Davenport assessing an image with another health care professional. Credit: Michigan Medicine
July 5, 2022 — In April 2022, a shutdown of Shanghai due to China’s “zero COVID” policy caused a global shortage of iodinatedcontrast mediaproduced by GE Healthcare. Many health systems, roughly half the market share in the United States, useGE Healthcare作为他们首选的造影剂供应商，通用电气医疗集团的造影剂制造业务主要集中在上海。
造影剂被用来改善诊断性成像，造影剂的短缺影响了数以百万计的检查。More than 50 milliondiagnostic imaging examinationsusing contrast media are conducted annually, including nearly allangiographyand approximately half of allCTscans. Contrast media is necessary for some types of exams, such as evaluation of the heart arteries and CT for acute bleeding, and improves diagnostic accuracy for others, like CT for cancer or infection.
GE Healthcare has been increasing production at its Shanghai facility, has increased production at its facility in Ireland and has been airlifting contrast media to the United States. It’s estimated that production should be normalized by the end of June 2022. However, China is still pursuing a zero-COVID policy, so the future remains unpredictable, saysMatthew Davenport, M.D., a radiologist atUniversity of Michigan Healthand vice chair of the commission on quality and safety for theAmerican College of Radiology.
“During this acute shortage, health systems have been forced to compare their stock-on-hand with the anticipated return-to-normal date to determine how aggressively to conserve contrast material,” Davenport said. “The goal has been to avoid running out, which would prevent imaging of patients for whom contrast media was necessary, and to conserve contrast media in a way that is safest for patients.”
In a recent letter published inJAMA, Davenport and a team of researchers modeled several ways to conserve contrast media. They found that a combination of methods couldreduce contrast media use for CT scans by approximately 80% if a moderate reduction in diagnostic accuracy could be tolerated:
Weight-based dosing and changing CT settings
In the analysis, researchers examined what would happen if a system switched from fixed doses of contrast media to selecting the dose of contrast media based on the weight of each individual patient.
The team found that for a model of 1 million CT scans, moving to weight-based dosing could reduce contrast media use by 12%.
The second method they examined was changing the settings on the CT scanner, allowing the machine to better detect smaller amounts of contrast media. This adjustment, Davenport notes, works best for smaller patients.
他说:“由于图像噪声增加，这种策略不适用于较大的患者。”“但是对于体重在80公斤以下的小个子病人，造影剂的剂量可以减少40%。”
Unenhanced CT: CT without contrast material
If you are performing a coronary angiogram to examine the arteries of the heart, or a CT scan to look for a possibly fatalaortic dissection, contrast media is required. Imaging of the blood vessels with CT scan or fluoroscopy tends to necessitate use of contrast media. Davenport likens this to using a flashlight in a dark room. Without the flashlight, nothing can be seen.
Some imaging can be done with “unenhanced CT,” without using contrast media. However, in many cases, this results in a loss of diagnostic accuracy. A correct diagnosis can often be made, but in some patients, it may be wrong or incomplete. Davenport compares this to the lights on an ambulance.
“You can probably still see the ambulance without the lights but having the lights on the ambulance makes it much more likely you will see it,” he said. “The lights and sirens on an ambulance make it easier to perceive. It’s similar with contrast media.”
Eliminating contrast media by using unenhanced CT conserves far and away the most contrast media (78%), but only if a moderate reduction in diagnostic accuracy can be tolerated.
Systemic changes needed
Most hospitals affected by the contrast media shortage have already made local decisions about how to preserve contrast media and reduce use. However, Davenport says, the shortage raises serious questions about supply chain risk. It will be important to minimize the chance of this happening in the future, Davenport says.
大多数医疗系统通过单一供应商购买大部分造影剂，比如通用电气医疗，通过优先供应商合同节省资金。尽管通用电气加大了造影剂生产，但中国的新冠肺炎疫情可能会再次阻碍供应链。
达文波特说:“无论是源自中国的造影剂，还是源自美国的婴儿配方奶粉，供应链冗余都是我们用艰难的方式重新吸取的重要教训。”“当卫生系统做出购买决定时，他们应该将供应链的稳健性作为一个潜在风险。造影剂和婴儿配方奶粉对健康很重要，每天都要使用。我们需要将失去关键产品的风险降到最低。我们不能把太多的鸡蛋放在太少的篮子里。”
Despite the challenges, Davenport says he respects the professionalism of the many health care providers managing the contrast media shortage.
“Nobody wants to be in this situation, but I have been continually impressed by the level of diligence and responsibility that has gone into troubleshooting this issue,” he said.
Additional authors include: Philip Chu, M.S.,Rebecca Smith-Bindman, M.D., both of the Department of Epidemiology and Biostatistics,University of California, San Francisco,Timothy P. Szczykutowicz, Ph.D., Department of Radiology,University of Wisconsin, Madison.
Paper cited: “Comparison of Strategies to Conserve Iodinated Intravascular Contrast Media for Computed Tomography During a Shortage,” JAMA.DOI: 10.1001/jama.2022.987
For more information:https://med.umich.edu/
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August 10, 2022
