For assessing severe trauma, whole-body CT can prove, but not definitively exclude, the presence of injuries and should be performed later than 30 minutes after admission to an emergency department for optimal results, according to a study published in the March issue of Canadian Medical Association Journal.
In recent years, whole-body CT, or pan-scanning, has been proposed as an alternate to the traditional staged diagnostic approach to severe trauma assessment, which is comprised of a physical exam followed by ultrasound, x-ray and CT.
“Pan-scan algorithms have been shown to accelerate diagnostic work-up, but their effect on survival is controversial,” wrote Dirk Stengel, MD, PhD, of the Center for Clinical Research, Unfallkrankenhaus Berlin and Ernst Moritz Arndt University Medical Center, in Berlin and colleagues. Other concerns include radiation exposure and “often uncritical use of CT scanning.” Moreover, the reliability of positive and negative findings whole-body CT has not been determined to date.
Stengel and colleagues sought to determine the accuracy of whole-body CT in identifying head and neck, facial, thoracic, abdominal and pelvic ring injuries in trauma patients.
The researchers examined data from 982 trauma patients who had been immediately transferred to the emergency department at Unfallkrankenhaus Berlin after injury between July 2006 and November 2008. The metropolitan trauma center followed the German Trauma Association pan-scan algorithm and ordered a whole-body trauma CT in the following situations:
- If there was an injury mechanism that exposed the patient to a high risk of multiple trauma;
- If a technical rescue was required;
- If the patient had impaired physical or physiologic status; or
- If the suspicion of severe trauma was confirmed by paramedics or emergency physicians on the scene.
Two reviewers analyzed the records of the trauma patients and used all collected data pertaining to patient progress and outcome as the diagnostic reference standard to validate the accuracy of CT.
Stengel et al found that 36.7 percent of patients were diagnosed with multiple traumas. They determined that 7.8 percent of pan-scans were unnecessary, and selective scanning would have been sufficient in these cases. Furthermore, in 6.3 percent of patients, the CT exam missed injuries that required monitoring in the intensive care unit or surgical treatment. The primary diagnostic gaps related to injuries that demarcate after fluid resuscitation.
“The pan-scan protocol was consistently specific (97.5-99.8 percent) but sensitivity was variable (79.6-86.7 percent) for detecting injuries in the body regions of interest,” wrote Stengel. The researchers observed the optimal accuracy of the pan-scan was between 24 and 34 minutes after admission, with scans performed about 30 minutes after admission achieving the best balance between sensitivity and specificity.
"The pan-scan performs best 30 minutes after admission, because the sensitivity of the scan increases after this interval," Stengel said in a statement. "The transfusion of fluids, blood, plasma and emergency interventions to stabilize circulation will restore organ perfusion, and make bleedings and hematomas visible on CT scans." Healthcare teams should verify negative results to rule out false-negative results with additional clinical observation, follow-up examination or further imaging.
The researchers noted that injuries visualized only via whole-body CT may be overemphasized. “However, our data give support to the alternative theory that a primary pan-scan effectively omits many diagnostic steps between clinical suspicion and definitive proof of injuries that require immediate therapeutic attention,” the authors wrote.
"Pan-scan algorithms reduce, but do not eliminate, the risk of missed injuries, and should not replace close monitoring and clinical follow-up of patients with major trauma," Stengel et al concluded.
For additional reading, a recent study published in Emergency Medicine Australasia linked the pan-scan trauma protocol with an increase in the proportion of patients exposed to more than 20 mSv of radiation.