Kline J A, Meek S, Boudrow D, Warner D, Colucciello S
Department of Emergency Medicine, Carolinas Medical Center, Charlotte, NC 28232-2861, USA.
Acad Emerg Med. 1997 Sep;4(9):856-63. doi: 10.1111/j.1553-2712.1997.tb03809.x.
To evaluate the utility of a modified calculation of the alveolar dead space fraction (Vd/Vt), combined with plasma D-dimers, to aid in the exclusion of acute pulmonary embolism (PE).
A prospective comparison of screening modalities was performed in a metropolitan teaching ED. Ambulatory patients evaluated for PE underwent simultaneous end-tidal CO2 and arterial blood gas determinations, as well as venous latex-agglutination D-dimer quantification. The modified Bohr equation was used to calculate Vd/Vt as an index of alveolar dead space. Acute PE was diagnosed or excluded using appropriate combinations of clinical suspicion, ventilation-perfusion lung scanning, lower-extremity venous Doppler ultrasonography, pulmonary angiography, and comprehensive follow-up.
Of 170 subjects studied, PE was confirmed (PE+) in 26 (15%) and excluded (PE-) in 144 (85%). In the PE+ group, Vd/Vt was 0.31 +/- 0.13 (mean +/- SD), and in the PE- group, Vd/Vt was 0.06 +/- 0.10 (p < 0.05, t-test). Regarding false-negative rates, Vd/Vt was normal (i.e., < 0.2) in 3/26 PE+ patients and D-dimer concentrations were normal (< 0.5 microgram/L) in 4/26 patients in the PE+ group. The combination of a normal Vd/Vt and D-dimer concentration was 100% sensitive (95% CI = 88-100%) in excluding PE. False-positive testing (either test positive) occurred in 49/144 subjects (specificity 65%, 95% CI = 52-73%). The age-adjusted alveolar-arterial O2 gradient was 33 +/- 38 torr in the PE+ group vs 13 +/- 37 torr in the PE- group (p = 0.11).
In ambulatory patients, the finding of Vd/Vt < 0.2 and D-dimers < 0.5 microgram/L lowers the probability of acute PE.
评估改良计算的肺泡死腔分数（Vd/Vt）联合血浆D - 二聚体在排除急性肺栓塞（PE）中的作用。
在一个大城市教学医院急诊科对筛查方式进行前瞻性比较。对因PE接受评估的门诊患者同时进行呼气末二氧化碳和动脉血气测定，以及静脉乳胶凝集法D - 二聚体定量检测。使用改良的玻尔方程计算Vd/Vt作为肺泡死腔的指标。通过临床怀疑、通气 - 灌注肺扫描、下肢静脉多普勒超声、肺血管造影及全面随访的适当组合来诊断或排除急性PE。
在170名研究对象中，26名（15%）确诊为PE（PE +），144名（85%）排除PE（PE -）。PE +组中，Vd/Vt为0.31±0.13（均值±标准差），PE -组中，Vd/Vt为0.06±0.10（p < 0.05，t检验）。关于假阴性率，26名PE +患者中有3名Vd/Vt正常（即< 0.2），26名患者中有4名PE +组患者D - 二聚体浓度正常（< 0.5微克/升）。Vd/Vt和D - 二聚体浓度均正常在排除PE方面敏感性为100%（95%可信区间 = 88 - 100%）。49/144名受试者出现假阳性检测（任一检测阳性）（特异性65%，95%可信区间 = 52 - 73%）。PE +组年龄校正后的肺泡 - 动脉氧梯度为33±38托，PE -组为13±37托（p = 0.11）。
在门诊患者中，Vd/Vt < 0.2且D - 二聚体< 0.5微克/升可降低急性PE的可能性。
