|Year : 2018 | Volume
| Issue : 1 | Page : 6-12
Different modalities in diagnosis of thrombotic pulmonary embolism: a hospital-based study
Ibrahim M Shalan1, Hosni A Younis2, Haitham A Azeem2, Mohamed Mahmoud3, Saad R Abdulwahed Hussein4
1 Department of Chest Diseases, Faculty of Medicine (Assiut), Al-Azhar University, Cairo, Egypt
2 Department of Internal Medicine, Faculty of Medicine (Assiut), Al-Azhar University, Cairo, Egypt
3 Department of Cardiology, Faculty of Medicine (Assiut), Al-Azhar University, Cairo, Egypt
4 Department of Radiology, Faculty of Medicine (Assiut), Al-Azhar University, Cairo, Egypt
|Date of Submission||03-Jan-2017|
|Date of Acceptance||03-Dec-2017|
|Date of Web Publication||20-Nov-2018|
Ibrahim M Shalan
Department of Chest Diseases, Al-Azhar University, Faculty of Medicine (Assiut), Cairo
Source of Support: None, Conflict of Interest: None
Background Pulmonary embolism (PE) is a potentially life-threatening cardiovascular emergency with a high mortality rate; PE is a difficult diagnosis that may be missed because of nonspecific clinical presentation. However, multidetector computed tomography pulmonary angiography (MDCT-PA) is considered the gold standard in diagnosis. D-Dimer has high sensitivity to PE that if negative and clinical probability is low PE can safely be excluded without the need for further investigation.
Objective The aim of this study was to evaluate demographic data, clinical, radiographic, and laboratory findings in patients with PE and the relationship of those findings with the embolism location, and the reason for severity of the embolism.
Patients and methods This study was conducted on 100 patients diagnosed with PE based on MDCT-PA at Chest Diseases Department of Al-Azhar Assiut and Assiut University Hospitals, Egypt, from May 2013 to December 2015. All patients were subjected to complete history taking, clinical examination, routine investigations, D-dimer, O2 saturation, arterial blood gases, ECG, Doppler ultrasound, chest radiography, MDCT-PA for all patients, and echocardiography in selected patients.
Results There were significant differences between D-dimer from one hand and severity of PE, and also the site and extent of the embolus from the other hand, as D-dimer levels were higher in massive than submassive PE, and in main pulmonary artery embolus than segmental branches, and lastly subsegmental branches. ECG findings in PE were nonspecific but could aid in the diagnosis. The most common findings were sinus tachycardia followed by inverted T wave in anterior chest leads, whereas the typical S1Q3T3 was less common.
Conclusion A practical and evidence-based approach is to combine a D-dimer result with a validated clinical risk score to help selection of suitable patients for computed tomography pulmonary angiogram.
Recommendation A clinical probability assessment and D-dimer value should be combined and used to quantify the patient’s risk of PE as low, moderate, or high.
Keywords: D-dimer, multidetector computed tomography pulmonary angiography, pulmonary embolism
|How to cite this article:|
Shalan IM, Younis HA, Azeem HA, Mahmoud M, Abdulwahed Hussein SR. Different modalities in diagnosis of thrombotic pulmonary embolism: a hospital-based study. Al-Azhar Assiut Med J 2018;16:6-12
|How to cite this URL:|
Shalan IM, Younis HA, Azeem HA, Mahmoud M, Abdulwahed Hussein SR. Different modalities in diagnosis of thrombotic pulmonary embolism: a hospital-based study. Al-Azhar Assiut Med J [serial online] 2018 [cited 2019 Oct 19];16:6-12. Available from: http://www.azmj.eg.net/text.asp?2018/16/1/6/244142
| Introduction|| |
Pulmonary embolism (PE) is a potential cardiovascular emergency and occurs when a part of a thrombus, usually dislodged from a deep vein thrombosis (DVT), passes into the pulmonary circulation, occluding the pulmonary arteries (thrombotic type) . PE is a potentially life-threatening cardiovascular emergency with a high mortality rate. Rapid diagnosis and treatment are important in optimizing clinical outcomes in patients with PE, and anticoagulants are the mainstay of management . Between 1979 and 1988, deaths from PE decreased by 30%. This change is likely due to a combination of factors including changes in diagnostic patterns, decreased incidence of PE, and decreased case fatality rate ,. There are more than 650 000 cases of PE that occur each year in USA, resulting in as many as 300 000 fatalities per year and ranking PE as the third leading cause of death . Computed tomography (CT) pulmonary angiogram is a relatively safe, noninvasive test that can be performed quickly in an emergency setting to identify directly the presence and extent of PE. CT has also been found to be cost-effective in various diagnostic algorithms .
| Patients and methods|| |
This study was carried out on 100 patients (56 female and 44 male), aged 22–86 years, and the mean age was 50.8+14.5 years. The study was approved by local ethical committee of Assuit Faculty of medicine, Al-Azhar University to evaluate and publish information gained data. Patients were recruited from the emergency room and admitted at Chest Department of Al-Azhar Assiut and Assiut University Hospitals in the period from May 2012 to December 2014. Informed and written consent was taken.
Each patient was subjected to the following:
- Complete history taking included the following:
- Personal history: A questionnaire was completed for each patient. Name, age, sex, marital state, occupation and special habits (smoking, alcohol, and drug abuse), and respiratory questions were asked about previous pulmonary or systemic diseases, cough, dyspnea, chest pain, fever, hemoptysis, and risk factors for DVT such as respiratory, cardiac, renal, or systemic diseases.
- Family history: DVT or PE.
- Past history: DVT, PE or any other associated disease.
- Physical examinations.
- Laboratory and immunologic investigations:
- Complete blood count, erythrocyte sedimentation rate, C-reactive protein, blood sugar analysis, arterial blood gases (ABG), renal function tests (urea, creatinine), liver function tests (alanine aminotransaminase, aspartate aminotransaminase, bilirubin), and D-dimer assay were peformed. (Enzyme-linked immunosorbent assay is considered the gold standard for the determination of D-dimer concentration. It is a highly sensitive test but is time-consuming and not suitable for individual patient testing.) The Accuclot D-dimer assay is less sensitive, but suitable for individual patient testing . The Trinity Amax Accuclot D-dimer e Triage MeterPLus (San Diego, California) assay is a semiquantitative latex agglutination assay that was used during the study period.
- ECG: It was performed by the use of a standard 12-lead ECG using the Fukuda apparatus.
- Oxygen saturation: It was performed by the finger method and ABG.
- Imaging studies included the following:
- Chest radiography: both PA and lateral views were taken. The chest radiographic finding is nonspecific but can aid in diagnosis and help in exclusion of other diseases.
- Doppler examination of the lower extremities was used for determining DVT of the lower limbs by using the Mindray apparatus.
- Echocardiography: for selected patients with bad general condition, emergency, multidetector computed tomography pulmonary angiography (MDCT-PA) was unavailable, or suspected other disease
- MDCT-PA: it is considered as the gold standard for diagnosis of PE.
Technique for MDCT-PA is as follows: (i) − Patient preparation is done in the form of good hydration and wide-bore cannula in the peripheral veins. (ii) The protocol of MDCT-PA was performed with a hi-speed advantage scanner (GE Medical Systems, Milwaukee, Wisconsin, USA), with four detector arrays. Patients were scanned from the lower lobes to the apices during a single breath-hold technique. Retrograde acquisition was chosen to minimize artifacts from high-contrast material concentration in the superior vena cava. The entire thorax was included in the CT acquisitions. Patients who were unable to hold their breath were asked to breathe as shallowly as possible during the acquisition. The time interval between application of contrast material and the start of data acquisition, the scan delay, should be chosen according to the patient’s clinical status. In patients who have no history, signs, or symptoms of pulmonary arterial hypertension, right ventricular failure, or overall cardiac failure, a scan delay ranging from 15 to 20 s is sufficient to allow for optimum vessel opacification. In patients with signs or symptoms of any of the aforementioned disorders, a scan delay ranged from 20 to 30 s may be necessary and should be determined by the smart prep technique − that is, an automatically triggered contrast media injection. Patients in whom contrast medium injection is contraindicated as severe renal failure and with known hypersensitivity to contrast material were excluded from the study.
The patients were classified according to severity of PE into massive and submassive according to American Heart Association guidelines .
- Massive PE − Acute PE with sustained hypotension [systolic blood pressure (SBP)<90 mmHg for at least 15 min or requiring inotropic support, not due to a cause other than PE, such as arrhythmia, hypovolemia, sepsis, or left ventricular dysfunction], pulselessness, or persistent profound bradycardia (heart rate<40 bpm with signs or symptoms of shock).
- Submassive PE − Acute PE without systemic hypotension (SBP>90 mmHg) but with either right ventricular dysfunction or myocardial necrosis.
Data analysis was done using SPSS for Windows, version 11.0 (SPSS Inc., Chicago, Illinois, USA), statistical package. Descriptive statistics were shown as mean±SD. Univariate analysis was performed using χ2-test. To compare parametric values of massive and submassive PE, χ2 testing followed by Fisher’s exact test with the use of the permutation method for multiple testing was performed. P value less than 0.05 was considered statistically significant.
| Results|| |
The study was carried out during the period from May 2012 to December 2014, on 100 patients diagnosed with PE based on MDCT-PA in the Chest Department of Al-Azhar Assiut and Assiut University Hospitals.
This study included 44 (44%) men and 56 (56%) women. Ages ranged from 22 to 86 years old with a mean age of 50.8±14.5 years; of them, 34 (34%) were smokers and 66 (66%) were nonsmokers. The most common presenting symptoms was dyspnea in 90 (90.0%) patients followed by cough in 66 (66.0%) patients, chest pain in 58 (58.0%) patients, hemoptysis in 52 (52.0%) patients, and fever in 40 (40.0%) patients. This study demonstrated that the incidence of PE was more common in old age with a mean age of 50.8+14.5 years, without significant difference. In addition, the incidence of PE was slightly higher in women than in men, 56 and 44%, respectively, without significant difference.
There were no statistically significant differences between severity of PE (massive and submassive) and gender (P=0.477), smoking (P=0.318), and clinical symptoms such as dyspnea (P=0.160), cough (P=0.629), chest pain (P=0.739), hemoptysis (P=0.568), and fever (P=0.967) ([Table 1] and [Figure 1]).
|Table 1 Relation between demographic data and clinical symptoms and severity of pulmonary embolism|
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|Figure 1 Relation between the clinical symptoms and severity of pulmonary embolism.|
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The laboratory findings showed no statistically difference between severity of PE (massive and submassive) and leukocytosis (P=0.799), low hemoglobin (P=0.891), elevated bilirubin (P=0.529), low albumin (P=0.481), elevated liver enzymes (P =0.880), elevated urea (P=0.569), elevated creatinine (P=0.062), or elevated blood sugar (P=0.979) ([Table 2]).
|Table 2 Relation between laboratory findings and severity of pulmonary embolism|
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There were statistically significant differences between severity of PE (massive and submassive) and hemodynamic status of the patients regarding heart rate (P=0.008), SBP (P=0.002), and diastolic blood pressure (DBP) (P<0.000) ([Table 3]). Also there was a statistically significant difference between severity of PE (massive and submassive) and ABG finding as regards normal pH (P<0.001) and alkalosis (P<0.001), whereas there was no statistically significant difference regarding acidosis (P=0.727), O2 saturation (P=0.156), PaO2 (P=0.069), and PaCO2 (P=0.550) ([Table 3]).
|Table 3 Relation between hemodynamic status, blood gases, and severity of pulmonary embolism|
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Regarding radiographic findings, there were no statistically significant differences between severity of PE (massive and submassive) and the presence of pleural effusion (P=0.481), cardiomegaly (P=0.880), consolidation (P=0.737), raised copula (P=0.894), hyperinflation (P=0.532), or normal radiographic finding (P=0.854) ([Figure 2]).
|Figure 2 Relation between radiography finding and severity of pulmonary embolism.|
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Concerning the site and extent of the embolus, there were statistically significant differences between severity of PE (massive and submassive) and site of the vessel affected in the main pulmonary artery in 24 (44.4%) patients versus two (3.7%) patients (P<0.001), and subsegmental embolus in four (7.4%) patients versus 22 (40.7%) patients (P<0.001), whereas there was no statistically significant difference between them in segmental embolus (P=0.866), right-sided embolus (P<0.895), left-sided embolus (P=0.241), and bilateral embolism (P=0.346) ([Figure 3]).
|Figure 3 Relation between the extent of the embolus and severity of pulmonary embolism.|
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There were statistically significant differences between severity of PE (massive and submassive) and the ECG finding regarding sinus tachycardia, which was present in 42 (77.8%) patients versus 24 (52.2%) patients (P=0.013), T-wave inversion in anterior precordial leads in 12 (22.2%) patients versus two (4.3%) patients (P=0.022), and normal finding in no (0.00%) patient versus 16 (29.6%) patients (P<0.001), whereas there was no statistically significant difference regarding RBBB in eight (14.8%) patients versus eight (17.4%) patients (P=0.939) and S1Q3T3 in 14 (25.9%) patients versus 10 (18.5%) patients (P=0.799) ([Figure 4]).
There was a positive correlation between D-dimer level and extent of PE (main, segmental, and subsegmental) (4390±1859.2 µg/l) in main pulmonary artery embolus (2561.3±1386.2 µg/l) in segmental pulmonary artery embolus, and lastly (1856.9±1149.5 µg/l) in subsegmental pulmonary artery embolus (P<0.000). On the other hand, there was no statistically significant difference regarding the site of PE (right, left, bilateral) and D-dimer level (P=0.701); also, there was no statistically significant difference between the site of the embolus and O2 saturation (P=0.158), or between O2 saturation and the extent of the embolus (main, segmental and subsegmental) (P=0.958) ([Table 4] and [Table 5).
|Table 4 Relation of D-dimer and O2 saturation and severity of pulmonary embolism|
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|Table 5 Relation of D-dimer and O2 saturation and extent of pulmonary embolism|
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There was a negative correlation but statistically nonsignificant difference between D-dimer and O2 saturation in massive and submassive PE (r=−0.270, P=0.224 vs. r=−0.118, P=0.551) ([Figure 5] and [Figure 6]).
|Figure 5 Relation between O2 saturation and D-dimer in massive pulmonary embolism.|
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|Figure 6 Relation between O2 saturation and D-dimer in submassive pulmonary embolism.|
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| Discussion|| |
Clinical criteria for diagnosis of PE guidelines recommend that before any diagnostic tests are performed the clinical probability of acute PE should be assessed. Initial assessment of the probability of acute PE is strongly recommended ,. When the clinical probability and results of objective testing are discordant, the post-test probability of PE may be neither sufficiently high nor sufficiently low to permit therapeutic decisions . Under these circumstances, further objective testing is mandatory . The results of this study showed that the incidence of PE was slightly higher in women than in men, 56% and 44%, respectively, without significant difference. These results were in agreement with the finding reported by Stein et al. . The latter found that the rate of PE was higher in women than in men (60/100 000 women and 42/100 000 men). Concerning age, the results of this work showed that the incidence of PE was more common in old age with a mean age of 50.8+14.5 years, without significant difference. Dyspnea was the common presenting symptom, which occurred in 90% of patients, followed by cough, chest pain, and lastly hemoptysis (66, 58, and 52%, respectively). Manal and Raghda  found that dyspnea was the most common presenting symptom in 90.6%, followed by tachycardia in 81.2%, tachypnea in 76.6%, chest pain in 65.6%, and lastly hemoptysis in 12.5%. Stein and Matta  found chest pain in 66% and nonproductive cough in 37%, and also Pollack et al.  showed that dyspnea was the most common clinical presentation for PE. This study demonstrated that D-dimer level was very high (2853 µg/l) as compared with the laboratory normal range of 790 µg/l. It was significantly higher in massive than submassive PE. According to the site, D-dimer level was shooting in cases of obstruction to the main pulmonary artery. These results were in agreement with Coskun et al. , who found that the mean D-dimer levels of massive PE patients, as measured with the monoclonal antibody method, were significantly higher compared with those of nonmassive patients. In a study of 312 patients with documented PE, 35% had normal alveolar–arterial gradient, PaO2, and PaCO2, respectively .
Unfortunately, hospitalized patients often have disorders that cause a positive D-dimer test , and D-dimer is particularly likely to be elevated in patients in the coronary care unit. Exclusion of PE on the basis of a negative D-dimer and clinical assessment would be cost-effective. The charge for a D-dimer is about 1% the charge (including physician fees) for a CT angiogram, 3% the charge for a ventilation–perfusion scan, and about 4% the charge for a bilateral venous ultrasound . D-Dimer may be elevated in patients with unstable angina . Some observed elevations of D-dimer in patients with myocardial infarction , although others observed elevations of D-dimer infrequently among conventionally treated patients. Congestive heart failure also causes elevations of D-dimer . In our study, according to American Heart Association classification, 54 patients had massive PE with a mean SBP of 85.7 mmHg and DBP of 51 mmHg with signs of shock and persistent bradycardia (<40 bpm), whereas 46 patients had submassive PE with normal blood pressure but with ECG changes and echo changes. There was a statistically significant difference between massive and submassive PE regarding to SBP and DBP and heart rate. These results were in agreement with those of Coskun et al. , who found that there were significant differences in hemodynamic parameters such as mean heart rate, mean SBP, and mean DBP and heart rate between massive and submassive PE. In this study, chest pain was reported in 58% patients; in 24% of them, inverted T wave was observed. The most common ECG abnormality was sinus tachycardia (66%), followed by T-wave inversion in 24%, S1Q3T3 in 14%, and left bundle branch block in 16%, and T-wave inversion was significantly higher in massive than submassive PE. These results were in agreement with those of Ferrari et al. , who found that the T-wave inversion was significantly higher in massive than submassive PE . In patients with mild to massive PE, a normal ECG was shown in 30% . Atrial flutter or atrial fibrillation in patients with acute PE is infrequent in patients with no prior heart disease . Abnormalities of the ST-segment and T wave are by the most frequent ECG manifestation of PE ,. Stein et al.  concluded that ECG manifestations of acute corpulmonale (S1Q3T3, complete right bundle branch block, P pulmonale, or right axis deviation) occurred in 26–32% of patients with submassive or massive acute PE who did not have associated cardiac or pulmonary disease. Some of the nonspecific radiographic abnormalities combined with symptoms and ECG abnormalities may suggest that PE is present. The chest radiograph, in addition, is useful for the exclusion of conditions that mimic acute PE (pneumonia, pneumothorax, pleurisy) or to evaluate comorbid or predisposing conditions (heart failure), as well as to aid in the diagnostic interpretation of some imaging tests (pulmonary scintigraphy) . In this work, the most common radiography findings were consolidation in 32%, followed by effusion in 26% and no radiographic abnormality in 22%. Positive CT angiographic findings may be relied upon if the clinical impression indicates a high probability for PE (96% had PE) . If the CT angiogram/CT venogram combination is negative in a patient with a high-probability clinical assessment, the false negative rate is 18% and further evaluation is recommended by ventilation–perfusion scan, serial ultrasound, or conventional angiography. This study illustrated that the anatomical distribution of pulmonary emboli was more in segmental pulmonary artery (48%), main pulmonary artery (26%), and lastly subsegmental pulmonary artery (24%). These findings were comparable to those reported by Sohns et al. , who found that the majority of thrombi were diffusely distributed between the main pulmonary trunk (32%), lobar (30%), and segmental arteries (32%), with only a small minority involving the subsegmental vessels (6%). In addition, Manal and Raghda  found that the most common site of the emboli was in segmental arteries (32%) followed by main pulmonary (24%) and minority in subsegmental vessels (12%). In a study conducted in oncological patients with PE, Refaat and El-Shinnawy  found that the most common site of the emboli was in lobar pulmonary artery in 40%, followed by segmental pulmonary artery in 31%, subsegmental pulmonary artery in 16%, and lastly main pulmonary artery in 13%.
| Conclusion|| |
A practical and evidence-based approach is to combine D-dimer results with a validated clinical risk score to help selection of suitable patients for CT pulmonary angiogram. This may prevent patients from being exposed to unnecessary irradiation.
A clinical probability assessment and D-dimer value should be combined and used to quantify the patient’s risk of PE as low, moderate, or high.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]