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Does Advanced Airway Management Improve Outcomes in Adult Out-of-Hospital Cardiac Arrest?
ANNALS OF EMERGENCY MEDICINE
-
2013
Systematic Review Snapshot TAKE-HOME MESSAGE Advanced airway management in adult out-of-hospital cardiac arrest lacks clear benefit, but available studies are unable to control for many confounders in this population. METHODS DATA SOURCES After searching MEDLINE, EMBASE, and the Cochrane Library on February 1, 2013, the authors also reviewed references of relevant articles and contacted experts in the field for additional article recommendations. STUDY SELECTION Observational and experimental studies including both basic (bagvalve-mask ventilation, head-tiltchin-lift, mouth-to-mouth ventilation, nasopharyngeal airways, and oropharyngeal airways) airway interventions and advanced (intubation, supraglottic airways, and surgical airways) airway interventions in adult out-ofhospital cardiac arrest victims. DATA EXTRACTION AND SYNTHESIS Two investigators independently assessed each study for methodological quality and risk of bias, and then abstracted relevant data. The authors calculated pooled odds ratio for basic versus advanced airway interventions, and predefined subgroup analyses according to advanced airway type (eg, supraglottic airway versus intubation). The authors divided
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2013
Does Advanced Airway Management Improve Outcomes in Adult Out-of-Hospital Cardiac Arrest? EBEM Commentators
Jestin N. Carlson, MD, MS Department of Emergency Medicine Saint Vincent Hospital Erie PA Department of Emergency Medicine University of Pittsburgh School of Medicine Pittsburgh PA
Joshua C. Reynolds, MD, MS Department of Emergency Medicine Michigan State University College of Human Medicine Grand Rapids MI
Results Selected results of pooled data (n£388,878).* Survival
Odds Ratio (95% Confidence Interval) Heterogeneity (I2), %
Any advanced airway intervention Short-term Longer-term Intubation Short-term Longer-term Supraglottic airway Short-term Longer-term
0.84 (0.62–1.13) 0.49 (0.37–0.65)
92 76
0.79 (0.54–1.16) 0.48 (0.36–0.64)
93 77
0.56 (0.40–0.78) 0.35 (0.28–0.44)
89 56
*Reference category is basic airway interventions. Short-term survival is defined as a return of spontaneous circulation or survival to hospital admission. Longer-term survival is defined as survival to hospital discharge or 1month follow-up.
The authors identified 799 potential studies, of which 17 met inclusion criteria: 12 retrospective cohort studies, 3 prospective cohort studies, and 2 trials with historical controls. There were no randomized controlled trials comparing advanced and basic airway interventions in adult out-of-
hospital cardiac arrest. The total number of subjects across all studies was 388,878. Advanced airway interventions were associated with lower odds of longer-term survival (Table) but did not affect short-term survival. When analyzed by advanced airway type, both intubation and
Annals of Emergency Medicine 1
Systematic Review Snapshot
survival into 2 categories: shortterm survival (return of spontaneous circulation or survival to hospital admission) and longerterm survival (survival to hospital discharge or survival at 1 month).
supraglottic airways were associated with lower odds of short- and longerterm survival compared with basic airway interventions. The authors noted substantial statistical heterogeneity (I2 >50% for each outcome) and clinical heterogeneity with the identified studies. The studies were selected from various geographic regions spanning 24 years, with various sample sizes and mixed causes (traumatic and nontraumatic) of cardiac arrest. A third of included studies did not adjust, match, or balance for any confounding variable. No study adjusted for interruptions in chest compressions, delays to defibrillation, hyperventilation, or cardiopulmonary resuscitation quality. The poor results for longer-term survival were robust to sensitivity analyses of nontraumatic cause of cardiac arrest and attempted airway placement.
Commentary The effectiveness of advanced airway management is an area of ongoing controversy. Although the Fouche meta-analysis provides a synthesis of the existing literature on this topic, all of the included observational studies
2 Annals of Emergency Medicine
are affected by confounding by indication. Another important limitation is the relative paucity of data from prospective clinical trials.
Airways in out-of-hospital cardiac arrest: systematic review and meta-analysis. Prehosp Emerg Care; http://dx.doi.org/10. 3109/10903127.2013.831509.
The highest-quality studies in this analysis, which account for the majority of pooled patients, were conducted within the last 3 years in eastern Asia and may not be generalizable to the United States.1-4 This systematic review and meta-analysis is also limited by the lack of adjustment for prognostic variables. The authors attempted to overcome this by using a model that favorably weights studies of better quality; however, the authors acknowledge that their results may be biased. Despite its shortcomings, this systematic review and meta-analysis represents the best available synthesis of evidence to date on the optimal airway management of adult victims of out-of-hospital cardiac arrest.
1. Chien LC, Hsu HC, Lin CH, et al. Use of an intubating laryngeal mask airway on out-ofhospital cardiac arrest patients in a developing emergency medical service system. J Formos Med Assoc. 2012;111:24-29. 2. Nagao T, Kinoshita K, Sakurai A, et al. Effects of bag-mask versus advanced airway ventilation for patients undergoing prolonged cardiopulmonary resuscitation in prehospital setting. J Emerg Med. 2012;42:162-170. 3. Takei Y, Enami M, Yachida T, et al. Tracheal intubation by paramedics under limited indication criteria may improve the shortterm outcome of out-of-hospital cardiac arrests with noncardiac origin. J Anesth. 2010;24:716-725. 4. Shin SD, Ahn KO, Song KJ, et al. Out-ofhospital airway management and cardiac arrest outcomes: a propensity score matched analysis. Resuscitation. 2012;83:313-319. 5. Gausche M, Lewis RJ, Stratton SJ, et al. Effect of out-of-hospital pediatric endotracheal intubation on survival and neurological outcome: a controlled clinical trial. JAMA. 2000;283:783-790. 6. Wang HE, Bogucki S. Out-of-hospital endotracheal intubation: are observational data useful? Acad Emerg Med. 2010;17:987-988. 7. Benger JR, Voss S, Coates D, et al. Randomised comparison of the effectiveness of the laryngeal mask airway supreme, i-gel and current practice in the initial airway management of prehospital cardiac arrest (REVIVE-Airways): a feasibility study research protocol. BMJ Open. 2013; http://dx.doi.org/ 10.1136/bmjopen-2012-002467.
The sole randomized controlled trial of intubation in out-of-hospital cardiac arrest focused on children.5 Fouche et al call for a rigorous prospective trial to determine the ideal airway management strategy in adult out-ofhospital cardiac arrest, but there are clear challenges to attempting such a study.6 An ongoing clinical investigation in the United Kingdom may help to provide important answers.7 Editor’s Note: This is a clinical synopsis, a regular feature of the Annals’ Systematic Review Snapshot (SRS) series. The source for this systematic review snapshot is: Fouche PF, Simpson PM, Bendall J, et al.
Michael Brown, MD, MSc, Alan Jones, MD, and David Newman, MD, serve as editors of the SRS series.
Volume
-,
no.
-
:
-
2013
-
2013
Systematic Review Snapshot TAKE-HOME MESSAGE Advanced airway management in adult out-of-hospital cardiac arrest lacks clear benefit, but available studies are unable to control for many confounders in this population. METHODS DATA SOURCES After searching MEDLINE, EMBASE, and the Cochrane Library on February 1, 2013, the authors also reviewed references of relevant articles and contacted experts in the field for additional article recommendations. STUDY SELECTION Observational and experimental studies including both basic (bagvalve-mask ventilation, head-tiltchin-lift, mouth-to-mouth ventilation, nasopharyngeal airways, and oropharyngeal airways) airway interventions and advanced (intubation, supraglottic airways, and surgical airways) airway interventions in adult out-ofhospital cardiac arrest victims. DATA EXTRACTION AND SYNTHESIS Two investigators independently assessed each study for methodological quality and risk of bias, and then abstracted relevant data. The authors calculated pooled odds ratio for basic versus advanced airway interventions, and predefined subgroup analyses according to advanced airway type (eg, supraglottic airway versus intubation). The authors divided
Volume
-,
no.
-
:
-
2013
Does Advanced Airway Management Improve Outcomes in Adult Out-of-Hospital Cardiac Arrest? EBEM Commentators
Jestin N. Carlson, MD, MS Department of Emergency Medicine Saint Vincent Hospital Erie PA Department of Emergency Medicine University of Pittsburgh School of Medicine Pittsburgh PA
Joshua C. Reynolds, MD, MS Department of Emergency Medicine Michigan State University College of Human Medicine Grand Rapids MI
Results Selected results of pooled data (n£388,878).* Survival
Odds Ratio (95% Confidence Interval) Heterogeneity (I2), %
Any advanced airway intervention Short-term Longer-term Intubation Short-term Longer-term Supraglottic airway Short-term Longer-term
0.84 (0.62–1.13) 0.49 (0.37–0.65)
92 76
0.79 (0.54–1.16) 0.48 (0.36–0.64)
93 77
0.56 (0.40–0.78) 0.35 (0.28–0.44)
89 56
*Reference category is basic airway interventions. Short-term survival is defined as a return of spontaneous circulation or survival to hospital admission. Longer-term survival is defined as survival to hospital discharge or 1month follow-up.
The authors identified 799 potential studies, of which 17 met inclusion criteria: 12 retrospective cohort studies, 3 prospective cohort studies, and 2 trials with historical controls. There were no randomized controlled trials comparing advanced and basic airway interventions in adult out-of-
hospital cardiac arrest. The total number of subjects across all studies was 388,878. Advanced airway interventions were associated with lower odds of longer-term survival (Table) but did not affect short-term survival. When analyzed by advanced airway type, both intubation and
Annals of Emergency Medicine 1
Systematic Review Snapshot
survival into 2 categories: shortterm survival (return of spontaneous circulation or survival to hospital admission) and longerterm survival (survival to hospital discharge or survival at 1 month).
supraglottic airways were associated with lower odds of short- and longerterm survival compared with basic airway interventions. The authors noted substantial statistical heterogeneity (I2 >50% for each outcome) and clinical heterogeneity with the identified studies. The studies were selected from various geographic regions spanning 24 years, with various sample sizes and mixed causes (traumatic and nontraumatic) of cardiac arrest. A third of included studies did not adjust, match, or balance for any confounding variable. No study adjusted for interruptions in chest compressions, delays to defibrillation, hyperventilation, or cardiopulmonary resuscitation quality. The poor results for longer-term survival were robust to sensitivity analyses of nontraumatic cause of cardiac arrest and attempted airway placement.
Commentary The effectiveness of advanced airway management is an area of ongoing controversy. Although the Fouche meta-analysis provides a synthesis of the existing literature on this topic, all of the included observational studies
2 Annals of Emergency Medicine
are affected by confounding by indication. Another important limitation is the relative paucity of data from prospective clinical trials.
Airways in out-of-hospital cardiac arrest: systematic review and meta-analysis. Prehosp Emerg Care; http://dx.doi.org/10. 3109/10903127.2013.831509.
The highest-quality studies in this analysis, which account for the majority of pooled patients, were conducted within the last 3 years in eastern Asia and may not be generalizable to the United States.1-4 This systematic review and meta-analysis is also limited by the lack of adjustment for prognostic variables. The authors attempted to overcome this by using a model that favorably weights studies of better quality; however, the authors acknowledge that their results may be biased. Despite its shortcomings, this systematic review and meta-analysis represents the best available synthesis of evidence to date on the optimal airway management of adult victims of out-of-hospital cardiac arrest.
1. Chien LC, Hsu HC, Lin CH, et al. Use of an intubating laryngeal mask airway on out-ofhospital cardiac arrest patients in a developing emergency medical service system. J Formos Med Assoc. 2012;111:24-29. 2. Nagao T, Kinoshita K, Sakurai A, et al. Effects of bag-mask versus advanced airway ventilation for patients undergoing prolonged cardiopulmonary resuscitation in prehospital setting. J Emerg Med. 2012;42:162-170. 3. Takei Y, Enami M, Yachida T, et al. Tracheal intubation by paramedics under limited indication criteria may improve the shortterm outcome of out-of-hospital cardiac arrests with noncardiac origin. J Anesth. 2010;24:716-725. 4. Shin SD, Ahn KO, Song KJ, et al. Out-ofhospital airway management and cardiac arrest outcomes: a propensity score matched analysis. Resuscitation. 2012;83:313-319. 5. Gausche M, Lewis RJ, Stratton SJ, et al. Effect of out-of-hospital pediatric endotracheal intubation on survival and neurological outcome: a controlled clinical trial. JAMA. 2000;283:783-790. 6. Wang HE, Bogucki S. Out-of-hospital endotracheal intubation: are observational data useful? Acad Emerg Med. 2010;17:987-988. 7. Benger JR, Voss S, Coates D, et al. Randomised comparison of the effectiveness of the laryngeal mask airway supreme, i-gel and current practice in the initial airway management of prehospital cardiac arrest (REVIVE-Airways): a feasibility study research protocol. BMJ Open. 2013; http://dx.doi.org/ 10.1136/bmjopen-2012-002467.
The sole randomized controlled trial of intubation in out-of-hospital cardiac arrest focused on children.5 Fouche et al call for a rigorous prospective trial to determine the ideal airway management strategy in adult out-ofhospital cardiac arrest, but there are clear challenges to attempting such a study.6 An ongoing clinical investigation in the United Kingdom may help to provide important answers.7 Editor’s Note: This is a clinical synopsis, a regular feature of the Annals’ Systematic Review Snapshot (SRS) series. The source for this systematic review snapshot is: Fouche PF, Simpson PM, Bendall J, et al.
Michael Brown, MD, MSc, Alan Jones, MD, and David Newman, MD, serve as editors of the SRS series.
Volume
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no.
-
:
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2013