Elsevier

Resuscitation

Volume 104, July 2016, Pages 53-58
Resuscitation

Clinical paper
Abrupt rise of end tidal carbon dioxide level was a specific but non-sensitive marker of return of spontaneous circulation in patient with out-of-hospital cardiac arrest

https://doi.org/10.1016/j.resuscitation.2016.04.018Get rights and content

Abstract

Objective

To evaluate the diagnostic accuracy of an abrupt and sustained increase in end-tidal carbon dioxide (ETCO2) to indicate return of spontaneous circulation (ROSC) during resuscitation of patient with out-of-hospital cardiac arrest.

Design

Cross-sectional study.

Setting

Emergency department of two regional hospitals.

Methods

Patients with age ≥18 years old, suffered non-traumatic out-of-hospital cardiac arrest with active resuscitation and endotracheal intubation performed in emergency department, were included. ETCO2 value was charted throughout resuscitation. Time of ROSC was remarked. ETCO2 levels before and after ROSC were compared. Diagnostic accuracy of ETCO2 rise ≥10 mmHg, ETCO2 rise ≥20 mmHg, and ETCO2 rise to the level ≥40 mmHg were evaluated for indicating ROSC.

Results

ETCO2 level immediately after ROSC was higher as compared to the value before return of circulation (median ETCO2 was 32 mmHg and 41 mmHg respectively, p = 0.033). With ETCO2 rise ≥10 mmHg, the sensitivity was low (33%, 95% CI 22–47%), while specificity was 97% (95% CI 91–99%). Positive and negative predictive values were 83% (95% CI 62–95%) and 74% (95% CI 66–81%) respectively. The diagnostic accuracy was higher in cardiac arrest with presumed non-cardiac etiology (sensitivity 45%, specificity 100%) as compared to those with cardiac etiology (sensitivity 18%, specificity 97%).

Conclusions

The feature of an abrupt rise of ETCO2 was a specific but non-sensitive marker of ROSC in patient with out-of-hospital cardiac arrest.

Introduction

Measurement of end-tidal of carbon dioxide (ETCO2) level was a non-invasive method, recommended in the ACLS resuscitation guidelines of the American Heart Association1, 2 for monitoring the resuscitation process for patients with cardiac arrest. ETCO2 had been recommended as one of the marker for early prognostication of patients with cardiopulmonary arrest.3, 4, 5, 6, 7 The ACLS 2015 guideline stated that ETCO2 after 20 min of cardiopulmonary resuscitation (CPR) is an important early prognosticator.1 The European Resuscitation Council (ERC) resuscitation guideline 2015 also recommended ETCO2 as part of a multi-modal approach to decision-making for ending resuscitative efforts.3

Another use of ETCO2 during resuscitation was to indicate return of spontaneous circulation (ROSC) when there is an abrupt and sustained rise of ETCO2.8, 9, 10, 11, 12, 13 The 2005 ILCOR consensus statement firstly incorporated the abrupt and sustained rise of ETCO2 >40 mmHg as a bedside indicator of ROSC.14 The ERC guideline recommended to withhold the dose of adrenaline if ROSC is suspected during CPR and deliver adrenaline if cardiac arrest is confirmed at the next rhythm check.3 Theoretically, if this is sensitive and specific enough, it would be able to replace regular pulse checks and thus further minimize the interruption of chest compressions. However, there was limited evidence in the literature to evaluate the accuracy of this to indicate ROSC. A retrospective case control study had demonstrated a sudden increase of ETCO2 ≥10 mmHg had 80% sensitivity and 40% specificity indicating ROSC.8 However, there was major limitation of generalization with the study design and inclusion criteria. There is no strong evidence to evaluate the accuracy of the feature of suddenly increased ETCO2 to detect ROSC in patients with OHCA.

The objective of our study was to evaluate the ETCO2 profile for patients of OHCA with or without ROSC, and evaluate the diagnostic characteristics of the features of abrupt increase in ETCO2 in diagnosis of ROSC.

Section snippets

Study design and setting

This is a cross-sectional study, being performed in emergency departments of two regional hospitals in Hong Kong. The study period was from July 2012 to June 2013. The two hospitals provide emergency service for a region with population of over one million. All cardiac arrest patients occurred in the area were delivered by the Emergency Medical Services provided by the Fire Services Department to these two receiving hospitals. All patients were resuscitated on scene by pre-hospital personnel

Results

Totally 178 cases were included. Fig. 1 showed the recruitment of patients and the outcome. With high exclusion rate due to inadequate documentation, comparison between the included cohort and those excluded was required. There were no significant differences with reference to baseline characteristics and outcome between the included cohort and those excluded.

For the included cohort, sixty patients (34%) had ROSC. Table 1 illustrated the characteristics and outcomes. ETCO2 rise was more

Discussion

The value of capnography during resuscitation of cardiopulmonary arrest was first recognized as dated back in 1987 by Garnett et al.11 which stated that ETCO2 was often the first bedside indicator of ROSC. The 2005 AHA guideline started to incorporate the abrupt and sustained rise of ETCO2 >40 mmHg as a bedside indicator of ROSC.14 It was stated in AHA resuscitation guidelines in 2010 that the use of ETCO2 as clinical indicator of ROSC with Level IIa recommendation (LOE B). Nowadays, continuous

Conclusion

The feature of an abrupt rise of ETCO2 was a specific but non-sensitive marker of ROSC in patient with out-of-hospital cardiac arrest.

Conflict of interest statement

All authors did not have conflict of interest with any parties. There was no funding for the research.

References (22)

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    Part 8: adult advanced cardiovascular life support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care

    Circulation

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      However, elevated ETCO2 might be a result of ROSC instead of a predictor of ROSC, and an accurate cut-off value during CPR has not been fully established8,31,33. ETCO2 is variable depending on numerous factors including vasopressor administration, air leaks around an artificial airway, airspace disease with pulmonary shunts, cardiac shunts and PEEP4,8, all of which might cause difficulty in ETCO2 measurement, as demonstrated by the relatively high rate of failed ETCO2 measurement in this study as well as in actual clinical settings9. POP is much more accessible than ETCO2 and can be applied without endotracheal intubation.

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    A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2016.04.018.

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