The accuracy of mainstream end-tidal carbon dioxide levels to predict the severity of chronic obstructive pulmonary disease exacerbations presented to the ED

Introduction: The end-tidal carbon dioxide (ETCO2) measurement was considered as an essential tool for the assessment of several conditions in emergency medicine. However, the diagnostic role of capnography in dyspneic patients still remains unclear. We aimed to analyze the alteration of the ETCO2 levels in chronic obstructive pulmonary disease (COPD) exacerbations and its role in the decision-making process.

Methods: All the individuals who were presented to the emergency department (ED) after COPD exacerbations were prospectively enrolled in the study. The patients were excluded if they refused to give informed consent, intubated after initial assessment, and had uncertain COPD diagnosis. The ETCO2 measurement using a mainstream capnometer was undertaken in the pretreatment and post-treatment period of COPD exacerbations.

Results: A total of 102 patients were enrolled in the study. Pre-ETCO2 and post-ETCO2 levels were positively correlated with arterial partial carbon dioxide pressure levels (r=0.756, P<.001 and r=0.629, P<.001, respectively). The median pre-ETCO2 level was 32.0 (30.5-40.5) in discharged patients and 39.0 (31.0-53.5) in admitted patients. After the initial therapy in the ED was completed, the median post-ETCO2 level was found to be 32.0 (28.0-37.5) in discharged patients and 36.0 (32.0-52.0) in admitted patients. Although a statistically significant difference was observed in the pretreatment period (P=.043), no difference was observed in post-treatment period between ETCO2 levels (P=.107).

Conclusion: End-tidal carbon dioxide levels were higher in admitted patients when compared with discharged patients on arrival to the ED. ETCO2 measurement has very little contributions while evaluating patients with COPD exacerbation in the ED.