What Are Pulmonary Embolism Risk Factors?

Patient Presentation
A 17-year-old female came to clinic for followup of pneumonia that had been diagnosed when she was on vacation 1 week previously. She had been coughing for a couple of days, and the cough was worsening. She developed some shortness of breath and right-sided chest pain, so her parents took her to the local emergency room. “In the emergency room, they thought I might have a blood clot, so I had to have a CAT scan that they said was normal. They gave me medicine in my arm which helped with the chest pain and then gave me some pills for the pain. I took them for a couple of nights to sleep but stopped after that. I’m also almost done with the antibiotic they gave me,” she explained. Her mother said that the doctors were worried about the blood clot because the patient was using birth control pills for dysmenorrhea and the patient’s maternal aunt had had a blood clot that went to her lung. “She found out a few months ago that its a blood problem. I don’t know exactly what it is but my sister is supposed to let me know. I guess we haven’t told you that yet so you don’t know. It’s new in our family,” described the mother. The teenager said, “I’m doing a lot better now with a lot less coughing but some is still there. The pain has gone away.”

The pertinent physical exam showed normal growth parameters and vital signs with a respiratory rate of 18 per minute and an oxygen saturation of 99%. HEENT revealed some minor rhinorrhea with a small amount of serous fluid in her ears bilaterally. Her lung examination still had slightly decreased breath sounds on the right but no obvious crackles. Chest pain could not be provoked.

The diagnosis of right lower lobe pneumonia that was resolving was made. The physician recommended that the mother find out what the cause of the aunt’s blood clot was so that the family members could be evaluated if necessary. He also noted the information in the medical record.

Discussion
Pulmonary embolism (PE) is potentially life-threatening but fortunately rare event especially in the pediatric population. It was first described in children in 1861. PE is likely underreported because of minimal or non-specific clinical symptoms. The incidence is estimated at 0.05-4.2% with the 4.2% based on autopsy reports. It is probably also increasing as more central venous catheters (CVC) are used, and more children are surviving previously poor prognostic diseases. There is a bimodal distribution with cases < 1 year (especially neonates which account for ~50% of this group) and in teenagers. Neonates appear to have a high rate because of increases in CVC use and teenagers risks are felt to be increased with oral contraceptive use. Oral contraceptives alone are rarely felt to be solely responsible for PE though. Recurrence rate is 7-18% and death with PE is ~10% with the main cause being the patient's underlying medical condition.

Venous thrombosis can occur when there is injury to a vessel wall, venous stasis and hypercoagubility. Pulmonary embolism occurs when the thrombus is dislodged, moving through the blood vessels, through the right side of the heart and lodges in the pulmonary arterial system. Patients may have no symptoms if the thrombus involves less than 40-50% of the pulmonary circulation. Through various mechanisms, PE can cause hypoxia, hemodynamic instability and cardiopulmonary collapse. Massive PE where the pulmonary blood flow is occluded to the point of hemodynamic instability is rare in children. Massive PE can present with dyspnea, hypoxemia, hypotension, syncope, right-sided heart failure and sudden death.

Classically, PE presents with shortness of breath, chest pain and hemoptysis. These symptoms only occur in some patients. Deep venous thrombosis (DVT) symptoms of a painful extremity can also occur. In children, upper extremity DVTs are more common than in adults as more upper extremity CVCs are used in children. Unexplained tachypnea may be another non-specific finding that points towards PE. Pleuritic chest pain, shortness of breath and cough were more likely to be found in children evaluated for PE.

PE is rare so the differential diagnosis includes more common disease processes such as pneumonia, atelectasis, pneumothorax, and empyema. Congenital abnormalities and malignancies also need to be considered in the proper circumstances.

The diagnosis of PE can be difficult as noted. D-dimer testing is a sensitive screening test for adults, but can be normal in many children (15-40%) with known PE. Electrocardiogram with right-sided cardiac changes may be seen but again are less common in children. Arterial blood gas can show hypoxemia, hypercapnea and respiratory alkalosis. Echocardiogram can be helpful in some children particularly those with known congenital heart disease. Chest radiographs are frequently normal but can show hypovascularity in affected areas, wedge-shaped densities or a prominent central pulmonary artery. Computer tomography-pulmonary angiography is the primary imaging modality for PE diagnosis but other types of imaging may be used such as magnetic resonance imaging.

Treatment is usually with anticoagulants, potential thrombectomy or thrombolysis, and treatment of any underlying cause identified. Prevention includes ambulation and movement, adequate hydration, anticoagulants (usually for a period of time only), and inferior vena cava filters.

Learning Point
PE usually occurs in children with known risk factors with up to 80-96% having an identifiable problem, whereas in adults up to 30% are idiopathic.

Risk factors for PE in children include:

  • Congenital heart disease
  • Central venous catheters
  • Deep venous thrombosis – current or previous
  • Hypercoagulable states including malignancies, nephrotic syndrome and sickle cell disease
  • Immobilization
  • Obesity
  • Medications including oral contraceptives or other estrogen use
  • Prothrombic states including anti-phospholipid antibodies, Factor V Leiden, Protein C, and Protein S
  • Pulmonary embolism – previous
  • Recent surgeries
  • Trauma

Questions for Further Discussion
1. What are causes of sudden death in children? A review can be found here
2. What are causes of wheezing? A review can be found here
3. What are causes of chest pain? A review can be found here

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Pulmonary Embolism

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Navanandan N, Stein J, Mistry RD. Pulmonary Embolism in Children. Pediatr Emerg Care. 2019;35(2):143-151. doi:10.1097/PEC.0000000000001730

Ramiz S, Rajpurkar M. Pulmonary Embolism in Children. Pediatr Clin North Am. 2018;65(3):495-507. doi:10.1016/j.pcl.2018.02.002

Ignjatovic V. Paediatric pulmonary embolism: a pathway to improved outcomes. Lancet Haematol. 2019;6(3):e115-e116. doi:10.1016/S2352-3026(19)30012-2

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa