|Year : 2017 | Volume
| Issue : 1 | Page : 2-5
Clinical questions - Responses to queries from readers: Pulmonary Embolism
Dinesh Prabhu, Balamugesh Thangakunam
Department of Pulmonary Medicine, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Web Publication||17-Feb-2017|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Prabhu D, Thangakunam B. Clinical questions - Responses to queries from readers: Pulmonary Embolism. Curr Med Issues 2017;15:2-5
| Question 1|| |
How does one suspect pulmonary embolism in a peripheral setup and what is the management and prevention in a bedridden elderly patient?
The true incidence of pulmonary embolism (PE) is likely to be much higher than the reported number since many cases remain undiagnosed. About 10% cases die within the 1st h of diagnosis.
Mortality in treated patients is 2.5%–10% and in untreated patients increases to 30%.
| When to Suspect Pulmonary Embolism?|| |
- The mainstay for the diagnosis of PE is a high index of suspicion tempered by the reality that most patients with embolism have one or more factors predisposing to the condition
- The diagnosis of PE should be suspected in high-risk patients [Table 1]with respiratory symptoms unexplained by an alternative diagnosis [Table 2]
- Clinical features:
The most common presenting symptom of acute PE is sudden-onset dyspnea. Other symptoms include pleuritic chest pain, cough, leg swelling or pain, and hemoptysis
The most common physical finding is unexplained tachypnea (respiratory rate >20/min) present in approximately 70% of patients with embolism. Less frequent physical findings include rales, tachycardia, and increased pulmonic component of the second heart sound
The peripheral signs of deep venous thrombosis include unilateral lower limb swelling with tenderness, warmth, and nonpitting edema
- Clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being considered.
| The Role of Investigations|| |
Computed tomography pulmonary angiography (CTPA) is the diagnostic test for PE. Ventilation-perfusion scan (V/Q scan) is considered only when CTPA is not available or contraindicated.
The chest X-ray findings are usually nonspecific. Common findings include atelectasis, pleural effusion, pulmonary infiltrates, and mild elevation of a hemidiaphragm. Classic findings of pulmonary infarction such as Hampton's hump or decreased vascularity (Watermark's sign) are suggestive but infrequent.
The electrocardiogram (ECG) is nonspecific in the diagnosis of PE. The greatest utility of the ECG in a patient with suspected PE is ruling out other potential life-threatening diagnoses such as myocardial infarction and pericarditis. The S1Q3T3 pattern, commonly considered to be specific for PE, is seen only in a minority of patients.
Routine laboratory testing is not useful in confirming or excluding the diagnosis of PE but may be helpful in suggesting other diagnoses. Common findings include leukocytosis, hypoxemia, widening of the (A-a) gradient, and respiratory alkalosis.
D-dimer testing has proven to be highly sensitive but not specific. Increased levels are present in nearly all patients with thromboembolism but also occur in a wide range of other circumstances, including advancing age, pregnancy, trauma, infections, postoperative period, inflammatory states, and malignancy.
Cardiac troponins and natriuretic peptides can be elevated in acute PE. These are sensitive but nonspecific markers of myocardial inflammation or injury. The stretching of right ventricle (RV) from pressure overload found with massive or submassive PE may cause the release of troponins.
Echocardiography in acute PE may show RV enlargement, RV dysfunction, RV hypokinesia, and thrombus within the right side chambers, signs of pulmonary hypertension, etc.
Color Doppler of the lower limbs is used to look for deep vein thrombosis (DVT) in patients with clinical signs of DVT.
| Approach to Diagnosis|| |
- The algorithm recommended by the American College of Physicians (2016 clinical guideline) given in [Figure 1] is recommended in the approach to diagnosis of PE
- Clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being considered. The Modified Wells score is used to assess the pretest probability of PE [Table 3]
- In patients believed to be at low risk for PE (as assessed by Modified Wells score), the PE rule-out criteria (PERC) should be applied [Table 3]. In those who meet all 8 PERC criteria (i.e., score 0), the risk for PE is lower than the risks of testing and do not order a plasma D-dimer test. Those who do not meet all of the criteria should be further stratified using a plasma D-dimer test [Figure 1]
- In patients believed to be at medium or high risk for PE (as assessed by Modified Wells score), further investigation is required [Figure 1].
In resource-limited settings
In a resource-limited setting, a reasonable diagnosis of pulmonary embolism can be made and treatment can be initiated with low-molecular-weight heparin (LMWH) in the following clinical scenarios.
|Figure 1: Approach to diagnosis of pulmonary embolism (based on the American College of Physicians 2016 clinical guideline).|
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Patient with symptoms suspicious of pulmonary embolism as mentioned above with one or more of the following:
- Chest X-ray showing no abnormality
- ECG showing no features of acute myocardial infarction
- Ultrasonography Doppler of the lower limb(s) showing deep venous thrombosis
- ECHO showing right atrium/RV dilatation, RV dysfunction, pulmonary hypertension in a patient with no such previous findings
- Patients with no previous cardiopulmonary disease.
In such scenarios, a provisional diagnosis of pulmonary embolism can be made and treatment can be initiated (LMWH). The patient may then be referred to a center where there is provision for CTPA for confirmation of diagnosis.
| Pulmonary Embolism in Elderly|| |
Some features that characteristic of PE in the elderly population are enlisted below:
- PE diagnosis in elderly people is difficult because many cardiopulmonary conditions may mimic clinical presentation of PE, and age may unfavorably influence the characteristics of diagnostic tests for PE. Clinicians should use age-adjusted D-dimer thresholds (age ×10 ng/mL rather than a generic 500 ng/mL) in patients older than 50 years to determine whether imaging is warranted
- The rate of inconclusive ventilation-perfusion lung scans is almost twice as high (58%) in patients older than 70 and patients younger than 40 (32%)
- There is a high risk of bleeding in elderly patients
- Aging, however, does not change the diagnostic accuracy of clinical probability assessment whether empirical or as determined by prediction rules.
| Management of Pulmonary Embolism|| |
In an established case of PE, the patient needs to be initiated on anticoagulation ,
LMWH overlapped with oral warfarin to maintain an international normalized ratio (INR) of 2–3. LMWH can be stopped when INR reaches >2.
Newer oral anticoagulants (dabigatran, rivaroxaban, etc.,) which do not require monitoring of INR are also available and can be used.
| Pulmonary Embolism Prophylaxis|| |
Elderly patients who are hospitalized are advised to receive thromboprophylaxis using either pharmacological or nonpharmacological measures.
Pharmacological measures include unfractionated heparin 5000 units subcutaneously twice daily or LMWH 40 units subcutaneous once daily. Nonpharmacological measures include compression stockings for lower limbs. Early mobilization is recommended for all bedridden and postoperative patients.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
Raja AS, Greenberg JO, Qaseem A, Denberg TD, Fitterman N, Schuur JD; Clinical Guidelines Committee of the American College of Physicians. Evaluation of patients with suspected acute pulmonary embolism: Best practice advice from the Clinical Guidelines Committee of the American College of Physicians. Ann Intern Med 2015;163:701-11.
Konstantinides SV, Torbicki A, Agnelli G, Danchin N, Fitzmaurice D, Galiè N, et al.
2014 ESC guidelines on the diagnosis and management of acute pulmonary embolism. Eur Heart J 2014;35(43):3033-69, 3069a-3069k.
Kearon C, Akl EA, Ornelas J, Blaivas A, Jimenez D, Bounameaux H, et al.
Antithrombotic therapy for VTE disease: CHEST guideline and expert panel report. Chest 2016;149:315-52.
[Table 1], [Table 2], [Table 3]