Pan-Scans Generate Conclusive Diagnoses of Severe Trauma

James Brice

March 07, 2012

March 7, 2012 — An evaluation of nearly 1000 trauma cases at a designated hospital for injury treatment in Berlin, Germany, has added some scientific certainty to the long-held brief that whole-body computed tomography (CT) quickly and accurately diagnoses trauma for severely injured patients.

So-called pan-scans have been employed in emergency departments for trauma since the advent of ultrafast, multidetector computed tomography in the late 1990s. They have been praised for eliminating the need for many diagnostic steps between clinical suspicion and definitive proof of injuries requiring immediate therapeutic attention.

But the controversial imaging procedures have also been questioned for exposing patients to extremely high levels of ionizing radiation. A typical 20-mSv dose is double the amount of ionizing radiation the National Academy of Science's Seventh Assembly of the Committee on Biologic Effects of Ionizing Radiation says will give a 40-year-old adult a 1-in-1000 chance of future cancer.

The actual risks of pan-scans are subject to debate, but their benefits may now be more certain, thanks to an analysis by Dirk Stengel, MD, PhD, from the Centre for Clinical Research, Unfall Krankenhaus Berlin, and the Department of Trauma and Reconstructive Surgery, Ernst Moritz Arndt University Medical Center, Greifswald, Germany, and colleagues.

The study was published online March 5 in the Canadian Medical Association Journal.

The authors determined that only 7.8% of the pan-scans performed on 982 patients from 2006 to 2008 were deemed clinically unnecessary. Forty of these 77 patients had minor injuries.

A case-by-case analysis established consistently high specificity (97.5% - 99.8%) for injuries localizing to 5 body regions from the pelvis to head and neck. In contrast, the sensitivity was variable, ranging from 79.6% and 86.7% for detecting injuries in defined regions of interest. A higher range of sensitivities (from 85.3% to 92.1%) was calculated for patients with multiple trauma, again depending on the region of interest. Imaging was performed on a 64-slice CT scanner.

Optimal accuracy was achieved when the whole-body CT scan was performed from 24 to 34 minutes after admission, the authors note. The sensitivities and specificities during this time were 83.8% to 88.3% and 98.3% to 100%, respectively, depending on the anatomic region of interest.

The authors attribute the test's peak accuracy during the specified time to the better visibility of lesions possible after blood circulation and tissue perfusion are restored. Allowing a short delay before scanning was also associated with less time pressure on the radiologist when reviewing the CT images, they write.

"Screening tests in trauma are intended to immediately detect life-threatening injuries," the authors write. "Given this premise, high specificity makes pan-scanning a valuable tool for priority-oriented treatment planning."

The findings were drawn from Pan-Scan for Trauma Resuscitation (PATRES), a program for assessing the accuracy of pan-scans developed by Dr. Stengel and colleagues. All in-hospital and outpatient clinical, radiologic, and interventional data pertaining to a patient's progress and outcome were considered when assessing a pan-scan's appropriateness and accuracy for this study.

Study limitations, according to the authors, included its single-center design, a trauma algorithm that did not allow comparisons between pan-scans and conventional diagnostic workups, and an imperfect reference standard that may have introduced partial verification bias. Other factors may have led to the underestimation of pan-scan sensitivity. The clinical implications of incidental findings in one third of the whole-body CT studies were not addressed.

Stefan Huber-Wagner, MD, from the Trauma Surgery Department at Munich University Hospital, found that the integration of pan-scans into early trauma care significantly increased the probability of survival for 1494 patients with polytrauma, who underwent the procedures as part of a retrospective, multicenter study (Lancet. 2009;373:1455-1461).

Anesthesiologist Thomas Erick Wurmb, MD, from University Hospital of Wuerzburg, Germany, found from a retrospective comparison of pan-scans and a conventional diagnostic workup for multiple trauma that the whole-body CT approach shortened the time from emergency department admission and the start of surgery. Mortality did not significantly differ between the 2 groups (Emerg Med J. 2011;28:300-304).

In the United States, Carlo L. Rosen, MD, vice-chair for emergency medicine education at Beth Israel Deaconess Medical Center, Boston, Massachusetts, did not review the latest study specifically, but in an interview with Medscape Medical News he described clinical situations in which pan-scans have shown the most value in his emergency department. They include patients whose clinical assessments are difficult to perform because of intubation, unconsciousness, or altered mental states. Pan-scans are ordered for patients who have normal vital signs in the emergency department but a history of hypotension in the field suggesting significant injuries requiring surgery. Elderly patients with a mechanism of injury are also candidates because their injuries are generally hard to evaluate, he said.

The authors recommended a multicenter trial to confirm their findings and new international criteria for appropriate applications of whole-body CT for trauma in the ED.

Dr. Stengel is a board member of and a consultant for the German Trauma Association; is a consultant, has provided expert testimony for, and received payment for lectures for German Federal Statutory Accident Insurance, Biomet, DePuy, Stryker, and the AO Foundation; and holds grants from these agencies, as well as from the Federal Ministry of Education and Research and the European Commission. One coauthor is a board member and has received payment for providing lectures from the German Advanced Trauma Life Support and has received compensation for travel expenses from the North American Treaty Organization for providing a lecture on trauma management. Another coauthor is a consultant for Pfizer, Stryker, and Novo Nordisk; has provided expert testimony for DePuy, Rehavital, and Medkon; and has received payment for lectures from Johnson & Johnson Medical, Depuy, Medkon, and Rehavital. The other authors have disclosed no relevant financial relationships.

CMAJ. Published online March 5, 2012. Abstract

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