Evaluation of suspected pulmonary embolism utilizing end-tidal CO2 and D-dimer

Abstract Background: The study prospectively assesses deadspace [(arterial CO 2 − end-tidal CO 2 )/arterial CO 2 ] and the D-dimer assay as a rapid, noninvasive alternative for evaluating pulmonary embolism in critically ill patients. Methods: Group I patients had nonemergency baseline arterial blood gas and end-tidal CO 2 recorded. If patients experienced respiratory distress, D-dimer with repeat arterial blood gas and end-tidal CO 2 were obtained. Patients emergently intubated without baseline laboratory studies (group II) had arterial blood gas, end-tidal CO 2 , and D-dimer obtained. Results: A significant increase ( P increased deadspace ( P decreased deadspace ( P 1,000 ng/mL were present in all patients with pulmonary embolism. Conclusions: The study demonstrates the ability of deadspace and D-dimer to exclude and potentially diagnose pulmonary embolism.