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This prospective observational study evaluated the association of prehospital endotracheal intubation (ETI) status with return of spontaneous circulation (ROSC), 28-day survival, and favorable neurological outcome in adult patients with out-of-hospital cardiac arrest (OHCA) transported to the emergency department (ED) by emergency medical services (EMS). In addition, the study investigated the causes of failed ETI attempts and examined other clinical factors associated with 28-day survival, including bystander cardiopulmonary resuscitation (CPR), initial cardiac rhythm, blood gas parameters, and prehospital airway management strategy.
This prospective observational cohort study was conducted in the ED of Haseki Training and Research Hospital between July 1, 2025, and December 31, 2025. Patients presenting to the ED with cardiac arrest during the study period were screened for eligibility. All patients received advanced cardiac life support (ACLS) in accordance with the 2025 European Resuscitation Council (ERC) guidelines.
Data collected for each patient encompassed demographic characteristics (age, sex, and body mass index [BMI]) and comorbid conditions, including hypertension, diabetes mellitus, coronary artery disease, chronic kidney disease, and malignancy. Prehospital variables included witnessed arrest, bystander CPR, bystander automated external defibrillator (AED) use, no-flow duration, time from collapse to initiation of advanced life support (ALS), time from collapse to hospital arrival, hyperventilation, and initial cardiac rhythm (asystole/pulseless electrical activity [PEA] or ventricular fibrillation/pulseless ventricular tachycardia [VF/pVT]). Prehospital airway data were recorded in two ways: the airway device present on ED arrival (endotracheal tube in place, bag-valve-mask ventilation, or supraglottic airway) and prehospital ETI attempt status (successful ETI, failed ETI attempt, or no ETI attempt). ETI success and the reasons for failed ETI attempts were also recorded, as was the occurrence of prehospital ROSC.
Upon arrival at the ED, body temperature, Glasgow Coma Scale (GCS) score (when assessable), and vasopressor use within the first hour were recorded. Arterial blood gas parameters, including pH, partial pressure of oxygen (PaO2), and partial pressure of carbon dioxide (PaCO2), were also documented. Clinical outcomes included ROSC, 28-day survival status, and neurological outcome.
Patients were classified as survivors or non-survivors according to 28-day survival status. Demographic characteristics, comorbidities, prehospital time intervals, initial rhythm, blood gas parameters, and airway management variables were compared across these groups to identify factors associated with 28-day survival. For airway-specific analyses, patients were further categorized into three groups according to ETI status: successful ETI, failed ETI attempt, and no ETI attempt. Comparisons among these groups were performed to assess differences in demographic and clinical characteristics, prehospital resuscitation variables, ROSC, 28-day survival, and favorable neurological outcome according to ETI status.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Survivors | Survivors were defined as the patient being alive at 28 days following the cardiac arrest event. |
| |
| Non-survivors | Non-survivors had passed away within 28 days following the cardiac arrest event. |
| |
| Successful ETI | Adult patients with out-of-hospital cardiac arrest (OHCA) who underwent a successful prehospital endotracheal intubation (ETI) attempt by emergency medical services (EMS) personnel before arrival at the emergency department (ED). |
| |
| Failed ETI attempt | Adult patients with OHCA who underwent a failed prehospital ETI attempt by EMS personnel before arrival at the ED. |
| |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Demographics | Other | The demographic profile of each patient was documented, including age and sex, to examine potential associations with survival and neurological outcomes. |
|
| Measure | Description | Time Frame |
|---|---|---|
| 28 day-survival rate | Survival status at day 28 after advanced cardiovascular life support (ACLS) initiated following out-of-hospital cardiac arrest (OHCA). Participants will be classified as survivors if alive on day 28 and as non-survivors if death occurs within 28 days. | At 28 days after ACLS initiation following OHCA. |
| Measure | Description | Time Frame |
|---|---|---|
| Neurological Status at 28 Days | Neurological status assessed 28 days after ACLS initiation following OHCA using the Cerebral Performance Category (CPC) scale. Favorable neurological outcome will be defined as CPC 1-2, and unfavorable neurological outcome as CPC 3-5. | At 28 days after ACLS initiation following OHCA |
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Inclusion Criteria:
Exclusion Criteria:
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This study included 361 adult patients (aged ≥18 years) who were brought to our hospital's ED due to OHCA and who had initiated attempted resuscitation by EMS were initially screened for inclusion between July 1, 2025, and December 31, 2025.
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| Name | Affiliation | Role |
|---|---|---|
| Adem Az | Sultangazi Haseki Eğitim ve Araştırma Hastanesi, Başhekimlik | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Haseki Training and Research Hospital | Sultangazi | Istanbul | 34265 | Turkey (Türkiye) |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 30167701 | Result | Benger JR, Kirby K, Black S, Brett SJ, Clout M, Lazaroo MJ, Nolan JP, Reeves BC, Robinson M, Scott LJ, Smartt H, South A, Stokes EA, Taylor J, Thomas M, Voss S, Wordsworth S, Rogers CA. Effect of a Strategy of a Supraglottic Airway Device vs Tracheal Intubation During Out-of-Hospital Cardiac Arrest on Functional Outcome: The AIRWAYS-2 Randomized Clinical Trial. JAMA. 2018 Aug 28;320(8):779-791. doi: 10.1001/jama.2018.11597. | |
| 30167699 |
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Stored in non-publicly avaliableAvaliable on request
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| ID | Term |
|---|---|
| D058687 | Out-of-Hospital Cardiac Arrest |
| D006323 | Heart Arrest |
| ID | Term |
|---|---|
| D006331 | Heart Diseases |
| D002318 | Cardiovascular Diseases |
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| ID | Term |
|---|---|
| D003710 | Demography |
| D015897 | Comorbidity |
| ID | Term |
|---|---|
| D011154 | Population Characteristics |
| D015991 | Epidemiologic Measurements |
| D011634 | Public Health |
| D004778 | Environment and Public Health |
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| No ETI attempt |
Adult patients with OHCA in whom no prehospital ETI attempt was performed by EMS personnel before arrival at the ED. |
|
| Comorbidities | Other | Data on pre-existing chronic conditions were recorded, such as hypertension, diabetes mellitus, coronary artery disease, chronic kidney disease, and malignancy, in order to assess their potential impact on prognosis following OHCA. |
|
| Prehospital Variables | Other | Several prehospital factors were evaluated, including whether the cardiac arrest was witnessed, whether bystander cardiopulmonary resuscitation (CPR) was performed, the time from collapse to the initiation of CPR, and the time from collapse to EMS arrival. Additionally, the durations of no-flow (i.e., time without any CPR) and low-flow (i.e., time with CPR but without ROSC) were noted. The initial cardiac rhythm was categorized as ventricular fibrillation or pulseless ventricular tachycardia (VF/pVT), asystole, or pulseless electrical activity (PEA). Airway management methods used in the field were documented and classified as bag-valve-mask (BVM), supraglottic airway devices (SGAs), or endotracheal intubation (ETI). Other recorded interventions included prehospital defibrillation, administration of epinephrine (including total dosage), and use of mechanical chest compression devices. Whether ROSC was achieved prior to arrival at the emergency department was also noted. |
|
| Arterial Blood Gas Parameters | Diagnostic Test | Arterial blood gas parameters, including pH, partial pressure of oxygen (PaO2), and partial pressure of carbon dioxide (PaCO2), were also documented. |
|
| 28-day survival | Other | Survival status 28 days after advanced cardiac life support (ACLS) initiated following OHCA. |
|
| Neurological outcome | Other | Neurological status assessed at day 28 using the Cerebral Performance Category (CPC) scale. Favorable neurological outcome was defined as CPC 1-2, and unfavorable neurological outcome was defined as CPC 3-5. |
|
| Achievement of Return of Spontaneous Circulation (ROSC) During Resuscitation Following Out-of-Hospital Cardiac Arrest (OHCA). |
ROSC was defined as the return of sustained spontaneous perfusing rhythm lasting at least 20 minutes without the need for external chest compressions. |
| Assessed within the first 20 minutes after emergency department admission. |
| Comparison of 28-Day Survival Rates Between Participants Who Underwent Prehospital Endotracheal Intubation and Those Who Did Not | The investigators evaluate the impact of prehospital endotracheal intubation (ETI) on 28-day survival status. Survival was defined as being alive 28 days after the cardiac arrest event. Participants will be categorized into two groups based on whether or not they received ETI in the prehospital setting. | At 28 days after ACLS initiation following OHCA |
| Result |
| Wang HE, Schmicker RH, Daya MR, Stephens SW, Idris AH, Carlson JN, Colella MR, Herren H, Hansen M, Richmond NJ, Puyana JCJ, Aufderheide TP, Gray RE, Gray PC, Verkest M, Owens PC, Brienza AM, Sternig KJ, May SJ, Sopko GR, Weisfeldt ML, Nichol G. Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial. JAMA. 2018 Aug 28;320(8):769-778. doi: 10.1001/jama.2018.7044. |
| 29486039 | Result | Jabre P, Penaloza A, Pinero D, Duchateau FX, Borron SW, Javaudin F, Richard O, de Longueville D, Bouilleau G, Devaud ML, Heidet M, Lejeune C, Fauroux S, Greingor JL, Manara A, Hubert JC, Guihard B, Vermylen O, Lievens P, Auffret Y, Maisondieu C, Huet S, Claessens B, Lapostolle F, Javaud N, Reuter PG, Baker E, Vicaut E, Adnet F. Effect of Bag-Mask Ventilation vs Endotracheal Intubation During Cardiopulmonary Resuscitation on Neurological Outcome After Out-of-Hospital Cardiorespiratory Arrest: A Randomized Clinical Trial. JAMA. 2018 Feb 27;319(8):779-787. doi: 10.1001/jama.2018.0156. |
| 30293843 | Result | White L, Melhuish T, Holyoak R, Ryan T, Kempton H, Vlok R. Advanced airway management in out of hospital cardiac arrest: A systematic review and meta-analysis. Am J Emerg Med. 2018 Dec;36(12):2298-2306. doi: 10.1016/j.ajem.2018.09.045. Epub 2018 Sep 26. |
| 29483086 | Result | Pollack RA, Brown SP, Rea T, Aufderheide T, Barbic D, Buick JE, Christenson J, Idris AH, Jasti J, Kampp M, Kudenchuk P, May S, Muhr M, Nichol G, Ornato JP, Sopko G, Vaillancourt C, Morrison L, Weisfeldt M; ROC Investigators. Impact of Bystander Automated External Defibrillator Use on Survival and Functional Outcomes in Shockable Observed Public Cardiac Arrests. Circulation. 2018 May 15;137(20):2104-2113. doi: 10.1161/CIRCULATIONAHA.117.030700. Epub 2018 Feb 26. |
| 26061835 | Result | Hasselqvist-Ax I, Riva G, Herlitz J, Rosenqvist M, Hollenberg J, Nordberg P, Ringh M, Jonsson M, Axelsson C, Lindqvist J, Karlsson T, Svensson L. Early cardiopulmonary resuscitation in out-of-hospital cardiac arrest. N Engl J Med. 2015 Jun 11;372(24):2307-15. doi: 10.1056/NEJMoa1405796. |
| 41114924 | Result | Akdemir T, Az A, Dogan Y, Sogut O. Clinical and laboratory predictors of 28-day survival and neurologic outcome in out-of-hospital cardiac arrest: A prospective cohort study. Ir J Med Sci. 2025 Dec;194(6):2485-2495. doi: 10.1007/s11845-025-04121-0. Epub 2025 Oct 20. |
| D015981 | Epidemiologic Factors |
| D011787 | Quality of Health Care |
| D017530 | Health Care Quality, Access, and Evaluation |