Clinical outcome of patients with a 'low probability' of pulmonary embolism on ventilation-perfusion lung scan

Lung ventilation and perfusion (V/Q) scintigraphy is usually indicated when pulmonary embolism (PE) is a suspected diagnosis. Typically, V/Q scintigraphic interpretation is reported as a "normal," "low," "intermediate," or "high probability" of PE. Although a "low probability" interpretation does not exclude the diagnosis of PE, it significantly reduces the likelihood. We retrospectively analyzed up to one year of follow-up in 90 patients who were clinically suspected of having PE, but in whom V/Q scintigraphy implied a low probability of PE. None of the 90 patients demonstrated clinical evidence of PE subsequent to the V/Q scan. Our findings suggest that significant pulmonary embolism is uncommon and that the clinical course appears to be predictable in patients with a low probability V/Q scan.     

Diagnostic value of ventilation-perfusion lung scanning in patients with suspected pulmonary embolism

Differing opinions about the value of ventilation-perfusion lung scanning have created controversy concerning the correct approach to the diagnosis of pulmonary embolism. In a prospective study of 305 consecutive patients with clinically suspected pulmonary embolism and abnormal perfusion lung scans, we evaluated the role of ventilation-perfusion lung scanning, pulmonary angiography, and objective testing for venous thrombosis in the diagnostic process. Segmental or greater perfusion defects with ventilation mismatch have a high probability (86 percent) of pulmonary embolism. Contrary to current clinical practice, however, the approach of ruling against pulmonary embolism by a "low probability" scan pattern is incorrect, even with an improved technique for ventilation imaging; the frequency of pulmonary embolism in these patients ranged from 25 to 40 percent. Objective testing for venous thrombosis provides a practical alternative to performing pulmonary angiography in the diagnostic work-up; by providing an endpoint for commencing anticoagulant therapy, a positive result obviates the need for further testing in 20 to 30 percent of patients.     

Clinical utility of D-dimer in patients with suspected pulmonary embolism and nondiagnostic lung scans or negative CT findings

BACKGROUND: The diagnosis of pulmonary embolism is difficult because the clinical diagnosis is nonspecific and all of the objective tests have limitations. The assay for plasma d-dimer may be useful as an exclusion test if results are negative. We conducted a prospective cohort study that evaluated the clinical utility (usefulness) of an automated quantitative d-dimer test in the diagnosis of patients with suspected pulmonary embolism. METHODS: Consecutive eligible patients who had clinically suspected PE with nondiagnostic lung scans or negative helical CT scan of the chest results underwent d-dimer testing. RESULTS: The d-dimer results were negative in 11 of 103 inpatients (10.6%, 95% confidence interval [CI], 5.5 to 18.3%) and 7 of 22 outpatients (31.8%, 95% CI, 13.9 to 54.9%; p = 0.02). CONCLUSIONS: Measurement of plasma d-dimer is of limited clinical utility for inpatients with clinically suspected pulmonary embolism and nondiagnostic lung scans or negative helical CT results at a US academic health center.     

核素肺灌注显像对肺栓塞患者诊断的临床研究

目的 研究放射性核素肺灌注显像在肺动脉栓塞中的价值.方法 对临床怀疑有肺动脉栓塞的21例患者进行了放射性核素肺灌注显像.结果 21例患者中有13例患者出现不同程度的多发肺段血流灌注异常,其中19个肺段出现放射性缺损区,48个肺段出现放射性稀疏区.结论 放射性核素肺灌注显像是诊断肺动脉栓塞一种无创伤性的有效的检查方法.     

肺栓塞时肺灌注显像与肺动脉造影对比动物实验研究

目的 :通过肺栓塞 (PE)动物模型的建立 ,评价肺灌注显像对肺栓塞诊断及疗效观察中的价值。方法 :计算机随机编号 ,取中国实验用小型猪 8头 ,平均体重 16 1± 1 4kg ;建立模型前均行肺灌注显像及选择性肺动脉造影 (CPA) ,取自体猪血 2～ 5ml制血栓 ,通过右心导管将栓子加压注入肺动脉 ;建立PE模型。建立模型后及溶栓治疗后均行肺灌注显像及CPA ,前后采集条件一致。结果 :8头猪造模前CPA均正常 ,肺灌注显像 1例左肺放射性分布不均 ,肺灌注显像特异性 87 5 % (1 8)。 7例存活的模型猪 ,5例造模成功 ,2例不明显 ;以单侧肺观察 ,肺灌注显像与肺动脉造影对比 ,肺灌注显像诊断PE灵敏度 10 0 % ,准确率 90 %。 1例肺动脉造影正常 ,肺灌注显像为亚肺段栓塞 ,与尸检肉眼病理所见一致 ,溶栓后恢复正常血流灌注 ;如果以溶栓治疗有效为标准则准确率增至 10 0 %。溶栓疗效观察肺灌注显像与肺动脉造影二者结果一致。 1例CPA溶通 ,肺灌注显像部分改善 ,尸检证实为部分坏死、实变。结论 :肺灌注显像诊断PE具有很高的敏感性和特异性 ,与肉眼病理所见完全吻合。可作为肺动脉造影前的筛选 ,及临床疗效观察的重要手段     

Residual emboli on lung perfusion scan or multidetector computed tomography after a first episode of acute pulmonary embolism

The rate of resolution of a first episode of pulmonary embolism (PE) is uncertain. A baseline test indicating any residual PE is pivotal in aiding a more accurate diagnosis of recurrent PE. This study aimed to assess the rate and risk factors of residual PE with either multidetector computed tomography imaging (MDCT) or lung perfusion scan (LPS) using a cross-sectional study in which consecutive patients were enrolled with a first objectively documented episode of symptomatic PE, and who were considered for possible treatment withdrawal after at least 3 months of anticoagulation. A first cohort of patients (n = 80) underwent MDCT, while the subsequent cohort (n = 93) underwent LPS. The two cohorts had similar characteristics, and 98.3% of patients had non high-risk index PE. MDCT detected residual PE in 15% of subjects (12/80, 95% CI 8–25%) after a mean of 9 months of anticoagulation. No clinical characteristics were significantly associated with residual PE at MDCT. LPS detected residual PE in 28% (26/93, 95% CI 19–38%) of patients after a period of a mean of 9 months of anticoagulation with a significant association with increasing age and known pulmonary disease. Resolution of PE was high after a first episode of non high-risk PE treated with heparin followed by at least 3 months of anticoagulation. Age and coexistent pulmonary disease influence the presence of residual PE detected by LPS, but not by MDCT. Further studies are warranted in which the presence of residual embolism is detected by repetition of the same test that had been initially carried out.     

Ventilation/perfusion lung scan in pulmonary veno-occlusive disease

Pulmonary veno-occlusive disease (PVOD), a rare form of pulmonary arterial hypertension (PAH), requires histological proof for definitive diagnosis; however, lung biopsy is not recommended in PAH. Recent conjoint European Respiratory Society/European Society of Cardiology guidelines suggest that nonmatched perfusion defects on ventilation/perfusion (V'/Q') lung scanning in PAH patients may suggest PVOD. The aim of our study was to evaluate V'/Q' lung scans in a large cohort of PVOD and idiopathic or heritable PAH patients. V'/Q' lung scans from 70 patients with idiopathic or heritable PAH and 56 patients with confirmed or highly probable PVOD were reviewed in a double-blind manner. The vast majority of V'/Q' lung scans were normal or without significant abnormalities in both groups. No differences in ventilation or perfusion lung scans were observed between PAH and PVOD patients (all p>0.05). Furthermore, no differences were observed between confirmed (n=31) or highly probable PVOD (n=25). Nonmatched perfusion defects were found in seven (10%) idiopathic PAH patients and four (7.1%) PVOD patients (p>0.05). Nonmatched perfusion defects were rarely seen in a large cohort of idiopathic or heritable PAH and PVOD patients. Future recommendations should be amended according to these results suggesting that V'/Q' lung scanning is not useful in discriminating PVOD from idiopathic PAH.     

Frequency of pulmonary embolism in patients with low-probability lung scan and negative lower extremity venous ultrasound

STUDY OBJECTIVES: To define the prevalence of pulmonary embolism (PE) in patients who are undergoing pulmonary arteriography because of a high clinical suspicion for PE but who have had a low-probability lung scan and a negative lower extremity venous ultrasound examination. DESIGN: A retrospective review of the medical records of 365 consecutive patients who underwent pulmonary arteriograms for suspected PE was undertaken. RESULTS: Of the 365 pulmonary arteriograms, 62 were performed in patients with suspected PEs despite a low-probability lung scan and a negative lower extremity venous ultrasound examination. In the latter group, five patients (8%; 95% confidence interval, 2.7% to 18%) had PEs revealed on the arteriogram. CONCLUSIONS: In patients whose presentation provokes a high clinical suspicion for PE despite having had a low-probability lung scan, a negative lower extremity venous ultrasound examination is insufficient to preclude proceeding to pulmonary angiography.     

320排螺旋CT肺动脉造影与核素肺通气灌注扫描评价肺动脉栓塞的对照研究

目的探讨以核素肺通气灌注扫描为参照,评价320排螺旋CT肺动脉造影诊断肺动脉栓塞的临床价值。方法 23例可疑PE患者为研究对象,分别采用核素肺通气灌注扫描和320排螺旋CT肺动脉造影进行检测,并以核素肺通气灌注扫描为诊断标准,评估320排螺旋CT肺动脉造诊断肺动脉栓塞临床价值。结果 23例患者460个有效肺段中核素肺通气灌注扫描显示128个肺段出现V/Q失衡,320排螺旋CT肺动脉造影显示124个肺段动脉血管充盈缺损。以NLVPS为参考,320排螺旋CT肺动脉造影诊断肺动脉栓塞的敏感性为0.95(95%CI:0.89-0.98),特异性为0.96(95%CI:0.94-0.98),阳性似然比为26.33(95%CI:14.71-47.12),阴性似然比为0.06(95%CI:0.03-0.11),诊断优势比为475.06(95%CI:179.99-1253.91)和受试者工作特征曲线下面积为0.98。结论 320排螺旋CT肺动脉造影可作为肺动脉栓塞的无创快速诊断方法。     

CT肺栓塞指数在肺栓塞患者中的临床应用研究

目的:探讨肺栓塞指数(CTI)在肺栓塞(PE)患者中的临床应用价值。方法:入选通过双源CT肺动脉造影确诊的187例PE患者,132例为急性PE,55例为慢性PE;急性PE中,低危组46例,中危组86例,高危组0例。通过CT影像计算CTI,结合PE危险分层绘制两者的受试者工作曲线(ROC曲线)并得到最佳诊断阈值,按对应的CTI将急、慢性PE患者分别划分为2组,对比分析2组的临床病例资料。结果:1急性PE中,低危组平均CTI为(37.5±27.4)%,中危组平均CTI为(50.8±23.9)%,差异具有统计学意义(P0.05);慢性PE平均CTI为(23.1±21.9)%。2CTI与危险分层的ROC曲线下面积为0.653(P=0.004),最佳诊断阈值对应的CTI为60%。3急、慢性PE患者CTI在性别、年龄分布上的差异均无统计学意义。4急性PE中,与CTI60%组相比,CTI≥60%组出现呼吸困难及晕厥症状比例更多,心率更快,PaO_2、SaO_2、PaCO_2降低,P(A-a)O_2增高,WBC、NEUT、Hs CRP增高,cTnI、BNP、D-二聚体增高,RA、RV、RV/LV增高(均P0.05)。2组在收缩压、舒张压方面差异无统计学意义。5慢性PE中,与CTI60%组相比,CTI≥60%组出现呼吸困难症状比例更多,PaO_2、SaO_2、PaCO_2降低,P(A-a)O_2增高,HsCRP、D-二聚体增高,RA、RV、RV/LV增高。急性、慢性PE中,CTI≥60%组的肺栓塞严重指数(PESI)评分均高于CTI60%组(P0.05)。结论:CTI与PE危险分层具有显著的相关性,两者ROC曲线的最佳诊断阈值所对应的CTI为60%。以60%为界,CTI可良好区分急、慢性PE患者的病情严重程度及预后,说明CTI在急、慢性PE患者中均具有一定的临床应用价值。     

Clinical outcome of patients with suspected pulmonary embolism. A follow-up study of 588 consecutive patients

OBJECTIVE: To investigate the clinical outcome in patients with clinically suspected pulmonary embolism (PE). Design and setting. In a retrospective design we studied 588 consecutive patients with suspected PE and referred for lung scintigraphy from 1995 to 1998. The mean follow-up time was 653 +/- 424 days. RESULTS: The diagnosis of PE was confirmed in 194 and excluded in 394 patients, respectively. The overall prevalence of PE was 33%. Amongst clinical and paraclinical variables, age, chronic obstructive pulmonary disease (COPD), heart rate, pleuritic pain, presence of deep venous thrombosis (DVT), electrocardiographic signs of right ventricular (RV) strain were identified as independent predictors of the diagnosis of PE. Amongst patients with PE anticoagulation was given in 96% for at least 3 months and 13% received thrombolytic therapy. Recurrent PE was seen in 6% of patients with PE whereas none of the patients with no diagnosis of PE suffered PE during follow-up. The 1 year mortality was 18% amongst patients with PE and 15% in patients with excluded PE (P=NS). The cause of death amongst patients with PE was cancer (49%) and PE (28%), whereas patients without PE had an excess mortality because of cancer, COPD, acute myocardial infarction and heart failure. CONCLUSION: Patients admitted to hospital on suspicion of PE have increased risk of adverse clinical outcome whether the diagnosis of PE is confirmed or not. This indicates that the patients where the diagnosis is excluded often suffer from other serious illness that warrants further investigations.