Pulmonary Embolism
Pulmonary Embolism: Excerpt from The 5-Minute Pediatric Consult
Akinyemi O. Ajayi, MD
Pulmonary Embolism - BASICS
Pulmonary Embolism - description
- Occlusion of a pulmonary vessel by a thrombus
- Pitfalls:
- Failure to make the diagnosis is the most common mistake.
- Pulmonary embolism must be suspected in critically ill children who have a central venous catheter in place and subsequently develop sudden respiratory failure. Because the symptoms of severe lung disease and pulmonary embolism are similar, the diagnosis might be missed if the index of suspicion is low.
Pulmonary Embolism - epidemiology
- Pulmonary embolism is seen more frequently in adults and tends to occur in postsurgical situations, especially when patients have been bedridden.
- ~10% of adults who present with an acute pulmonary embolus die within 1 hour of onset.
- Death occurs with 85% obstruction of the pulmonary artery.
- Risk factors vary according to age groups and gender.
Pulmonary Embolism - incidence
- Pulmonary embolism is rarely recognized in children; the incidence in children is 3.7%.
- Increasing incidence is secondary to increased central catheter use.
- Mortality rate can be as high as 30% if diagnosis is delayed.
Pulmonary Embolism - risk factors
- In children:
- Presence of a central venous catheter
- Lack of mobility
- Congenital heart disease
- Ventriculoatrial shunt
- Trauma
- Solid tumors or leukemia
- After surgical procedures (especially reparative intervention for scoliosis repair)
- Hypercoagulable condition
- In adults: Most commonly due to the presence of a deep vein thrombosis, usually in the legs or pelvis.
Pulmonary Embolism - pathophysiology
- Thromboemboli may develop anywhere in the systemic venous system.
- Pulmonary embolism is characterized by the triad of hypoxemia, pulmonary hypertension, and right ventricular failure.
- Diminished pulmonary perfusion causes a ventilation/perfusion (VQ) mismatch, resulting in hypoxemia.
- Hyperventilation occurs secondary to stimulation of proprioceptors in the lung.
- Hypercapnia is seen with severe occlusion of the pulmonary artery (often not seen with smaller emboli).
- Pulmonary infarction is uncommon owing to the presence of collateral pulmonary and bronchial arteries along with the airways providing additional sources of oxygen to the tissues.
Pulmonary Embolism - etiology
Blood clots appear as a result of deep vein thrombosis or other disease states.
Pulmonary Embolism - DIAGNOSIS
Pulmonary Embolism - signs & symptoms
- Pulmonary embolism should be suspected in children who present with:
- Pleuritic chest pain
- Shortness of breath
- Hemoptysis
- Cough
- Acute respiratory distress
- Apprehension or anxiety
- Syncope
- Cardiovascular shock
- Symptoms may be nonspecific and indicative of other disorders.
Pulmonary Embolism - history
Ask about chest symptoms: The clinician must have a high index of suspicion and recognize risk factors to establish the correct diagnosis.
Pulmonary Embolism - physical exam
- Findings on physical examination are nonspecific.
- General:
- Fever
- Diaphoresis
- Nervousness or apprehension (altered mental status is uncommon)
- Cardiovascular:
- Increased intensity of the pulmonic component of S2
- Tachycardia
- Gallop rhythm
- New murmur
- Pulmonary:
- Tachypnea
- Rales
- Cyanosis (present with 65% obstruction of the pulmonary artery)
- Pleuritic chest pain
- Dyspnea
- Cough
- Hemoptysis
- Wheezing (uncommon)
- Extremities:
- Deep venous thrombosis is frequently found in the adult population.
- Phlebitis
- Edema
Pulmonary Embolism - tests
Pulmonary Embolism - lab
- In general, blood tests are nonspecific and of no significant value in making the diagnosis of a pulmonary embolus.
- Arterial blood gases:
- Decreased PaOIncreased alveolar-arterial (A-a) gradient
Pulmonary Embolism - imaging
- EKG:
- Useful in ruling out other conditions
- May show sinus tachycardia or nonspecific ST-T wave changes
- Echocardiogram:
- Useful for identifying:
- Abnormalities of cardiac anatomy
- Thrombi on catheter tips
- If emboli are seen on echocardiogram, mortality rate is 40–50%. Additionally, if signs of right ventricular dysfunction are noted (e.g., right ventricular dilatation, abnormal right ventricular wall motion, or increased tricuspid regurgitation jet velocity), risk of poor outcome is greater.
- Spiral CT:
- New diagnostic modality
- Greater sensitivity than ventilation/perfusion scan in the diagnosis of pulmonary embolism, due to the ability to image abnormal pulmonary pathology.
- Chest x-ray:
- May be abnormal in 70% of patients with pulmonary embolus
- Most frequent findings:
- Parenchymal infiltrates
- Atelectasis
- Pleural effusions: Seen in 33% of cases, mostly unilateral
- Hampton hump (pyramidal shape pointing toward the hilum)
- Ventilation/Perfusion scan
- Results of a ventilation/perfusion scan performed to rule out a pulmonary embolus are reported in 1 of 5 categories, ranging from high probability to normal.
- An abnormal ventilation/perfusion scan with normal ventilation and decreased perfusion in the appropriate clinical setting is 90% specific for a pulmonary embolus.
- A normal result on ventilation/perfusion scan does not completely rule out pulmonary embolus, although if the patient is at low risk, a pulmonary embolus is highly unlikely.
- Pulmonary angiography:
- Most sensitive and specific test
- Not done as frequently in children as in adults because of complications of the procedure
- With the introduction of newer, improved catheters and safer contrast solutions, this test can now safely be performed in the pediatric population.
- Indicated for cases:
- Intermediate-probability ventilation/perfusion scans
- High-probability scans in patients who are: Poor candidates for anticoagulation, hemodynamically unstable, or require an embolectomy
Pulmonary Embolism - diag proced-surgery
- Pulmonary function testing:
- Evaluation of the lower extremities:
- Diagnosing deep vein thrombosis via:
- Impedance plethysmography
- Doppler technology
- Venography
Pulmonary Embolism - differencial diagnosis
- Cardiac:
- Cardiac tamponade
- Constrictive pericarditis
- Restrictive cardiomyopathy
- Pulmonary:
- Chronic cough
- Status asthmaticus
- Pneumonia with empyema
- Pneumothorax
Pulmonary Embolism - TREATMENT
Pulmonary Embolism - initial stabilization
- Stabilize patient before anticoagulation or thrombolytic therapy is begun:
- Improve oxygenation.
- Correct acidosis
- Stabilize BP
- Analgesia for severe pleuritic chest pain. Avoid prescribing opiates in cases of cardiovascular collapse.
- Goal of therapy is anticoagulation and/or thrombolysis.
- In patients with an intermediate or high suspicion, begin anticoagulation before investigations.
Pulmonary Embolism - medication
- Anticoagulation therapy to prevent further thrombus formation
- Heparin:
- Bolus dose: 100–200 U/kg
- Maintenance dose: 10–25 U/kg/hr
- Keep PTT at 55–60 seconds
- Should be given for 7–10 days
- Coumadin:
- Coumadin should be started 24–48 hours after heparin therapy is begun.
- Maintenance dose: 2.5–10 mg/d
- Keep PT twice normal and maintain the International Normalized Ratio between 2.0 and 3.0
- Should be continued for 36 months
- Thrombolytic therapy:
- Agents available:
- Streptokinase: No difference in outcome has been found using streptokinase over urokinase.
- Urokinase
- TPA (tissue plasminogen activator): Same efficacy as streptokinase and lower incidence of allergic reactions
- Indications:
- Hemodynamically unstable
- Large embolus
- Low-molecular-weight heparin has been used as prophylaxis or as treatment for preexisting conditions in both adults and children.
- A synthetic, nonthrombocytopenic heparin pentasaccharide with pure antifactor Xa activity is currently being tested.
- Ticlopidine and clopidogrel have been used successfully to prevent thrombotic strokes and arterial thrombotic syndromes.
- Contraindications to anticoagulation therapy:
- Active internal bleeding
- Recent cerebrovascular accident
- Major surgery
- Recent gastrointestinal bleed
Pulmonary Embolism - surgery
- Embolectomy:
- Indicated when hemodynamic instability persists; reserved for patients who have failed thrombolytic therapy or in whom medical treatment is contraindicated.
- Late results are excellent if the patient has not suffered from a perioperative cardiac arrest, which is associated with early mortality.
- Percutaneous caval filtration:
- Indicated if commencement or continuation of anticoagulation is strongly contraindicated, or if full anticoagulation has failed to prevent recurrent emboli.
- This should be considered in patients undergoing venous thrombolysis, because up to 20% may develop embolization during treatment.
Pulmonary Embolism - FOLLOW UP
Patients receiving Coumadin therapy should have the usual follow-up for those receiving an anticoagulant.
Pulmonary Embolism - prognosis
- If treated promptly, prognosis is good
- If treatment is delayed, especially if the patient is hemodynamically unstable, prognosis is poor.
Pulmonary Embolism - bibliography
- Arcasoy SM, Kreit JW. Thrombolytic therapy of pulmonary embolism: A comprehensive review of current evidence. Chest. 1999;115:1695–1707.
- Evans DA, Wilmott RW. Pulmonary embolism in children. Pediatr Clin North Am. 1994;41:569.
- Fedullo PF, Tapson VF. Clinical practice. The evaluation of suspected pulmonary embolism. N Engl J Med. 2003;349:1247–1256.
- Goldhaber SZ. Elliott CG. Acute pulmonary embolism: Part I: Epidemiology, pathophysiology, and diagnosis. Circulation. 2003;108:2726–2729.
- Kruip MJ, Leclercq MG, van der Heul C, et al. Diagnostic strategies for excluding pulmonary embolism in clinical outcome studies. A systematic review. Ann Intern Med. 2003;138:941–951.
- Velmahos GC, Vassiliu P, Wilcox A. Spiral computed tomography for the diagnosis of pulmonary embolism in critically ill surgical patients: A comparison with pulmonary angiography. Arch Surg. 2001;136:505–511.
- Zierler BK. Ultrasonography and diagnosis of venous thromboembolism. Circulation. 2004;109(suppl 1):I9–I14.
- Qaseem A. Current diagnosis of venous thrombo-embolism in primary care: A clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Fam Med. 2007;5:57–62
- Snow V. Management of venous thrombo-embolism in primary care: A clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Fam Med. 2007;5:74–80.
Pulmonary Embolism - CODES
Pulmonary Embolism - icd9
415.1 Pulmonary embolism
Pulmonary Embolism - FAQ
- Q: Is it safe for children on Coumadin to play contact sports?
- A: The general recommendation is that no contact sports should be allowed while children are on Coumadin therapy, because of the increased risk of bleeding.
Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
More About Pulmonary embolism
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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