心电图在急性肺栓塞诊断中的应用价值研究

目的：分析心电图在急性肺栓塞诊断中的应用价值。方法抽取我院收治的临床确诊为急性肺栓塞患者54例,对其临床表现及心电图检查结果进行统计分析。结果本组54例患者发生心电图改变52例,包括窦性心动过速40例,室上性心动过速2例,房性早搏38例,TV1～TV3同时出现倒置17例,出现 SⅠQⅢTⅢ9例,右束支传导阻滞12例。结论急性肺栓塞患者会出现明显的心电图改变,掌握心电图变化特点对于急性肺栓塞的诊断具有重要意义,值得推广应用。     

心电图与D-二聚体在急性肺栓塞患者的诊断价值

目的探讨心电图与D-二聚体在急性肺栓塞患者的诊断价值。方法选择在我院接受诊治的经肺动脉血管造影检查确诊为急性肺栓塞患者58例作为研究对象,另外选取同期在我院治疗的经X线及细菌学检查确诊为慢性支气管炎患者53例作为对照组,所有患者均接受心电图、D-二聚体诊断,探讨心电图、D-二聚体对急性肺栓塞患者诊断价值。结果心电图检测对急性肺栓塞患者检测阳性率为93.10%,显著高于对慢性支气管炎检测阳性率(P0.05);D-二聚体检测对急性肺栓塞患者检测阳性率为89.66%,显著高于对慢性支气管炎检测阳性率(P0.05)。结论心电图与D-二聚体在急性肺栓塞诊断中均具有重要的诊断价值。     

Diagnostic methods in pulmonary embolism

Diagnosing pulmonary embolism (PE) is challenging since clinical signs and symptoms are non-specific. The diagnostic tests available for demonstrating PE all have their drawbacks and are often costly and consume considerable amounts of resources. Simple tools that have become available in the last several years include clinical prediction rules and D-dimer testing. Assessment of the clinical probability, combined with a D-dimer test, can limit the need for additional diagnostic tests by 30%. For outpatients with a normal, sensitive ELISA D-dimer test and a low-to-moderate clinical probability, PE can safely be ruled out. Pulmonary angiography, though still the gold standard, is rarely used nowadays because of its invasiveness, its high costs and limited availability, and the declining experience of radiologists with the technique. Two imaging techniques--lung scintigraphy and helical CT--are the diagnostic methods of choice. A normal perfusion lung scan can safely exclude PE. However, 55-65% of patients have indeterminate lung scan results, making additional imaging tests necessary. Helical CT is increasingly being used as the first-line test because it can directly visualize a thromboembolus, it can suggest an alternative diagnosis, and there is excellent inter-observer agreement. A normal helical CT, followed by compression ultrasonography of the leg veins, can safely rule out PE. Finally, the safety of withholding anticoagulant treatment from patients with a normal multi-row detector helical CT as the sole test has not yet been demonstrated.     

肺栓塞的诊断进展

肺动脉栓塞(pulmonary embolism，PE)是内源性或外源性栓子堵塞肺动脉引起肺循环障碍的临床和病理生理综合征，其中肺血栓栓塞症(pulmonary thromboemlism，PTE)是最常见的一种类型。PTE发病率、误诊率、致死率和致残率高，目前已成为重要的医疗保健问题。PTE误、漏诊的主要原因是医师对该病的认识不足和(或)诊断技术应用不当。     

Clinical, laboratory, roentgenographic, and electrocardiographic findings in patients with acute pulmonary embolism and no pre-existing cardiac or pulmonary disease

The history, physical examination, chest radiograph, electrocardiogram and blood gases were evaluated in patients with suspected acute pulmonary embolism (PE) and no history or evidence of pre-existing cardiac or pulmonary disease. The investigation focused upon patients with no previous cardiac or pulmonary disease in order to evaluate the clinical characteristics that were due only to PE. Acute PE was present in 117 patients and PE was excluded in 248 patients. Among the patients with PE, dyspnea or tachypnea (greater than or equal to 20/min) was present in 105 of 117 (90 percent). Dyspnea, hemoptysis, or pleuritic pain was present in 107 of 117 (91 percent). The partial pressure of oxygen in arterial blood on room air was less than 80 mm Hg in 65 of 88 (74 percent). The alveolar-arterial oxygen gradient was greater than 20 mm Hg in 76 of 88 (86 percent). The chest radiograph was abnormal in 98 of 117 (84 percent). Atelectasis and/or pulmonary parenchymal abnormalities were most common, 79 of 117 (68 percent). Nonspecific ST segment or T wave change was the most common electrocardiographic abnormality, in 44 of 89 (49 percent). Dyspnea, tachypnea, or signs of deep venous thrombosis was present in 107 of 117 (91 percent). Dyspnea or tachypnea or pleuritic pain was present in 113 of 117 (97 percent). Dyspnea or tachypnea or pleuritic pain was present in 113 of 117 (97 percent). Dyspnea or tachypnea or pleuritic pain or atelectasis or a parenchymal abnormality on the chest radiograph was present in 115 of 117 (98 percent). In conclusion, among the patients with pulmonary embolism that were identified, only a small percentage did not have these important manifestations or combinations of manifestations. Clinical evaluation, though nonspecific, is of considerable value in the selection of patients in whom there is a need for further diagnostic studies.     

Diagnostic imaging and risk stratification of patients with acute pulmonary embolism

Pulmonary embolism (PE) is the third most common acute cardiovascular disease after myocardial infarction and stroke. The prompt diagnosis, risk stratification, and treatment of patients with acute PE can reduce mortality. Multidetector row computed tomography pulmonary angiography (CTPA) is the most common study used to make the diagnosis of acute PE. CTPA may additionally identify right heart dysfunction or alternative diagnoses. There is a growing body of evidence that computed tomography signs of right heart failure predict patients at higher risk of mortality. At the same time, CTPA has about a 6-fold greater whole body effective dose than ventilation-perfusion (V/Q) scintigraphy, and a much higher dose to breast tissue in particular. V/Q scintigraphy should be considered for patients with contraindications to iodinated contrast or for patients with normal chest radiographs, especially young women. Compression ultrasonography of the proximal lower extremities, an imaging study without ionizing radiation, should be considered for patients suspected of acute PE with signs of lower extremity deep venous thrombosis or for patients with negative CTPA or V/Q scan with discordant clinical probability. This article reviews factors affecting the selection of the best imaging test for a particular patient suspected of acute PE, performance characteristics of diagnostic imaging tests, and imaging findings that correlate with higher mortality.     

Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II investigators

Purpose

To formulate comprehensive recommendations for the diagnostic approach to patients with suspected pulmonary embolism, based on randomized trials.

Methods

Diagnostic management recommendations were formulated based on results of the Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) and outcome studies.

Results

The PIOPED II investigators recommend stratification of all patients with suspected pulmonary embolism according to an objective clinical probability assessment. D-dimer should be measured by the quantitative rapid enzyme-linked immunosorbent assay (ELISA), and the combination of a negative D-dimer with a low or moderate clinical probability can safely exclude pulmonary embolism in many patients. If pulmonary embolism is not excluded, contrast-enhanced computed tomographic pulmonary angiography (CT angiography) in combination with venous phase imaging (CT venography), is recommended by most PIOPED II investigators, although CT angiography plus clinical assessment is an option. In pregnant women, ventilation/perfusion scans are recommended by many as the first imaging test following D-dimer and perhaps venous ultrasound. In patients with discordant findings of clinical assessment and CT angiograms or CT angiogram/CT venogram, further evaluation may be necessary.

Conclusion

The sequence for diagnostic test in patients with suspected pulmonary embolism depends on the clinical circumstances.     

Hypoxemia in acute pulmonary embolism

Most patients with severe, acute pulmonary embolism (PE) have arterial hypoxemia. To further define the respective roles of ventilation to perfusion (VA/Q) mismatch and intrapulmonary shunt in the mechanism of hypoxemia, we used both right heart catheterization and the six inert gas elimination technique in seven patients with severe, acute PE (mean vascular obstruction, 55 percent) and hypoxemia (mean PaO2, 67 +/- 11 mm Hg). None had previous cardiopulmonary disease, and all were studied within the first ten days of initial symptoms. Increased calculated venous admixture (mean QVA/QT 16.6 +/- 5.1 percent) was present in all patients. The relative contributions of VA/Q mismatching and shunt to this venous admixture varied, however, according to pulmonary radiographic abnormalities and the time elapsed from initial symptoms to the gas exchange study. Although all patients had some degree of VA/Q mismatch, the two patients studied early (ie, less than 48 hours following acute PE) had normal chest x-ray film findings and no significant shunt; VA/Q mismatching accounted for most of the hypoxemia. In the others a shunt (3 to 17 percent of cardiac output) was recorded along with radiographic evidence of atelectasis or infiltrates and accounted for most of the venous admixture in one. In all patients, a low mixed venous oxygen tension (27 +/- 5 mm Hg) additionally contributed to the hypoxemia. Our findings suggest that the initial hypoxemia of acute PE is caused by an altered distribution of ventilation to perfusion. Intrapulmonary shunting contributes significantly to hypoxemia only when atelectasis or another cause of lung volume loss develops.     

Fever in acute pulmonary embolism

BACKGROUND: Although fever has been reported in several case series of acute pulmonary embolism (PE), the extent to which fever may be caused by PE, and not associated disease, has not been adequately sorted out. Clarification of the frequency and severity of fever in acute PE may assist in achieving an accurate clinical impression, and perhaps avoid an inadvertent exclusion of the diagnosis. PURPOSE: The purpose of this investigation is to evaluate the extent to which fever is caused by acute PE. METHODS: Patients participated in the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). Temperature was evaluated among patients with angiographically proven PE. A determination of whether other causes of fever were present was based on a retrospective analysis of discharge summaries, PIOPED summaries, and a computerized list of all discharge diagnoses. RESULTS: Among patients with PE and no other source of fever, fever was present in 43 of 311 patients (14%). Fever in patients with pulmonary hemorrhage or infarction was not more frequent than among those with no pulmonary hemorrhage or infarction, 39 of 267 patients (15%) vs 4 of 44 patients (9%; not significant). Clinical evidence of deep venous thrombosis was often present in patients with PE and otherwise unexplained fever. CONCLUSION: Low-grade fever is not uncommon in PE, and high fever, although rare, may occur. Fever need not be accompanied by pulmonary hemorrhage or infarction.     

Diagnosing pulmonary embolism using clinical findings

To determine the value of clinical findings in the diagnosis of pulmonary embolism, we analyzed the records of 82 patients from three different hospitals who underwent pulmonary arteriography to rule out pulmonary embolism. We recorded 92 items of clinical information, including lung ventilation-perfusion scan results, for each patient. Although the diagnostic power of any single variable was marginal, an eight-item decision rule derived using discriminant analysis correctly predicted the outcome of arteriography in 82% of the cases. When tested on a different group of 68 patients from four hospitals, the rule accurately identified patients with low or high likelihood of having positive arteriograms. Clinical use of such a rule could reduce the need for arteriography in this population and would expedite decisions about anticoagulant therapy and further diagnostic testing.