| |||||||||||||||
|
Home
|
For other articles and previous issues click here. August 2, 2004 Evaluating
Pediatric Trauma — Imaging vs. Lab Tests Research addresses questions about the value of lab tests in diagnosing abdominal trauma injuries. CT is effective but raises the issue of radiation exposure in children. FAST ultrasound shows promise, too. And don’t discount traditional physical examination. A 10-year-old is brought into the emergency department complaining of sharp abdominal pain after falling off some playground equipment. What’s the best way to assess the extent of that child’s injury? That’s the type of clinical question behind studies looking at the role of lab tests, imaging, and physical examination in pediatric abdominal trauma. Two recent studies conducted independently of each other—one at the Children’s Hospital in Boston and the other at Women & Children’s Hospital of Buffalo, New York— were both based on suspicions that laboratory evaluation had no significant impact on pediatric trauma patient treatment and outcomes. Their subsequent results have called into question the efficacy of protocol-driven laboratory assessments in evaluating abdominal trauma in children. Researchers from both hospitals presented their results at the annual Pediatric Academic Societies’ meeting in May. The findings suggest that more effective screening alternatives should be utilized, with CT looking like the most apparent alternative. That, in turn, raises recent questions and concerns about radiation exposure and the appropriateness of CT scanning for children. That issue cascades into more questions. Are there alternatives to CT? Does there even have to be an alternative? Focused abdominal sonography for trauma (FAST), a limited but rapid version of ultrasound, may provide an answer to at least one of those questions. Laboratory Protocols Led by Capraro, of the hospital’s division of emergency medicine, the researchers aimed to assess the sensitivity, specificity, and positive predictive value of lab tests for evaluating abdominal pathology in pediatric trauma patients. In particular, the group wanted to determine whether or not these routine labs were effective in evaluating intra-abdominal trauma in children. Such trauma labs have been used before and since CT became available, but few studies had examined the usefulness of these labs compared with CT. “We decided to do a study to see whether these lab tests actually show anything, so we retrospectively looked at 382 patients that had been seen by our trauma service over three years, and we looked at all of the lab studies that were done,” says Capraro. “For some of those studies, we compared how they helped effect, if at all, treatment for abdominal trauma.” Capraro said several previous studies had looked at how lab results impacted patient outcomes but none yielded anything concrete. For this study, Capraro and colleagues reviewed the patients’ charts (average age of 10) who had been evaluated for pediatric intra-abdominal trauma and had undergone both trauma labs and abdominal CT imaging. They compared the lab results with the CT scans. At the time, routine trauma labs were the standard of care. Using Chi square analysis, they compared abdominal pathology found on CT scans with lab values for sodium, glucose, white blood cell count, hematocrit, platelets, prothrombin time, activated partial thromboplastin time, aspartate aminotranserase, alanine aminotransferase (ALT), amylase, lipase, and hemoglobin detected on urinalysis. The study deemed lab findings abnormal if they fell outside of the hospital’s respective normal range. “It wasn’t as though we took a look at varying levels of the test. We just labeled them as normal or abnormal,” explained Capraro. “For example, we looked at sodium levels because people were sending off electrolyte samples; then we looked at some of the events, and if it was out of the range of normal for our hospital, we labeled that as an abnormal finding on lab studies. If it was normal, we labeled it as ‘normal.’ We took that value and compared them to CT scans.” Boston Results The study conducted by researchers at The Women & Children’s Hospital of Buffalo was precipitated by similar suspicions and yielded similar results. Like their Boston counterparts, these researchers wanted to find out whether or not the routine laboratory panels for pediatric trauma had any significant predictive value or impact on treatment and outcomes. The team—which included pediatrician Scott M. Bouton, MD; Graidi Keleher, RN, BSN; Usha Sankrithi, MD; and Guy F. Brisseau, MD—also conducted a retrospective chart review. They looked at records of all pediatric trauma patients admitted to the hospital and evaluated by the pediatric trauma team for a 47-month period (February 1, 2000, through December 31, 2003). Researchers collected data on age, sex, mechanism of injury, injuries suffered, laboratory studies, x-ray and CT results, and discharge diagnosis for the 464 patients (average age of 10). Bouton and colleagues also reviewed follow-up visits to the surgery clinic for outcome and complications. The number of tests performed on these patients was high: 7,500 initial labs and an additional 7,100 tests ordered within the first 24 hours. Abnormal results were low (732, or less than 10%), and Bouton reported that any abnormal results didn’t match any real intra-abdominal injuries. The results bore out the team’s suspicions. They concluded that a large number of lab studies, driven by protocol, are conducted in this patient population and that these tests have limited value and little impact on treatment and outcome. Alternative Directions The team from Boston thinks physicians should set up tests only when they deem necessary following a complete physical exam and that the mechanism of injury and the physical exam should dictate who moves on to get imaging. “What this study shows, I think, is that not every pediatric trauma patient needs to get all of the tests,” says Capraro. “The tests should not be automatic for everyone. Most emergency medical physicians would still do a baseline blood count, but beyond that, the panel of tests would be pared down to what is felt to be necessary as opposed to automatic.” Even when pared down, Capraro thinks tests would not be as useful as CT. “Based on our findings, which show that none of these labs help predict CT findings, I think the CT scan is invaluable in the evaluation of pediatric trauma patients,” he says. “If no CT scan is available, then you would send off these lab tests as a kind of adjunctive care. But what should happen next, we feel, is that the patient gets stabilized and then immediately sent to a trauma center where they can get a more appropriate evaluation.” CT Scanning Risks However, CT imaging for pediatric patients adds the risk of radiation exposure. Younger children have an increased radiosensitivity of certain structures and tissues, including the thyroid gland, breast tissue, and gonads. Also, because of their age, children have more time to develop radiation-induced cancer. In recent years, mainstream press coverage generated fear among some parents and healthcare professionals that clinicians were routinely prescribing CT scans for children heedless or unaware of radiation risk. Certainly, the degree of that risk is debated. A positive factor is the emergence of new CT technology, such as helical CT and multidetector scanners, which decrease scan time and thus reduce radiation exposure. Many believe the risks of CT are far outweighed by the life-or-death urgency inherent in pediatric abdominal trauma situations. Capraro firmly believes the benefits of an accurate diagnosis are far more important. “…We certainly have to explain to [patients and their parents] what is going on,” he concedes. “Recent studies have definitely raised a concern about ionized radiation, and I think it’s a valid concern. But if we are talking about something significant going on with the patient, then that could literally mean life or death. I think people feel that what is best for the patient right now is a CT scan, so that we can get a better understanding of the pathology rather than being concerned about what might happen 10 or 20 years from now.” Ultrasound Alternative If the physician detects injuries to organs like the liver and spleen, or finds signs of intra-abdominal bleeding, Capraro notes that information can help determine whether the patient needs to be sent to the operating room or on for more imaging. “The modality hasn’t moved from the adult ER into the pediatric ER yet, but it is going to be an exciting topic,” he comments. “You’re going to be hearing about it more, and I think it’s going to moving into the pediatric ER in the near future.” FAST is noninvasive and accurate, and it provides some important advantages over CT, especially in the context of life-and-death trauma situations. The exam is quicker to perform (it can be accomplished in as little as three minutes) and easier to interpret, there’s no radiation exposure, the equipment is portable, and the exam is less expensive. But it has its limitations. The technique has a significant false-negative rate. Also, CT has better specificity and is more effective in localizing an injury. “I don’t think it will completely replace CT,” says Capraro, “but I wouldn’t be surprised to see it being used more in emergency pediatric departments and to see more studies being done.” The studies conducted at Children’s Hospital and The Women & Children’s Hospital of Buffalo have provided evidence that the standard lab tests used to evaluate pediatric patients are of little predictive value. CT is an effective alternative, but the radiation risk—and communicating that risk to parents—needs to be truly included in decision making. Other alternatives, including ultrasound and physical examination, merit further investigation and comparative study. — Dan Harvey is a freelance writer and frequent contributor to Radiology Today. |
 |
|
3801 Schuylkill Rd • Spring City, PA 19475 Publishers of Radiology Today All rights reserved. |