CHICAGO – When a trio of radiologic technologists left his Philadelphia hospital due in part to the ballooning number of off-hour requests for V/Q exams, Dr. Charles Intenzo decided to find out why the ER was so partial to lung scintigraphy. Intenzo and his co-authors at Thomas Jefferson University measured the frequency with which ER doctors ordered ventilation/perfusion scans for suspected pulmonary embolism (PE) over a five-year period.
“Why even complain about this?” Intenzo asked during a presentation at the RSNA conference on Monday. “It’s business [for the nuclear medicine department]. The problem is that a lot of those requests come at off-hours. More over, our RTs began to complain about the number of scans they were doing at night that [had normal results]. We lost three RTs this year because of the growing number of night calls.”
Using a list of patients referred from the ER for V/Q scans between 1995 and 1999, the group found their numbers increased each year. In 1995 lung scintigraphy was performed on 152 patients, compared to 177 in 1996, 179 in 1997, 274 in 1998, and 292 in 1999.
In 1995, 33.14% of the scans had normal results. A year later, that percentage climbed to a little over 50%. In the next three years, the number of normal scans rose from 64% in 1997 to 72% in 1999.
Intenzo suggested three trends that he and his colleagues had spotted in this growth rate. First, over the five-year period, more scans were requested by junior attending staff than senior staff. Second, the ER requests for V/Q scans were seasonal, with significant jumps noted in the early summer, when new staff came on board, and in mid-winter when pneumonia and chronic obstructive pulmonary disease (COPD) cases increased.
Finally, on the rare occasions that a V/Q scan reported a high probability of pulmonary embolism, it seemed to trigger more orders for lung scintigraphy.
“A high probability scan is the kiss of death,” Intenzo said. “That indicates that the ER threshold for PE is so low, they feel the need to order nothing but lung scans.”
When Intenzo asked the ER physicians why they ordered V/Q scans, they offered several reasons, some of which Intenzo deemed acceptable, including dysapnea, tachycardia, or a report from a radiologist stating that an x-ray could not rule out PE.
However, reasons that Intenzo said were not valid included EKG changeability, a prolonged airline flight that may have caused deep vein thrombosis, or an episode of PE that took place more than 30 years ago. Another dubious excuse for scintigraphy: “The patient’s husband is the chairman the urology. In this case, the chairman’s wife did not have PE but pneumonia.”
When ordering these scans, ER physicians also tend to omit important patient history, such as a history of COPD or the inhalation of recreational drugs. ER doctors also want V/Q scans for patients who have shortness of breath because of chest trauma, such as people who had been in car accidents, he said.
“ER doctors definitely abuse lung scintigraphy. The word [abuse] is justifiable if not lenient,” he concluded.
When an audience member asked if the advent of spiral CT had done anything to lessen the nuclear medicine’s load, Intenzo said he was wary of referring patients to other departments.
“I didn’t want to lose lung scan business during regular hours by refusing to do off-hour scans,” he explained “As it is, our CT people get abused regularly for abdominal scans so I wanted to ease their burden.”
Another session attendee suggested the ER department look into plasma D-dimer measurements, a noninvasive diagnostic test for PE. In a separate RSNA conference presentation, investigators from Grenoble, France used plasma D-dimer on 688 patients and found that it successfully ruled out PE in 46% of these cases, where the results were confirmed with Doppler ultrasound.
A third audience member cautioned against discouraging ER doctors from requesting V/Q scans because “PE is a devastating disease. I’m not sure what the right percentage of normal scans is but I would hesitate to come down too hard on these clinicians when they have a reasonable suspicion,” she said.
Intenzo agreed with another attendee that the best way to cut down on the number of lung scintigraphy exams ordered by the ER is to educate those clinicians on the benefits and pitfalls of the modality.
By Shalmali PalAuntMinnie.com staff writer
November 28, 2000
Copyright © 2000 AuntMinnie.com
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