LAKE BUENA VISTA, FLA. -- Venous thromboembolism is "not that uncommon in children" and seems to be on the rise, Dr. James Callahan said at the Advanced Pediatric Emergency Medicine Assembly.
In the general pediatric population, annual incidence is around 1 per 100,000. In hospitalized children, the number is much higher -- up to 57 per 100,000. Rates of pulmonary embolism and deep vein thrombosis have increased markedly over the past decade, said Dr. Callahan of the Children's Hospital of Philadelphia.
Michele G. Sullivan/IMNG Medical Media
Dr. James Calahan
"National hospital discharge data show that the disorders increased by about 70% from 2001 to 2007, and other studies show similar increases in other countries," he noted.
Although no one really knows the reason behind this increase, it's probably linked to better medical care for children with chronic illness. "As we keep children with more and more complex diseases alive longer and longer, we're going to keep seeing this trend," he said at the meeting, which was sponsored by the American College of Emergency Physicians and the American Academy of Pediatrics.
VTEs can be harder to recognize in children than in adults. The symptoms can be subtle and nonspecific. When signs and symptoms do occur, Dr. Callahan said, "we may not have PEs and DVTs high on the list of possibilities for children, so we can miss them. Sometimes it takes a while to figure it out. In autopsy studies, up to 4% of children showed signs of a pulmonary embolism or DVT. Only half of them had any symptoms at all, and a DVT was suspected in only about 15%."
Risk peaks at two times during a child?s life: in babies younger than 1 year and in older teens. In infants, the incidence is often linked to prematurity and the need for an indwelling catheter. The second peak is in teens around 15-18 years old who don't have any underlying illness. These cases account for about 50% of childhood DVTs. In older children, the pathophysiology is similar to what's seen in adults -- they have some circulatory stasis, get a clot, and it breaks off.
A minority of children who develop a DVT or PE have some chronic predisposing illness -- often a thrombophilia, but renal disease, systemic lupus erythematosus, and even some medications also can be underlying culprits. The indwelling line remains the single biggest risk factor for children of all ages.
Pleuritic chest pain, the most common symptom, is present in up to 84% of cases. The incidence of dyspnea, at 58%, is much lower than in adult patients. About half of children with a VTE will cough, and about a third show hemoptysis. Children are likely to be hypoxemic and tachypneic, run a fever, and have abnormal breath sounds and increased second heart sound.
Hypoxemia can be a very telltale sign. "If I see that in a child in the absence of pneumonia, I start to get worried. If I see an adolescent who presents with unexplained pleuritic chest pain, dyspnea, hypoxemia, and one risk or more of the risk factors, I go looking for it," Dr. Callahan said.
The Wells criteria -- a classic risk stratification system for adults -- just doesn't work in children. "Even if you change the numbers to make it age specific, it's not really helpful," he said.
Sinus tachycardia is the most reliable cardiac sign for pulmonary embolism in a child, but the ECG is completely normal in up to 25%. D-dimer levels are helpful in adults but have never been validated in children. A ventilation/perfusion scan is useful in otherwise healthy children, but "many of these kids have underlying disease, and that can make it inaccurate," he pointed out.
CT angiography is probably the most reliable diagnostic tool. "The scan is quick, which is good, but the child has to be immobilized and you need at least a 22-G intravenous cannula and may need a 20-G," Dr. Callahan said.
The treatment approach for children is also different than it is for adults, Dr. Callahan said. "There are no good studies on thrombolysis for children, but in certain cases -- such as a massive PE with hemodynamic instability -- it can be considered."
There are strict contraindications, however, including major surgery needed within 7-10 days; active bleeding; surgery on the central nervous system; ischemia, trauma, or hemorrhage within the past 30 days; recent seizures; a low platelet count and fibrinogen level; and uncontrolled hypertension.
Tissue plasminogen activator has not been well studied in pediatric populations and isn't indicated for use in children, but it is often used off label. Low-molecular-weight heparin has become the treatment of choice for most. Its longer half-life and more predictable response make it a good choice for children, who will also need less frequent monitoring.