D-Dimer and Exhaled CO2/O-2 to Detect Segmental Pulmonary Embolism in Moderate-Risk Patients

作者：Kline Jeffrey A^*; Hogg Melanie M; Courtney D Mark; Miller Chadwick D; Jones Alan E; Smithline Howard A; Klekowski Nicole; Lanier Randy

来源：American Journal of Respiratory and Critical Care Medicine, 2010, 182(5): 669-675.

DOI：10.1164/rccm.201001-0129OC

• fibrin fragment D
• venous thromboembolism
• medical decision making
• capnography
• tomography, spiral computed

Rationale Pulmonary embolism (PE) decreases the exhaled end-tidal ratio of carbon dioxide to oxygen (etCO(2)/O-2).
Objectives: To test if the etCO(2)/O-2 can produce clinically important changes in the probability of segmental or larger PE on computerized tomography multidetector-row pulmonary angiography (MDCTPA) in a moderate-risk population with a positive D-dimer.
Methods: Emergency department and hospitalized patients with one or more predefined symptoms or signs, one or more risk factors for PE, and 64-slice MDCTPA enrolled from four hospitals. D-dimer greater than 499 ng/ml was test(+), and D-dimer less than 500 ng/ml was test(-). The median etCO(2)/O-2 less than 0.28 from seven or more breaths was test(+) and etCO(2)/O-2 greater than 0.45 was test(-). MDCTPA images were read by two independent radiologists and the criterion standard was the interpretation of acute PE by either reader. PE size was then graded.
Measurements and Main Results: We enrolled 495 patients, including 60(12%) with segmental or larger, and 29(6%) with subseg menta I PE. A total of 367 (74%) patients were D-dimer(+), including all 60 with segmental or larger PE (posterior probability 16%). The combination of D-dimer(+) and etCO(2)/O-2(+) increased the posterior probability of segmental or larger PE to 28% (95% confidence interval [CI] for difference of 12%, 3.0-22%). The combination of D-dimer(+) and etCO(2)/O-2(-) was observed in 40 patients (8%-; 95% CI, 6-11%), and none (0/40; 95% Cl, 0-9%) had segmental or larger PE on MDCTPA. No strategy changed the prevalence of subsegmental PE.
Conclusions: In moderate-risk patients with a positive D-dimer, the et etCO(2)/O-2 less than 0.28 significantly increases the probability of segmental or larger PE and the etCO(2)/O-2 greater than 0.45 predicts the absence of segmental or larger PE on MDCTPA.

• 出版日期2010-9-1
• 单位西北大学