[The end-tidal carbon dioxide as an early sign and predictor of the return of spontaneous circulation during out-of-hospital cardiac arrest. A systematic review.].

Background: There is no clear evidence on the maximum level of end-tidal carbon dioxide (ETCO) predictor of the return of spontaneous circulation (RSC) after an out-of-hospital cardiorespiratory arrest. The aims of this work was to synthesise and analyse the available evidence on the usefulness of monitoring values ETCO in an out-of-hospital cardiorespiratory arrest as an early sign and prognostic indicator of the RSC.

Methods: Systematic review, with narrative synthesis of the results, of primary studies published in English or Spanish was conducted in Medline, CINAHL, Web of Science, EMBASE, Proquest, Scopus, Cochrane, ÍnDICEs CSIC and CUIDEN of studies that analyse the usefulness of monitoring of the level of ETCO as a sign of the RSC after an out-of-hospital cardiorespiratory arrest. PRISMA declaration was followed. The risk of bias was assessed with the Newcastle-Ottawa Scale.

Results: 1,011 studies were found, eight of which fulfilled the inclusion criteria. The studies reported an association between the abrupt increase in ETCO and RSC to disagree on the predictive cut-off points (an increase than 10 mmHg and initial values or three minutes greater than 10 mmHg or 19 mmHg). The studies were of moderate to high methodological quality.

Conclusions: ETCO values correlate with the RSC in adults with cardiorespiratory arrest and could predict non-survival, so they should be incorporated into advanced life support algorithms and Utstein-style reports.