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

BACKGROUND: The study prospectively assesses deadspace [(arterial CO2 - end -tidal CO2)/arterial CO2] and the D-dimer assay as a rapid, noninvasive alt ernative for evaluating pulmonary embolism in critically ill patients. METHODS: Group I patients had nonemergency baseline arterial blood gas and end-tidal CO2 recorded. If patients experienced respiratory distress, D-dim er with repeat arterial blood gas and end-tidal CO2 were obtained. Patients emergently intubated without baseline laboratory studies (group II) had ar teria( blood gas, end-tidal CO2, and D-dimer obtained. RESULTS: A significant increase (P <0.001) in deadspace was noted with pulm onary embolism (0.43 [0.08], range 0.30 to 0.51, n = 7) versus without (0.2 1 [0.15], range 0.00 to 0.43, n = 14). Patients in group 1 with pulmonary e mbolism demonstrated increased deadspace (P <0.026, 0.28 [0.01] to 0.39 [0. 13], n = 2) from baseline compared with decreased deadspace (P <0.001, 0.20 [0.09] to 15 [0.16], n = 9) without pulmonary embolism. D-dimer levels >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. Am J Surg. 1999;178:9 8-102. (C) 1999 by Excerpta Medica, Inc.