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 alternative 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-dimer with repeat arterial blood gas and end-tidal CO2 were obtained. Patients emergently intubated without baseline laboratory studies (group II) had arterial blood gas, end-tidal CO2, and D-dimer obtained.


RESULTS
A significant increase (P <0.001) in deadspace was noted with pulmonary embolism (0.43 [0.08], range 0.30 to 0.51, n = 7) versus without (0.21 [0.15], range 0.00 to 0.43, n = 14). Patients in group 1 with pulmonary embolism 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.
Johanning
J M
JM
Department of Surgery, Saginaw Cooperative Hospitals, Inc., Michigan, USA.
Veverka
T J
TJ
Bays
R A
RA
Tong
G K
GK
Schmiege
S K
SK
D000792:Angiography; D000933:Antifibrinolytic Agents / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis* / Q000097:blood; D016009:Chi-Square Distribution; D003422:Critical Care; D005069:Evaluation Studies as Topic; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration; D012126:Respiratory Dead Space / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology*; D018608:Ultrasonography, Doppler; D014692:Ventilation-Perfusion Ratio
D000933:Antifibrinolytic Agents; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D002245:Carbon Dioxide; D010100:Oxygen