Volumetric or time-based capnography for excluding pulmonary embolism in outpatients? - Université de Bretagne Occidentale Access content directly
Journal Articles Journal of Thrombosis and Haemostasis Year : 2010

Volumetric or time-based capnography for excluding pulmonary embolism in outpatients?


BACKGROUND: Volumetric capnography is technically more demanding but theoretically better than the time-based alveolar deadspace fraction (P(a)CO(2) - EtCO(2))/P(a)CO(2) as a bedside diagnostic tool for excluding pulmonary embolism (PE) in outpatients. OBJECTIVE: We compared both diagnostic accuracy in patients with a suspected PE and positive D-dimer enzyme-linked immunosorbent assay results. PATIENTS AND METHODS: In this clinical multicenter trial with prospective inclusion and 3-month follow-up, alveolar deadspace fraction was compared by receiver operating characteristic (ROC) analysis with other parameters derived from volumetric capnography. RESULTS: Capnography was performed in 239 patients, and 205 tests (86%) were conclusive. The incidence of PE was 33%. The alveolar deadspace fraction accuracy expressed with ROC curve analysis was 0.73 +/- 0.04. The diagnostic performances of parameters from volumetric capnography were not significantly better. Sixteen per cent [95% confidence interval (CI) 12-21%] of patients presented a (P(a)CO(2) - EtCO(2))/P(a)CO(2) ratio under the cut-off value of 0.15, with a low clinical probability. This combination excluded PE, with a sensitivity of 96% (95% CI 89-99%) and a negative likelihood ratio of 0.17 (95% CI 0.09-0.33%). CONCLUSION: Volumetric capnography failed to show superiority to alveolar deadspace fraction measurements [(P(a)CO(2) - EtCO(2))/P(a)CO(2)] for exclusion of PE in outpatients with positive D-dimer test results. Future studies should clarify the safety of excluding PE in patients combining low clinical probability with positive D-dimer results and (P(a)CO(2) - EtCO(2))/P(a)CO(2) ratios below the cut-off value of 0.15.

Dates and versions

hal-00677241 , version 1 (07-03-2012)



Franck Verschuren, Olivier Sanchez, Marc Righini, E. Heinonen, Grégoire Le Gal, et al.. Volumetric or time-based capnography for excluding pulmonary embolism in outpatients?. Journal of Thrombosis and Haemostasis, 2010, 8 (1), pp.60-7. ⟨10.1111/j.1538-7836.2009.03667.x⟩. ⟨hal-00677241⟩
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