Prehospital Advanced Airway Management and Ventilation for Out-of-Hospital Cardiac Arrest with Prehospital Return of Spontaneous Circulation: A Prospective Observational Cohort Study in Japan

Abstract

Background

The relationship among advanced airway management (AAM), ventilation, and oxygenation in patients with out-of-hospital cardiac arrest (OHCA) who achieve prehospital return of spontaneous circulation (ROSC) has not been validated. This study was designed to evaluate ventilation and oxygenation for each AAM technique (supraglottic devices [SGA] or endotracheal intubation [ETI]) using arterial blood gas (ABG) results immediately after hospital arrival.

Methods

This observational cohort study, using data from the Japanese Association for Acute Medicine OHCA Registry, included patients with OHCA with prehospital and hospital arrival ROSC between July 1, 2014, and December 31, 2019. The primary outcomes were the partial pressure of carbon dioxide in the arterial blood (PaCO₂) and partial pressure of oxygen in the arterial blood (PaO₂) in the initial ABG at the hospital for each AAM technique (SGA or ETI) performed by paramedics. The secondary outcome was favorable neurological outcome (cerebral performance category [CPC] 1 or 2) for specific PaCO₂ levels, which were defined as good ventilation (PaCO₂ ≤45 mmHg) and insufficient ventilation (PaCO₂ >45 mmHg).

Results

This study included 1,527 patients. Regarding AAM, 1,114 and 413 patients were ventilated using SGA and ETI, respectively. The median PaCO₂ and PaO₂ levels were 74.50 mmHg and 151.35 mmHg in the SGA group, while 66.30 mmHg and 173.50 mmHg in the ETI group. PaCO₂ was significantly lower in the ETI group than in the SGA group (12.55 mmHg; 95% CI 15.27 to 8.20, P-value < 0.001), while no significant difference was found in PaO₂ by multivariate linear regression analysis. After stabilizing inverse probability of weighting (IPW), the adjusted odds ratio for favorable neurological outcome at 1 month was significant in the good ventilation group compared to the insufficient ventilation cohort (adjusted odds ratio = 2.12, 95%CI: 1.40 to 3.19, P value < 0.001).

Conclusion

The study showed that in OHCA patients with prehospital ROSC, the PaCO₂ levels in the initial ABG were lower in the group with AAM by ETI than in the SGA group. Furthermore, patients with prehospital ROSC and PaCO₂ ≤45 mmHg on arrival had an increased odds of favorable neurological outcome after stabilized IPW adjustment.

Acknowledgments

We would like to thank Editage (www.editage.jp) for English language editing.

Authors’ Contributions

All authors contributed to the conception and design of this study. RN wrote the manuscript, with help from NB and US. RN and US analyzed the data. KS and EN revised the manuscript. All of the authors have read and approved of the final manuscript.

Availability of Data and Materials

Data associated with the results of this study are available from the JAAM OHCA Registry committee. However, there is a restriction on the availability of these data; they were used under a license for this study and are not available to the general public. Hence, the data are available from the authors upon reasonable request and with permission from the JAAM OHCA Registry Committee.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Ethical Approval and Consent to Participate

The JAAM OHCA Registry was approved by the Ethics Committee of Kyoto University Graduate School of Medicine (R1045) and each participating institution. The requirement for informed consent was waived by the Act on the Protection of Personal Information and the Ethical Guidelines for Medical and Health Research Involving Human Subjects of Japan. This study was registered in the UMIN Clinical Trials Registry (UMIN000007528).