Moving some critical care patients from the intensive care unit to the imaging suite is simply not an option. So radiologists from the Virchow Klinikum, Charité Hospital in Berlin investigated the feasibility of using a portable chest CT scanner for high-risk ICU patients. They presented their results at the 2001 RSNA meeting in Chicago last week.
"These are patients who have no access to the radiology department," explained Dr. Ulf Teichgraeber. "Performing chest exams on nontransferable patients can have a direct effect on their treatment and the therapeutic consequences."
For the study, 93 portable CT scans were done in a special interventional suite in the ICU unit, or were conducted as a bedside procedure. The bedside option has a drawback, however. If there is another patient in the room, he or she will have to be relocated to accommodate the scanner, Teichgraeber said. The Tomoscan M entry-level mobile scanner was used (Philips Medical Systems, Bothell, WA). The gantry table, tube, and workstation are all battery-operated, he said.
The assessment of the patient’s risk factors for transportation were determined by two ICU scoring systems -- the multiple organ dysfunction score (MODS) and the therapeutic intervention scoring system (TISS-28) -- as well as independent review by an ICU physician.
Finally, the group evaluated the additional diagnostic gain and therapeutic consequences of transporting the patient.
"TISS-28 is an assessment of patient care. This is an indirect evaluation of the patient’s health status," Teichgraeber said. "[MODS] is for the assessment of the patient’s physiological state, and this is used for direct evaluation of health status. MODS tells us the mortality probability of the patient."
A total of 24 patients underwent 37 chest examinations with the portable CT. On the day of the CT exam, 77% of the patients needed maximum intensive care according to TISS-28 (>40), and 53% were at risk for mortality of higher than 25% on MODS. However, most of these patients could be moved into the interventional suite on the ICU unit. In two cases, ICU doctors determined that these patients could not be transported. These procedures were done at bedside.
According to the results, the portable CT scans done in the ICU were sufficient to establish diagnosis in 80% of the cases; in 20%, the CT exam offered additional diagnostic information along with chest x-ray. In all, 30% of the portable CT exams led to direct therapeutic consequences.
Besides the inconvenience of having to remove other patients, portable CT done at bedside does have other flaws. First, the image quality of hospital-room scans is adequate, but scans done in the ICU interventional suite are better. More significantly, portable CT is a labor-intensive and time-consuming process: One bedside chest CT exam can take anywhere from 2.5 to 4.5 hours, including the time required to move equipment and post-processing.
"You might say that this is totally crazy. But you have to consider that these patients you’ll never, ever see in the radiology department. These are patients who are just not transferable for CT scans," Teichgraeber said. In most cases, the ICU doctors deemed the CT scan necessary for the treatment protocol, he added.
By Shalmali PalAuntMinnie.com staff writer
December 5, 2001
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Three-year study finds portable abdominal CT useful, November 27, 2001
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