Article, Intubation, Resuscitation, Traumatology

Prehospital endotracheal intubation and survival after out-of-hospital cardiac arrest: results from the Korean nationwide registry

a b s t r a c t

Purpose: Optimal out-of-hospital cardiac arrest (OHCA) airway management strategies are still controversial. Re- cent studies reported survival was higher among patients who received bag-valve-mask (BVM) than those re- ceiving Endotracheal intubation or Supraglottic airway . The aim of this study was to compare neurologically favorable survival outcomes among adult nontraumatic OHCA patients by prehospital airway.

Methods: We used the Korean nationwide OHCA cohort database from 2010 to 2013. The inclusion criteria were all OHCA adults with presumed cardiac etiology, resuscitated by level-1 emergency medical technician. Patients were ex- cluded if their information about the method of prehospital airway or clinical outcomes at hospital discharge could not be captured. The primary outcome was neurologically favorable survival to discharge. We compared the outcomes among 3 groups (ETI, SGA, or BVM) by prehospital airway using multivariable logistic regression with interaction model. Results: Of 98896 patients with OHCA, 32513 were included in analysis. Patients receiving BVM were 29684 and 2829 underwent advanced airway management including 1634 with SGA and 1195 with ETI. The odds of neuro- logically favorable survival to discharge was significantly higher in the ETI group compared to the BVM group (adjusted OR, 1.405; 95% CI, 1.1001-1.971). In the interaction model by witnessed status, the effect of ETI on good clinical outcomes was shown only in the patients whose arrest was unwitnessed.

Conclusion: In this Korean nationwide, population-based OHCA cohort, neurologically favorable survival to hos- pital discharge rates was significantly higher among patients who received ETI than those receiving BVM or SGA.

(C) 2015

Introduction

Endotracheal intubation has long been considered the optimal method for airway management during cardiopulmonary resuscitation (CPR). Although some studies have reported that out-of-hospital cardiac ar- rest (OHCA) patients who receive ETI have a significantly higher chance of surviving to hospital admission than those who do not [1,2], recent large- scale studies have reported that both ETI and supraglottic airway (SGA) in- sertion are associated with a reduced probability of neurologically favorable survival compared with conventional Bag-mask ventilation (BVM) [3-6].

Despite this evidence, the optimal prehospital airway strategy for OHCA patients is still under debate. Few data exist in support of the

? Funding: The project analyzed in this study was funded by the Korea Centers for Dis- ease Control and Prevention from 2010 to 2013 (2010-E33022-00, 2011-E33004-00, 2012- E33010-00, 2013-E33015-00).

?? Conflict of Interest: There are no conflicts of interest for all authors in this study.

* Corresponding author at: 166 Gumi-ro Bundang-gu, Seongnam 463-707, Republic of Korea. Tel.: +82 10 9342 5237.

E-mail addresses: [email protected] (K. Kang), [email protected] (T. Kim), [email protected] (Y.S. Ro), [email protected] (Y.J. Kim), [email protected]

(K.J. Song), [email protected] (S.D. Shin).

routine use of any specific approach to airway management during cardi- ac arrest. The optimal technique is dependent on the competence of the rescuer, the precise circumstances of the cardiac arrest, the patient’s con- dition, and the characteristics of the emergency medical service (EMS) or health care system [7,8]. In the United States, ETI is the most common air- way intervention; however, most Asian countries have a single-tiered EMS system, and less than 10% of OHCA patients receive ETI by emergen- cy medical technicians (EMTs) in the prehospital setting [9,10].

The aim of this study was to compare neurologically favorable Survival outcomes among adult nontraumatic OHCA patients in the Korean nation- wide OHCA cohort database according to the prehospital airway manage- ment technique used (ETI, SGA, and BVM). In addition, we aimed to investigate whether an interactive effect of airway management technique on survival outcome was present among patients with or without a witness.

Methods

Study design

This study was a population-based, retrospective cohort study ap- proved by the institutional review board of the study hospital, and

http://dx.doi.org/10.1016/j.ajem.2015.09.036

0735-6757/(C) 2015

informed consent was waived. We conducted secondary analysis of the cardiovascular disease surveillance (CAVAS) database.

Data source

The CAVAS project began in 2006, and it was conducted by the Ministry of Health and Welfare in collaboration with the National Emergency Man- agement Agency (NEMA) and the Korean Centers for Disease Control and Prevention to improve the outcome of cardiovascular disease in Korea. The CAVAS database consists of 3 disease entities, including acute myocardial infarction, acute stroke, and a nationwide EMS-assessed OHCA cohort that was obtained from EMS run sheets for demographic and Utstein infor- mation. After acquiring this information for the OHCA cohort from the da- tabase, a hospital medical record review was performed to assess hospital resuscitation and postresuscitation care and clinical outcomes.

All patient information from EMS run sheets is inputted by EMTs im- mediately after the transport of OHCA patients, and it is stored in the NEMA electronic server. Hospital medical records are reviewed and cap- tured by experts from the Korean Centers for Disease Control and Pre- vention using a structured survey form. All of the items, including the definitions, inclusion and exclusion criteria, examples, and warnings, are defined in the medical record review guidelines and were developed by the project Quality management committee (QMC). The QMC is com- posed of emergency physicians, epidemiologists, statistical experts, car- diologists, and medical record review experts.

Study setting

The Korean EMS system is a single-tiered, government-based system operated by 16 provincial headquarters of the National Fire Department, covering a population of approximately 50 million. Ambulance person- nel cannot declare death at the scene or terminate CPR unless return of spontaneous circulation (ROSC) occurs. Thus, all patients with OHCA are transported to an emergency department (ED). EMTs in Korea are clas- sified into 2 levels: level-1 and level-2 EMTs (comparable to EMT- intermediate and EMT-basic in the United States, respectively). Provi- sion of prehospital advanced airway management and administration of limited medications, such as epinephrine or atropine, are only to be performed by level-1 EMTs under direct or indirect medical control.

According to the Emergency Medical Service Act, level-1 EMTs should have graduated from an EMT school (a 3- to 4-year curriculum) of a university or college and have passed a national certification exam- ination composed of written and skills tests. The curriculum of the EMT school for advanced airway management should include 6 courses and 147 hours of education, with lectures and skill laboratories. After pass- ing the national certification examination, certified level-1 EMTs can apply for the Fire Service Academy during recruitment.

The Fire Service Academy provides class or distance learning to all re- cruited EMTs. A life-saving technique course, including advanced airway management, is provided for EMTs’ skill enhancement by the national Fire Service Academy or the nineteen provincial academies. To maintain knowledge and skills, continuing medical education comprising a 4-hour didactic session every year and a 2-month comprehensive Clinical training course held at an ED every 4 years are mandatory. Level-1 EMTs must abide by the NEMA’s internal regulation, which states that 1 attempt should be performed within a single 30-second duration, and up to 2 total advanced airway management attempts can be made on the scene.

Ambulance crews are usually composed of 3 members (level-1 and level-2 EMTs and a first-responder) in most metropolitan provinces, whereas 2 members (a level-1 or level-2 EMT and a first-responder) are on board in some rural provinces. In Korea, all EDs are designated as level 1, 2, or 3 by the government, with the level designation being based on the human resources, intensive care units, instruments, and equipment available at each ED. Level-1 (n = 19) and level-2 (n = 110) EDs have more resources and better facilities for emergency care

and must be covered by emergency physicians 24 hours a day. All EDs are subject to annual evaluation by the government audit committee.

Study population

The data were extracted between January 2010 and December 2013. The inclusion criteria were all OHCA adults older than 18 years old with a presumed cardiac etiology who were resuscitated by a level-1 EMT. Patients were excluded if information about the method of prehospital airway man- agement or the clinical outcomes at discharge could not be obtained.

The etiology of cardiac arrest was identified by medical record re- views, and we excluded cases with a primary Noncardiac etiology. We assumed the primary cardiac etiology if there was no description of a definite noncardiac etiology, such as trauma (mainly motor vehicle ac- cidents and falls from height), exsanguination, drowning, poisoning, burns, asphyxia, or hanging, in the medical records.

Outcomes and variables

The primary outcome was neurologically favorable survival to hospi- tal discharge, defined a priori as a Glasgow-Pittsburgh cerebral perfor- mance category (CPC) of 1 or 2 [11], and the secondary outcome was survival to hospital discharge. The CPC score was determined by the medical record reviewers based on the discharge summary or docu- mentation in the medical records.

The main exposure variable was the airway management technique performed by EMTs, classified as ETI, SGA, or BVM. The selection of the air- way management technique was completely dependent on the preference of the level-1 EMT at the scene. We used the Utstein-defined co-variables, including gender, age, witnessed status, bystander CPR, initial electrocar- diogram rhythm, prehospital defibrillation, arrest location, elapsed time interval from call to ambulance arrival at the scene (EMS response time), elapsed time interval from arrival at the scene to departure (EMS on- scene time), elapsed time interval from departure to arrival at the ED (EMS transport time), and prehospital ROSC. In addition, we added the fol- lowing co-variables: the level of the ED (level 1-3) to adjust for ED perfor- mance and community urbanization (metropolitan or not) to adjust for geographical variations in community performance and resources.

Statistical analysis

We compared the patient demographics, arrest characteristics and EMS time intervals among those receiving ETI, SGA or BVM using the ?2 test, 1-way analysis of variance or the 1-way Kruskal-Wallis test, as appropriate.

Afterward, we compared the outcomes among the 3 groups accord- ing to the airway management methods used. Multivariable logistic re- gression analyses were conducted to estimate the effect sizes of the prehospital airway management techniques on survival to discharge and Good neurologic outcome and to calculate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) after adjusting for the poten- tial confounders (the 13 co-variables mentioned above).

Finally, we applied interaction terms for airway management tech- nique and witnessed status to the multivariable logistic regression model to estimate the effects of the airway management techniques ac- cording to the witnessed status on the primary and secondary outcomes. If an interactive effect was detected between an airway management technique and witnessed status, then the adjusted ORs for the airway management technique on the study outcomes differed between the pa- tients with or without a witness. All statistical analyses were performed using SAS-version 9.4 software (SAS institute Inc, Cary, NC, USA).

Results

During the study period, 98896 patients with OHCA were detected in the CAVAS OHCA database. We excluded 2475 children younger

Figure. Study population and airway management.

than 18 years, in addition to 63908 patients according to the exclusion criteria (23359, noncardiac cause; 16402, resuscitation not attempted by EMS; 16031, treated by a level-2 EMT; 8099, unknown airway man- agement technique; and 17, unknown CPC at discharge). Of the remain- ing 32513 patients, 29684 (91.3%) underwent BVM and 2829 (8.7%) underwent advanced airway management, including 1634 (5.0%) treat- ed with SGA and 1195 (3.7%) treated with ETI (Figure).

The demographic and arrest characteristics according to the airway management techniques used are summarized in Table 1. The overall survival to discharge and neurologically favorable survival to discharge

95% CI, 0.931-1.380, for survival to discharge; and adjusted OR, 1.110; 95% CI, 0.848-1.452, for neurologically favorable survival to discharge). In contrast, the likelihood of survival to discharge was significantly higher for the patients with an unwitnessed arrest in the ETI group compared with those in the BVM group (adjusted OR, 1.735; 95% CI, 1.291-2.332), and the neurologically favorable survival to discharge rate was also signif- icantly higher (adjusted OR, 1.954; 95% CI, 1.213-3.148). Furthermore,

Table 1

Characteristics of out-of-hospital cardiac arrest patients by airway management

rates were 6.1% and 2.8%, respectively, in this study population. A total of 108 (9.0%) patients in the ETI group were alive at discharge, in addi-

ETI

(n = 1195)

SGA

(n = 1634)

BVM

(n = 29684)

tion to 154 (9.4%) in the SGA group and 1722 (5.8%) in the BVM group.

The neurologically favorable survival-to-discharge rates were 4.4% in

Male, n (%)

Age, median (IQR), y

769 (64.4)

70 (56-79)

1116 (68.3)

68 (54-78)

18890 (63.6)

70 (57-79)

the ETI group, 5.0% in the SGA group, and 2.6% in the BVM group

Witnessed arrest, n (%)

643 (53.8)

845 (51.7)

13270 (44.7)

(Table 1). The co-variables associated with the primary and secondary outcomes are summarized in Table 2.

For the full cohort (n = 32513), the adjusted multivariable logistic regression model demonstrated a significantly higher likelihood of sur- vival to discharge in the ETI group compared with the referent BVM group (adjusted OR, 1.490; 95% CI, 1.178-1.885); however, the odds of survival to discharge for the SGA group were not statistically higher

Bystander CPR, n (%)

116 (9.7)

243 (14.9)

2349 (7.9)

AED shock, n (%)

193 (16.2)

316 (19.3)

2979 (10.0)

Initial rhythm, n (%)

Shockable 113 (9.5) 207 (12.7) 2024 (6.8)

PEA 102 (8.5) 170 (10.4) 1918 (6.5)

Asystole 980 (82.0) 1257 (76.9) 25742 (86.7)

Arrest location, n (%)

Public place 171 (14.3) 310 (19.0) 4038 (13.6)

Community urbanization, n (%)

than those for the BVM group (adjusted OR, 1.102; 95% CI, 0.900-

Metropolitan

509 (42.6)

1111 (68.0)

13572 (45.7)

1.348). Similarly, using the adjusted model, the odds of neurologically

favorable survival to discharge were significantly higher for the ETI

Ambulance response time,

median (IQR), min

7 (5-10)

6 (5-9)

6 (5-9)

group compared with the BVM group (adjusted OR, 1.405; 95% CI, 1.1001-1.971), but no statistical significance was detected between

on-scene time, median (IQR), min

10 (6-14)

9 (6-12)

7 (5-10)

Transport time, median (IQR), min

ED level, n (%)

8 (5-14)

7 (5-10)

6 (4-10)

the SGA group and the BVM group for this outcome (adjusted OR,

1

142 (11.9)

159 (9.7)

2483 (8.4)

1.088; 95% CI, 0.822-1.439) (Table 3).

2

365 (30.5)

564 (34.5)

9349 (31.5)

After adjusting for the other co-variables in the interaction model, the adjusted ORs of the study outcomes for the ETI group significantly differed

from those for the BVM group according to the witnessed status. Among

3

Clinical outcomes, n (%) Prehospital ROSC survival discharge

688 (57.6)

76 (6.4)

108 (9.0)

911 (55.8)

87 (5.3)

154 (9.4)

17852 (60.1)

920 (3.1)

1722 (5.8)

the patients whose arrest was witnessed, those who underwent ETI did

Discharge with good neurology

53 (4.4)

81 (5.0)

784 (2.6)

not have significantly higher odds compared with those who underwent BVM in terms of the clinical outcomes at discharge (adjusted OR, 1.133;

IQR, interquatile range, AED, automated external defibrillator; PEA, pulseless electrical activity.

Table 2

Covariables associated with primary and secondary outcomes

Table 3

Multivariable adjusted logistic regression model for clinical outcomes by airway management

Total

(n = 32513)

Survival to discharge (n = 1984)

Neurologically favorable survival to discharge

(n = 918)

Airway

ETI

1195

108 (9.0)

53 (4.4)

SGA

1634

154 (9.4)

81 (5.0)

BVM

Gender

29684

1722 (5.8)

784 (2.6)

Airway management Survival discharge

(n = 1984)

Discharge with good neurologic outcome (n = 918)

n

aOR

(95% CI)

n

aOR (95% CI)

ETI

108

1.490

(1.178-1.885)

53

1.405 (1.001-1.971)

SGA

154

1.102

(0.900-1.348)

81

1.088 (0.822-1.439)

BVM (reference)

1722

1.000

784

1.000

Age

Female

11738

482 (4.1)

177 (1.5)

Male

20775

1502 (7.2)

741 (3.6)

aOR, adjusted odds ratio; CI, confidence interval.

Adjusted co-variables: gender, age, initial rhythm, arrest location, witnessed status, by-

19-49

4639

548 (11.8)

322 (6.9)

stander CPR, prehospital AED shock, community urbanization, level of ED, EMS response

50-69

11153

955 (8.6)

474 (4.2)

time, scene time, and transport time, Prehospital ROSC.

N 70

16721

481 (2.9)

122 (0.7)

Witnessed arrest

Yes

14758

1478 (10)

747 (5.1)

No

17755

506 (2.8)

171 (1)

Bystander CPR

Yes

2708

423 (15.6)

265 (9.8)

clinical outcomes only for the patients whose arrest was not witnessed.

No

29805

1561 (5.2)

653 (2.2)

It is unclear why the clinical outcomes were better for the patients

higher among the patients who received ETI compared with those who underwent BVM or SGA. Interestingly, analysis of the interaction model results according to witnessed status revealed that ETI resulted in good

AED shock

Yes

3488

949 (27.2)

603 (17.3)

No

29025

1035 (3.6)

315 (1.1)

Initial rhythm

Shockable

2344

781 (33.3)

545 (23.3)

brillation [13-15], ETI is obviously a definitive airway management

PEA

2190

221 (10.1)

66 (3.0)

technique that greatly facilitates Gas exchange and enables continuous

who received ETI than for those who underwent BVM or SGA. Although approximately 20% of prehospital intubation attempts may fail and ETI might result in interruptions in chest compressions and delayed defi-

Asystole 27979 982 (3.5) 307 (1.1)

Arrest location

Public 4519 553 (12.2) 274 (6.1)

Home

23857

1167 (4.9)

496 (2.1)

ETI lead to improved survival [17-19].

Unknown

4137

264 (6.4)

148 (3.6)

According to the 3-phase time-sensitive model postulated by

chest compressions once it is successfully performed [16]. There is also evidence that minimal interruptions to CPR and delays in performing

Metropolitan

Yes

15192

1199 (7.9)

562 (3.7)

No

17321

785 (4.5)

356 (2.1)

esponse time

b4 min 2646 236 (8.9) 130 (4.9)

4-8 min

17764

1239 (7.0)

570 (3.2)

8-12 min

7555

417 (5.5)

172 (2.3)

N 12 min

4548

92 (2.0)

46 (1.0)

R

Scene time

Weisfeldt and Becker [20], ETI may have a stronger influence on good clinical outcomes during the circulatory phase, which occurs from ap- proximately 4 to 10 minutes of ventricular fibrillation (the most impor- tant life-saving technique may be CPR, followed by defibrillation, during this phase), in contrast with the electrical phase, which occurs from cardi- ac arrest until approximately 4 minutes (the most important life-saving therapy is immediate defibrillation during this phase) [21]. In this study,

b4 min

4579

385 (8.4)

151 (3.3)

the likelihood of neurologically favorable survival to discharge was signif-

4-8 min

13040

793 (6.1)

372 (2.9)

icantly higher for the ETI group compared with the BVM group, but only

8-12 min

9108

511 (5.6)

252 (2.8)

for the patients with an unwitnessed arrest. This finding suggests that

N 12 min

Transport time

b4 min

5786

4502

295 (5.1)

317 (7.0)

143 (2.5)

150 (3.3)

ETI might be more helpful during the circulatory phase.

In our study, the airway management groups classified as ETI, SGA, and

4-8 min

14421

955 (6.6)

410 (2.8)

BVM were defined by the airway management technique that was applied

8-12 min

6941

370 (5.3)

170 (2.4)

at the time of arrival at the ED. We could not determine the reason why

N 12 min

ED level 1

6649

2784

342 (5.1)

319 (11.5)

188 (2.8)

162 (5.8)

each specific airway management technique was chosen. For example, pa- tients with rapid return of spontaneous circulation might be more likely to

2

10278

833 (8.1)

349 (3.4)

receive ETI as a definitive airway management technique [22], and patients

3

19451

832 (4.3)

407 (2.1)

who undergo BVM might have had a poor prognosis, as determined during

the first resuscitation attempt and are therefore more likely to receive this

this adjusted interaction model demonstrated negative associations be- tween SGA and the study outcomes for the patients with an unwitnessed arrest in contrast with BVM (adjusted OR, 0.669; 95% CI, 0.491-0.911, for survival to discharge; and adjusted OR, 0.565; 95% CI, 0.337-0.945, for

Table 4

Effects of airway management on clinical outcomes in interaction model with witnessed status

neurologically favorable survival to discharge) (Table 4).

Survival discharge (n = 1984)

Discharge with good neurologic outcome (n = 918)

Discussion

McMullan’s study of the large, US multicenter The Cardiac Arrest Reg- istry to Enhance Survival (CARES) registry and Hasegawa’s study of a Japanese nationwide OHCA cohort revealed that survival was higher among patients who did not receive advanced airway management compared with those who did receive it [3,4]. In Gausche’s randomized controlled study of pediatric OHCA, Prehospital ETI performed by para- medics did not improve survival or neurological outcomes [12].

Witnessed

ETI

77

1.133

(0.931-1.380)

41

1.110

(0.848-1.452)

SGA

128

1.020

(0.858-1.212)

72

1.024

(0.813-1.290)

BVM (reference)

1273

1.000

634

1.000

Unwitnessed ETI

31

1.735

(1.291-2.332)

12

1.954

(1.213-3.148)

SGA

26

0.669

(0.491-0.911)

9

0.565

(0.337-0.945)

BVM (reference)

449

1.000

150

1.000

n aOR (95% CI) n aOR (95% CI)

Our major findings in this analysis of a nationwide, population-based OHCA registry are different from those of the abovementioned previous studies. In our study, neurologically favorable survival to discharge was

aOR, adjusted odds ratio; CI, confidence interval.

Adjusted co-variables: gender, age, initial rhythm, arrest location, witnessed status, by- stander CPR, prehospital AED shock, community urbanization, level of ED, EMS response time, scene time, transport time, and prehospital ROSC.

management technique. [23,24] In contrast, patients for whom advanced airway management has failed might be reverted to BVM.

Important differences were found in the arrest demographics be- tween our cohort and the CARES registry. Field termination of resuscita- tion (TOR) cases comprised up to one-third of the CARES cohort. However, field TOR is not permitted in Korea, similar to Japan [3,4]. Al- though only 3.7% of our cohort underwent ETI, 53% were managed with ETI in the CARES cohort. Among the patients who received ETI, survival to ED admission was also quite lower in our cohort than in the CARES co- hort (6.4% vs 26.6%, respectively), although the survival to discharge rates were similar (9.0% vs 8.3%, respectively), and the on-scene time for our cohort was less than half of that for the CARES cohort (10 minutes vs 23 minutes, respectively) [4]. These differences were thought to result from EMS system maturity, which varies from country to country.

Although we performed adjustments for the Utstein variables that are known as powerful predictors of good clinical outcomes and for potential confounders, such as arrest location, community urbanization, and the ED level, unmeasured and immeasurable confounders may have influenced the patient outcomes. Thus, our results may not be generalizable and should be interpreted with caution in different EMS systems.

Limitations

This study has several limitations. First, the CAVAS database of Korean nationwide EMS-assessed OHCA patients is not designed for gathering in- formation on airway management. Therefore, our cohort lacks details on airway management, such as the number and duration of advanced air- way insertion attempts. We also did not acquire information on whether advanced airway management was performed during CPR or after ROSC. Because the patients with failed advanced airway management attempts were eventually reverted to BVM, these variables were particularly im- portant, but we could not adjust for them as in previous studies. However, the Korean EMS system is government operated, and all of EMTs must abide by the government’s internal regulation, which states that 1 at- tempt should be performed within a single 30-second duration, and up to 2 total advanced airway management attempts can be made on scene. Therefore, the number of cases reverted to BVM after prolonged and multiple advanced airway attempts would be minimal.

Second, although we performed multivariable adjustments for po- tential confounders, some selection biases may have existed. Among a total of 32513 patients, only 3.7% underwent ETI in this study. Thus, we cannot exclude the possibility that some EMTs with good ETI skills performed ETI selectively on patients with a better prognosis, as deter- mined during the first CPR attempt.

Lastly, CPR quality is a strong prognostic factor. The associations be-

tween the prehospital airway management techniques and clinical out- comes might have been greatly confounded by CPR quality. However, CPR quality could not be captured in our CAVAS database. In addition, as with any observational study, our findings might have been confounded by unmeasured and immeasurable factors affecting real-life CPR situations.

Conclusions

In this Korean nationwide, population-based OHCA cohort, the neu- rologically favorable survival to hospital discharge rate was significantly higher for the patients who received ETI compared with those who re- ceived BVM or SGA. In addition, ETI resulted in a good clinical outcomes

only for the patients whose arrest was not witnessed. A multicenter ran- domized controlled study examining the entire airway management process is urgently needed.

References

  1. Stiell IG, Wells GA, Field B, Spaite DW, Nesbitt LP, De Maio VJ, et al. Advanced cardiac life support in out-of-hospital cardiac arrest. N Engl J Med 2004;351:647-56.
  2. Jennings PA, Cameron P, Walker T, Bernard S, Smith K. Out-of-hospital cardiac arrest in Victoria: rural and urban outcomes. Med J Aust 2006;185:135-9.
  3. Hasegawa K, Hiraide A, Chang Y, Brown DF. Association of prehospital advanced air- way management with neurologic outcome and survival in patients with out-of- hospital cardiac arrest. JAMA 2013;309:257-66.
  4. McMullan J, Gerecht R, Bonomo J, Robb R, McNally B, Donnelly J, et al. Airway man- agement and out-of-hospital cardiac arrest outcome in the CARES registry. Resusci- tation 2014;85:617-22.
  5. Fouche PF, Simpson PM, Bendall J, Thomas RE, Cone DC, Doi SA. Airways in out-of- hospital cardiac arrest: systematic review and meta-analysis. Prehosp Emerg Care 2014;18:244-56.
  6. Benoit JL, Gerecht RB, Steuerwald MT, McMullan JT. Endotracheal intubation versus supraglottic airway placement in out-of-hospital cardiac arrest: A meta-analysis. Re- suscitation 2015;93:20-6.
  7. Deakin CD, Nolan JP, Soar J, Sunde K, Koster RW, Smith GB, et al. European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support. Resus- citation 2010;81:1305-52.
  8. Neumar RW, Otto CW, Link MS, Kronick SL, Shuster M, Callaway CW, et al. Part 8: Adult Advanced Cardiovascular Life Support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010;122:S729-67.
  9. Wang HE, Mann NC, Mears G, Jacobson K, Yearly DM. Out-of-hospital airway man- agement in the United States. Resuscitation 2011;82:378-85.
  10. Shin SD, Ong ME, Tanaka H, Ma MH, Nishiuchi T, Alsakaf O, et al. Comparison of emergency medical services systems across Pan-Asian countries: a Web-based Sur- vey. Prehosp Emerg Care 2012;16:477-96.
  11. ILCOR Task Force on Cardiac Arrest and Cardiopulmonary Resuscitation Outcomes. Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and sim- plification of the Utstein templates for resuscitation registries: a statement for healthcare professionals from a task force of the International Liaison Committee on Resuscitation. Circulation 2004;110:3385-97.
  12. Gausche M, Lewis RJ, Stratton SJ, Haynes BE, Gunter CS, Goodrich SM, et al. Effect of out-of-hospital pediatric endotracheal intubation on survival and neurological out- come: a controlled clinical trial. JAMA 2000;283:783-90.
  13. Wang HE, Yealy DM. How many attempts are required to accomplish out-of-hospital endotracheal intubation? Acad Emerg Med 2006;13:372-7.
  14. Hoyle Jr JD, Jones JS, Deibel M, Lock DT, Reischman D. Comparative study of airway management techniques with restricted access to patient airway. Prehosp Emerg Care 2007;11:330-6.
  15. Abo BN, Hostler D, Wang HE. Does the type of out-of-hospital airway interfere with other cardiopulmonary resuscitation tasks? Resuscitation 2007;72:234-9.
  16. Benoit JL, Prince DK, Wang HE. Mechanisms linking advanced airway management and Cardiac arrest outcomes. Resuscitation 2015;93:124-7.
  17. Garza AG, Gratton MC, Salomone JA, Lindholm D, McElroy J, Archer R, et al. Improved patient survival using a modified Resuscitation protocol for out-of-hospital cardiac arrest. Circulation 2009;119:2597-605.
  18. Kellum MJ, Kennedy KW, Barney R, Keilhauer FA, Bellino M, Zuercher M, et al. Cardiocerebral resuscitation improves Neurologically intact survival of patients with out-of-hospital cardiac arrest. Ann Emerg Med 2008;52: 244-52.
  19. Kellum MJ, Kennedy KW, Ewy GA. Cardiocerebral resuscitation improves survival of patients with out-of-hospital cardiac arrest. Am J Med 2006;119:335-40.
  20. Weisfeldt ML, Becker LB. Resuscitation after cardiac arrest: a 3-phase time-sensitive model. JAMA 2002;288:3035-8.
  21. Valenzuela TD, Roe DJ, Cretin S, Spaite DW, Larsen MP. Estimating effectiveness of cardiac arrest interventions: a logistic regression survival model. Circulation 1997; 96:3308-13.
  22. Adams JN, Sirel J, Marsden K, Cobbe SM. Heartstart Scotland: the use of paramedic skills in out of hospital resuscitation. Heart 1997;78:399-402.
  23. Holmberg M, Holmberg S, Herlitz J. Low chance of survival among patients requiring adrenaline (epinephrine) or intubation after out-of-hospital cardiac arrest in Sweden. Resuscitation 2002;54:37-45.
  24. Studnek JR, Thestrup L, Vandeventer S, Ward SR, Staley K, Garvey L, et al. The asso- ciation between prehospital endotracheal intubation attempts and survival to hospi- tal discharge among out-of-hospital cardiac arrest patients. Acad Emerg Med 2010; 17:918-25.

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