.47; I2 = 0%; p = 0.99), survival to discharge (OR = 0.90; 95%CI = 0.68 to 1.20; I2 = 70%; p = 0.49) or neurological recovery at discharge (OR = 0.88; 95%CI = 0.57 to 1.35; I2 = 84%; p = 0.55). All five studies were rel- atively homogenous utilizing non-physician providers for the manage- ment of non-Traumatic cardiac arrest. Three [52,63] of the five studies compared ETT to LMA, whereas the studies by Wang et al. and Rabitsch et alcompared ETT to esophagotracheal combitube (ETC). Between the studies, the first attempt success rate for LMA (Supreme and I-gel) in- sertion was reasonably consistent (75-79%). There was a higher than expected First attempt success rate for ETC 98% and wide variation in ETT first attempt success rate (51-96%). Each of these studies appears to have controlled for intra and post resuscitation care by following na- tional guidelines. However, adherence to these guidelines is not commented on. Notably, none of these studies included patients receiv- ing automated chest compressions. Therefore, these five RCTs serve as the first level 1 recommendation to show no difference in survival or neurological outcome between ETT and SGA in advanced airway man- agement for OHCA.

    Not specified

    LMA and combitube

    All-Japan Utstein Registry (2005-2007)

    King laryngeal tube, LMA and combitube Laryngeal tube

    ROC PRIMED Trial

    N/A

    Not specified

    Marshall LMA

    (2008-2011)

    Further sensitivity analyses were performed in an attempt to control for specific intra-arrest management variables. These included analyses of SGA device type and type of chest compression. Interestingly, the only management related sensitivity analysis to show a significant ben- efit without heterogeneity was in the presence of concurrent automated chest compressions. This is important given the increasing popularity of automated compression devices for both in and out of hospital cardiac arrest [7,14]. This subgroup analysis was only able to be performed on short term outcomes (ROSC and survival to admission).

    All causes (cardiac and non-cardiac subgroups)

    Non-traumatic

    Non-traumatic

    Non-traumatic

    All causes (traumatic and non-traumatic subgroups)

    All causes

    Analyses of intrathoracic pressure during both manual and auto- mated chest compressions have previously been performed [74]. These show that there a greater sustained pressure throughout the chest compression cycle with mechanical compressions [75]. However, compression induced ventilation is not possible in humans. Therefore, a patent airway and assisted ventilation is still required during cardiopul- monary resuscitation. The benefit of ETT over SGA in this setting is likely related to elevated intrathoracic pressure and thus reduced efficacy of SGAs. These findings suggest that if an emergency response service uti- lizes automated compression devices, Endotracheal tubes are likely to result in increased survival. The one caveat to this suggestion is that when mechanical compressions are used, the placement of an ETT will be more difficult. For this reason, airway adjuncts such as the digitally- assisted pre-loaded bougie technique should be used [76,77].

    Takei et al. [66]

    Prospective observational

    948 (268/680)

    Tanebe et al. [67]

    Retrospective cohort

    42,632 (12,992/29,640)

    Wang et al. [68]

    Secondary analysis of RCT data

    RCT

    10,425 (8487/1968) 3000 (1495/1505)

    Wang et al. [73]

    Yanagawa & Sakamoto [47]

    Retrospective

    636 (158/478)

    Yeung et al. [69]

    Prospective observational

    75 (50/25)

    Airway management is only one facet of intra and post cardiopulmo- nary resuscitation care. For this reason, it is understandable why any dif- ference in outcome will diminish over time. The results of the present study showed no significant increase in survival to discharge or neuro- logical outcome, with significant heterogeneity on all subgroup

    2304 L. White et al. / American Journal of Emergency Medicine 36 (2018) 22982306

    Table 2

    Association between Endotracheal tube intubation versus Supraglottic airway for return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation.

    Group Events/total no of patients Risk difference, % (95%CI) Relative odds I2%

    ETT

    SGA

    Odds ratio (95%CI)

    p value

    All studies [6,7,12,31,47,49-53,55-59,61-70,72]

    18,877/95,314

    20,942/301,844

    0.05 (0.03 to 0.06)

    1.44 (1.27 to 1.63)

    b0.00001

    91

    Analysis after duplicate database removal [6,7,14,49-57,59-66,68,69,70,72]

    17,201/80471

    17,835/263513

    0.05 (0.03 to 0.08)

    1.36 (1.20 to 1.54)

    b0.00001

    89

    EMT provider [7,14,31,47,50-52,55-67, 69,70,72]

    18,847/95,149

    20,925/301,713

    0.05 (0.03 to 0.07)

    1.44 (1.28 to 1.63)

    b0.00001

    92

    Manual chest compressions [7,47,49,50-52,55-67,69,70,72]

    18,144/93,604

    20,842/301,525

    0.05 (0.03 to 0.06)

    1.43 (1.26 to 1.62)

    b0.00001

    92

    Automated chest compressions [7,14]

    733/1710

    100/319

    0.10 (0.05 to 0.16)

    1.55 (1.20 to 2.00)

    0.0009

    0

    Laryngeal mask airway [49,51,52,62,69,70]

    1046/6627

    1452/10,526

    0.06 (0.00 to 0.12)

    1.43 (1.04 to 1.97)

    0.03

    86

    Laryngeal tube [49,50,55,57,64,65,72]

    2272/6936

    1061/3570

    0.04 (0.00 to 0.08)

    1.11 (0.88 to 1.40)

    0.40

    70

    Low risk [14,62,64,70,72]

    774/6277

    922/6940

    -0.02 (-0.08 to 0.04)

    0.92 (0.80 to 1.05)

    0.22

    23

    Moderate risk [7,55,56,61,65]

    10,531/24419

    2414/8020

    0.10 (0.07 to 0.13)

    1.58 (1.43 to 1.74)

    b0.00001

    45

    Serious risk [47,49,50-53,58,59,66,67,51-53,56,58,59,66,67,69]

    7572/64,618

    17,606/286,884

    0.04 (0.03 to 0.05)

    1.70 (1.42 to 2.02)

    b0.00001

    91

    Table 3

    Association between endotracheal tube intubation versus supraglottic airway (SGA) for survival to admission following cardiopulmonary resuscitation.

    Group Events/total no of patients Risk difference, % (95%CI) Relative odds I2%

    ETT

    SGA

    Odds ratio (95%CI)

    p value

    All studies [7,14,49,50,52,53,55,58-61,64,70,71]

    11,730/33,561

    5235/18,195

    0.05 (0.02 to 0.09)

    1.36 (1.12 to 1.66)

    0.002

    91

    Analysis after duplicate database removal

    11,040/31878

    3819/14473

    0.05 (0.02 to 0.10)

    1.38 (1.10 to 1.72)

    0.005

    92

    [7,14,49,50,52,53,55,58,61,63,64,70,71]

    EMT provider [7,49,50,52,53,55,58,61,63,64,70,71]

    11,657/33,234

    5206/18,016

    0.06 (0.02 to 0.10)

    1.41 (1.14 to 1.74)

    0.0001

    93

    Manual chest compressions [7,49,50,52,53,55,58,59,60,61,63,64,70,71]

    11,254/31,849

    5190/17,876

    0.05 (0.01 to 0.09)

    1.30 (1.06 to 1.61)

    0.01

    92

    Automated chest compressions [7,14]

    476/1712

    45/319

    0.08 (-0.04 to 0.20)

    2.16 (1.54 to 3.02)

    b0.00001

    0

    Laryngeal mask airway [14,52,53,60,70]

    1078/2711

    1580/5103

    0.04 (-0.02 to 0.10)

    1.23 (0.88 to 1.73)

    0.23

    81

    Laryngeal tube [49,50,55,64]

    1346/5733

    646/3181

    0.03 (-0.03 to 0.08)

    1.26 (0.82 to 1.93)

    0.29

    54

    Low risk [14,64,70]

    910/2207

    1122/2745

    -0.01 (-0.03 to 0.02)

    0.97 (0.86 to 1.09)

    0.59

    0%

    Moderate risk [7,31,55,57,66,71]

    8895/24915

    1932/8143

    0.09 (0.04 to 0.14)

    1.61 (1.24 to 2.09)

    0.0003

    89

    Serious risk [49,50,52,58,60,64]

    1925/6439

    2181/7307

    0.05 (0.00 to 0.09)

    1.30 (1.01 to 1.68)

    0.04

    75

    analyses. This only serves to illustrate the complexity of post arrest neu- rological outcomes, beyond simply avoiding hypoxia. Even in the most well designed RCT it would be difficult to control for key intra arrest var- iables (e.g. cause of arrest [78], antiarrhythmic used [79]) or post arrest care (e.g. cooling [80], blood pressure management [73]).

    Limitations

    The predominant limitation to this review is the lack of RCTs and a significant number of retrospective studies from overlapping databases. On the subgroup analysis removing the overlapping studies, this did not affect any of the results. This inconsistency of reported outcomes has been highlighted in Critical care literature remains a significant limita- tion to the conclusions drawn from the present study. Furthermore, the five RCTs utilized different Supraglottic airways, which may impact the overall outcome.

    The diminishing effect of the overall result on longer term outcomes such as neurological status on discharge likely reflects the multifactorial nature of arrest cause, provider type and management strategy. The ma- jority of studies included in the present review do not control for or even mention many variables such as antiarrhythmic used and post ROSC management. This has a significant bearing on the conclusions drawn from the longer term outcomes included in the present study.

    Conclusion

    The present study showed a significant benefit with use of endotra- cheal intubation over supraglottic airway, however this is likely the re- sult of numerous other factors related to the cause and management of cardiac arrest. Five low risk studies provide a generalised level one rec- ommendation that overall there is no benefit for endotracheal intuba- tion over supraglottic airway devices. In the situation of automated

    Table 4

    Association between endotracheal tube (ETT) intubation versus supraglottic airway (SGA) for survival to discharge following cardiopulmonary resuscitation.

    Group

    Events/total no

    of patients

    Risk difference, % (95%CI)

    Relative odds

    I2%

    ETT

    SGA

    Odds ratio (95%CI)

    p value

    All studies [6,7,14,47,50-58,60,61,63,65-68,70-72]

    7826/120,274

    13,898/320,290

    0.01 (0.00 to 0.02)

    1.28 (1.02 to 1.60)

    0.03

    96

    Analysis after duplicate database removal [6,7,47,50-58,60,61,63,65,70-72]

    7171/105599

    12,474/286928

    0.01 (0.00 to 0.03)

    1.33 (1.02 to 1.72)

    0.03

    97

    EMT provider [6,7,14,47,50-56,58,60,61,63,65-67,70-72]

    7826/120,274

    13,898/320,290

    0.01 (0.00 to 0.02)

    1.28 (1.02 to 1.60)

    0.03

    96

    Manual chest compressions [6,7,14,47,50-56,58,60,61,63,65-67,70-72]

    7712/118646

    13,882/320013

    0.01 (0.00 to 0.02)

    1.28 (1.02 to 1.61)

    0.04

    96

    Automated chest compressions

    N/A

    N/A

    N/A

    N/A

    N/A

    N/A

    Laryngeal mask airway [14,51-53,60,69,70]

    595/6794

    682/10859

    0.03 (0.01 to 0.06)

    1.80 (1.14 to 2.83)

    0.01

    85

    Laryngeal tube [50,55,65,72]

    528/7810

    564/3574

    -0.02 (-0.14 to 0.09)

    0.96 (0.32 to 2.90)

    0.94

    97

    Low risk [70,72]

    512/6111

    593/6792

    -0.01 (-0.03 to 0.02)

    0.90 (0.68 to 1.20)

    0.49

    70

    Moderate risk [6,7,53,55,61,65,71]

    4243/48513

    1917/31352

    0.03 (0.01 to 0.05)

    1.54 (1.11 to 2.15)

    0.01

    92

    Serious risk [50-52,54,56,58,60,63,66,67,69]

    3071/65,650

    11,388/282,146

    0.00 (-0.01 to 0.02)

    1.34 (0.90 to 2.00)

    0.15

    97

    L. White et al. / American Journal of Emergency Medicine 36 (2018) 22982306 2305

    Table 5

    Association between endotracheal tube (ETT) intubation versus supraglottic airway (SGA) for survival to discharge with a neurologically intact state following cardiopulmonary resuscitation.

    Group Events/total no of patients Risk difference, % (95%CI) Relative odds I2%

    ETT

    SGA

    Odds ratio (95%CI)

    p value

    All studies [6,7,47,51,56,58,59,61,63,65,67,68,70,72]

    3853/121,006

    4579/317,255

    0.01 (0.00 to 0.01)

    1.16 (0.94 to 1.41)

    0.16

    91

    Analysis after duplicate database removal [6,7,51,56,59,61,65,68,70,72]

    3628/106173

    4130/283415

    0.01 (0.00 to 0.02)

    1.17 (0.92 to 1.49)

    0.20

    93

    EMT provider [6,7,47,51,56,58,59,61,63,64,67-69,70,72]

    3853/121,006

    4579/317,255

    0.01 (0.00 to 0.01)

    1.16 (0.94 to 1.41)

    0.16

    91

    Manual chest compressions [6,7,47,51,56,58,59,61,63,65,67,68,70,72]

    3773/119378

    4569/316,978

    0.01 (0.00 to 0.01)

    1.15 (0.93 to 1.41)

    0.20

    91

    Automated chest compressions

    N/A

    N/A

    N/A

    N/A

    N/A

    N/A

    Laryngeal mask airway [65,70]

    356/5948

    397/7981

    0.01 (0.00 to 0.01)

    1.13 (0.95 to 1.33)

    0.17

    13

    Laryngeal tube [68,72]

    162/2288

    131/1904

    0.01 (-0.06 to 0.08)

    1.14 (0.41 to 3.17)

    0.80

    93

    Low risk [70,72]

    375/5902

    418/6382

    -0.01 (-0.03 to 0.02)

    0.88 (0.57 to 1.35)

    0.55

    84

    Moderate risk [6,7,61,66,71]

    2313/47,076

    744/30,782

    0.02 (-0.01 to 0.05)

    1.46 (0.88 to 2.42)

    0.15

    96

    Serious risk [47,51,54,58,59,63,67,68]

    1165/68,028

    3417/280,091

    0.00 (0.00 to 0.00)

    1.06 (0.92 to 1.22)

    0.41

    51

    chest compressions endotracheal intubation will likely result in an early survival benefit.

    Conflict of interest

    The authors have no conflicts of interest to declare.

    Appendix A. Supplementary data

    Supplementary data to this article can be found online at https://doi. org/10.1016/j.ajem.2018.09.045.

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