Diagnostic accuracy of noninvasive end-tidal carbon dioxide measurement in emergency department patients with suspected pulmonary embolism84-90

Turk J Med Sci. 2016 Jan 5;46(1):84-90. doi: 10.3906/sag-1404-108.


Background/aim: Pulmonary embolism (PE) is a frequent health problem representing a diagnostic challenge with high mortality and morbidity rates. The aim of this study was to investigate the value of end-tidal carbon dioxide (ETCO2) and alveolar dead space fraction (ADSF) in the diagnosis of PE.

Materials and methods: ETCO2 levels of patients with suspected PE were measured with a noninvasive mainstream sensor. ADSF of patients was calculated and PaCO2 levels were also obtained. ROC curve analysis was used to determine diagnostic values of ETCO2 and ADSF for PE.

Results: The study included 159 patients. The mean values for ETCO2 and ADSF were 16.27 (95% CI, 14.52-18.03) and 0.48 (95% CI, 0.43-0.539) in the PE group and 21.57 (95% CI, 20.52-22.639) and 0.35 (95% CI, 0.32-0.38) in the non-PE group. The area under the curve (AUC) and the cut-off point for ETCO2 were found as 0.751 and ≤19, with 83.8% sensitivity and 61.5% specificity. AUC and cut-off point for ADSF were found as 0.738 and >0.443, with 67.57% sensitivity and 73.77% specificity.

Conclusion: The diagnostic value of calculated ADSF and noninvasive bedside ETCO2 for PE was found to be low.

Keywords: Pulmonary embolism; alveolar dead space fraction; emergency department; end-tidal carbon dioxide.

MeSH terms

  • Carbon Dioxide / analysis*
  • Emergency Service, Hospital
  • Humans
  • Prospective Studies
  • Pulmonary Embolism
  • Sensitivity and Specificity


  • Carbon Dioxide