End-Tidal Carbon Dioxide Measurement in Out-of-Hospital Cardiac Arrest as a Predictor of Return of Spontaneous Circulation: A Literature Review

Introduction: One of the leading causes of morbidity and mortality worldwide is out-of-hospital cardiac arrest. Early defibrillation and high-quality cardiopulmonary resuscitation (CPR) have improved survival. The main goal of CPR is to achieve return of spontaneous circulation (ROSC), which is assessed by looking for a pulse, analyzing the heart rhythm, and assessing carbon dioxide levels. The use of cartography during CPR to confirm the correct position of the endotracheal tube during intubation or to assess the effectiveness of chest compressions has increased significantly in the last years. The aim of this review was to identify correlations between end-tidal carbon dioxide levels and the likelihood of ROSC in patients with out-of-hospital cardiac arrest.

Methods: A literature search was performed in MEDLINE (via Pubmed), Scopus, Web of Science, and Google Scholar databases from September to November 2022. Keywords combined with the Boolean operators (AND/OR) were used in both free text and Medical Subject Headings. Studies on adult patients published between 01/01/2016 and 28/09/2022 were searched, with no geographical restrictions.

Results: At the end of the selection process, 14 studies were included that investigated capnography in out-of-hospital CPR and reported at least 1 outcome between end-tidal carbon dioxide and ROSC or survival.

Discussion: Capnography is an advantageous tool due to its noninvasive characteristics, ease of use, and immediacy of data. In out-of-hospital cardiac arrest, the use of the end-tidal carbon dioxide appears to be an appropriate complementary tool to support clinical decisions, such as correct positioning of the endotracheal tube, optimizing ventilation in CPR, and as a predictor of ROSC.