The Sicker You Are, the More You Glow - Predictors and Characteristics of Cumulative Radiation Dose Exposure Estimates in the Critically Ill Medical Patient

SESSION TITLE: Hot Topics in Critical Care SESSION TYPE: Original Investigation Slide PRESENTED ON: Sunday, October 25, 2015 at 04:30 PM - 05:30 PM PURPOSE: Critically ill patients are often subjected to multiple radiation based diagnostic studies. Its purported safety and stochastic effects continue to be a cause of concern and scientific debate. Patients experiencing these doses are rarely dose tracked or monitored. We examined the use of diagnostic imaging and cumulative radiation exposure thereof in critically ill patients admitted to a tertiary care Medical Intensive care Unit (MICU) during a single ICU admission. We hypothesized that the patients could be exposed to radiation doses that far exceed the occupational federal limits for US radiation workers (≥50 millisievert (mSv)/year) and would increase with the increasing severity of illness. METHODS: All consecutive MICU admissions (N=4156) admitted to 68 bedded MICU for the year 2013 were identified retrospectively. Dose estimates were calculated for each study (Procedures, CT scans, nuclear scans and plain films) in mSv based on reported dose length products, published reference values, conversion factors and were cumulated. Patient medical records were reviewed for demographics, apache scores, length of stay and associated comorbidities. Univariate and multivariate linear regressions were employed as appropriate. RESULTS: Two percent (N=98) of the 84% of MICU admissions were exposed to radiation doses > 50 mSv. Two percent of patients (N=12) under the age of 40 exceeded the aforesaid dose. 57% of the total radiation dose in the MICU was accrued form CT scanning and 28% from interventional radiology procedures. 13 patients accrued doses > 100mSv. APACHE 3 scores (p<0.0001), Length of MICU stay (p<0.0001), readmission to the MICU (p<0.005) and Diagnosis of Cirrhosis (p<0.0001) were significant for their association with increased radiation dose in a multivariable linear regression model. The mean dose estimate was 7.5 mSv (SD 15.0) with a range of 0 to 176 mSv. CONCLUSIONS: Radiation levels in the critically ill could exceed occupational standards and increase with increasing severity of illness. CT imaging contributes to more than half of the observed exposure in the MICU. Judicious and prudent use of radiologcal studies is imperative. CLINICAL IMPLICATIONS: Critically ill young patients could be exposed to levels of radiation dose that far exceed occupational heath standards, during a single ICU admission. Doses should be tracked and monitored. Alternative forms of imaging (non-radiation based) as well protocols to keep the radiation expsoure to as low as reasonably achievable should be de rigeur. DISCLOSURE: The following authors have nothing to disclose: Sudhir Krishnan, Jagdeesh Yella, Shraddha Narechania, Atul Mehta, Fatima Adhi, Frank Dong, Anil Vijayan, Ajit Moghekar, Xiaofeng Wang, Katrina Zell, Ruchi Yadav, Jorge Guzman No Product/Research Disclosure Information