NEW ORLEANS — A week in the intensive care unit (ICU) can expose critically ill patients to radiation levels that exceed yearly or even 5-year cumulative limits set by federal officials for occupational exposure, a researcher reported here.
In a retrospective observational review of data on 21,108 patients treated at an academic medical center ICU over a 5-year period, 4% of patients received cumulative effective doses (CED) of radiation ≥50 mSv, which is the yearly limit set by the Occupational Safety and Health Administration (OSHA), according to Sudhir Krishnan, MD, of the Cleveland Clinic in Ohio.
The 5-year cumulative limit of 100 mSv was met or exceeded by 1% of patients, even though the average length of stay in the ICU was around 5 days, he reported at CHEST 2019, the annual meeting of the American College of Chest Physicians.
Krishnan told MedPage Today that while the percentage of patients receiving very high doses of radiation was small, the analysis of ICU exposures probably underestimated total exposures received by critically ill patients.
“I believe my numbers greatly underreport exposures, and no national, regional, or local body is currently following these patients to see if this is an issue,” he said. “One could argue that the benefits of all this imaging far outweigh the risks in this patient population, but no one is really looking at this, so we don’t know.”
He said much of the radiation exposure among patients in ICUs comes from CT scans.
“We are trigger happy when it comes to performing CT scans in the ICU,” Krishnan stated. “It’s easy to get one, and the vast majority of them are negative. It may be reassuring to a physician to do a CT scan and find nothing, but is it the right thing to do?”
Clinical and radiological data were derived from electronic health records and other sources, and radiation doses from ionizing radiological studies were calculated from reference values to determine CED, Krishnan and colleagues reported.
The median radiation dose among the patients included in the analysis was 0.72 mSv (IQR 0.02-4.08 mSv) over a 5-year period. Higher APACHE 3 scores (P<0.001), hepatic failure (P=0.03), and gastrointestinal (GI) disorders were all predictive of higher CED in multiple linear regression modeling.
The odds of receiving a radiation dose of ≥50 mSv was highest in patients with GI bleeding (OR 8.90, 95% CI 6.84-11.59), followed by GI disorders (OR 2.60, 95% CI 2.17-4.04) and hematological disorders (OR 3.58, 95% CI 2.69-4.78).
Krishnan said while the radiation exposures may not be a cause for concern in older, sicker patients, younger patients who survive the ICU may have a greatly elevated risk for cancer from repeated imaging performed during their stay.
Robert Hyzy, MD, of the Clinical Care Medicine Unit at the University of Michigan Hospital in Ann Arbor, told MedPage Today that the study was provocative.
“There is great emphasis on avoiding unnecessary tests, and that extends to the ICU,” said Hyzy, who was not involved in the study. “We can’t really say if we are hurting people over the trajectory of their lives — that is beyond the scope of what this study looked at. But it is certainly food for thought.”
Krishnan and co-authors disclosed no relevant relationships with industry.