Radiation for Intoxication?
The Case for Reducing CT Use in Inebriated Patients Lacking Evidence of Trauma.
CASE
History:
20 yo unidentified M is brought to the ED by EMS after bystanders found him unresponsive in an alleyway. Concern for alcohol intoxication.
Patient unable to provide history or ROS due to AMS apparently 2/2 intoxication.
Physical Exam:
Vitals on arrival: BP 112/61, HR 97, T 36.5°C, RR 19, SpO2 98% on RA
Patient appears disheveled and intoxicated
GCS 14, PERRL, follows commands, moves all extremities equally and spontaneously
Cardiovascular, pulmonary, abdominal, and HEENT exams benign
No visible signs of head trauma
ED Management:
EtOH level – 347
CBC, CMP, lactate unremarkable
Transaminitis: AST - 249, ALT – 253
CT Head/Brain w/o contrast and CT C-spine w/o contrast - no acute or subacute intracranial or cervical spine abnormalities
Patient left the ED AMA after achieving clinical sobriety
Relevant Context:
Between 6/7/2022 and 7/7/2022 this patient had 17 separate ED presentations for alcohol intoxication. Each time, he left the department against medical advice after becoming clinically sober.
During this one-month period, he received 7 CT scans of his head/ neck for AMS and an unclear trauma history.
Clinical Question:
For patients who present frequently to the ED with alcohol intoxication, what head imaging protocols should we follow to maximize clinical value while minimizing patient risk and radiation exposure?
SUMMARY OF EVIDENCE
Point 1: Alcohol intoxication increases the likelihood that we use head imaging in the ED
This should be intuitive – intoxicated patients are less likely to provide us with pertinent clinical history used to rule out head imaging. Indeed, some clinical decision-making tools, such as the New Orleans Rule, explicitly necessitate CT in head injury patients with alcohol intoxication.
The odds of an intoxicated trauma patient receiving a head CT are 2.34 those of a non-intoxicated trauma patient, even when controlling for other factors7. In a retrospective study of 214 consecutive patients presenting to an urban, level 1 trauma center with activation of the trauma team, Weber et al. (2019) found that alcohol intoxication (defined as BAC > 0.08 on arrival) was the second-best independent predictor for getting a head CT (OR 2.34; 95% CI 1.096-5.001). The only parameter that better predicted head imaging was a known head injury with AIS ≥ 3 (OR 3.44; 95% CI 1.363-8.675).
Point 2: The yield for head imaging in intoxicated patients with minor head trauma is low
Very few patients who present with alcohol intoxication are found to have a head bleed on CT1. Godbout et al. (2011) conducted a retrospective chart review of patients who presented to the ED with a chief complaint of alcohol intoxication and also received a head CT. 2,671 such patients were identified over a four-year period in an inner-city academic center. The authors found that 50 (1.87%) of those patients had a positive CT, defined as evidence of an intracranial hemorrhage (ICH). Importantly, this study did not attempt to determine the clinical significance of these hemorrhages – likely making the number of positive CTs that required intervention or changed management even lower.
Of the 50 most common chief complaints leading to CT head exams, alcohol intoxication had the second lowest yield (2.5%)7. Tu et al. (2022) conducted a retrospective study of 708,145 ED encounters at an academic medical center over a four-year period. 58,783 CT head exams were performed and the rate of positive results (defined as critical results requiring non-routine communication from radiology) were compared between the 50 most common chief complaints.
Physicians are effective at clinically determining which patients presenting with alcohol intoxication are low risk4. In a retrospective observational study over a five-year period, Klein et al. (2018) examined 31,364 patient encounters for alcohol intoxication deemed to be low risk for critical illness. Of these encounters, 325 (1%) required activation of critical care resources for any reason (defined as evaluation of the patient in a critical care bay or admission to the ICU) – of note, 148 of these activations were for alcohol withdrawal symptoms. 32 patients (0.1%) were found to have an ICH.
Point 3: Unnecessary head imaging in intoxicated patients is not benign
Patients with frequent ED visits (>3 visits per year) who undergo repeated CT scans accumulate, on average, 122 mSv of radiation and incur a 1 in 82 lifetime attributable cancer risk2. Over a 7.7-year period, Griffey et al. (2009) conducted a retrospective analysis of all patients who presented to the emergency department of an academic, tertiary care center at least 3 times per year. In this population, they calculated median, mean, and maximum cumulative radiation doses from CT – 91, 122, and 597 mSv, respectively. They then used a population-averaged dose-risk conversion factor (one cancer per 1,000 patients receiving 10-mSv dose) to calculate median, mean, and maximum lifetime attributable risk of cancer development – 1 in 110, 1 in 82, and 1 in 17, respectively in this population.
RECOMMENDATIONS
Regardless of intoxication or prior ED presentations, any patient presenting to the ED with AMS and an unknown trauma history warrants a careful clinical evaluation and consideration of imaging to rule out ICH.
Alcohol intoxication alone should not be an indication for head CT – it is low yield and confers real risk to patients over extended periods of time.
Frequent ED presentations for AMS in the setting of intoxication should be noted and utilized as important clinical context to decrease the frequency of head imaging in this patient population.
REFERENCES
1) Godbout, B.J., Lee, J., Newman, D.H. et al. Yield of head CT in the alcohol-intoxicated patient in the emergency department. Emerg Radiol 18, 381–384 (2011).
2) Griffey, R.T., Stodickson, A. Cumulative Radiation Exposure and Cancer Risk Estimates in Emergency Department Patients Undergoing Repeat or Multiple CT. American Journal of Roetgenology, 192, 4 (2009).
3) Hamilton, B.H, Sheth, A., McCormack, R.T., McCormack, R. P. Imaging of Frequent Emergency Department Users with Alcohol Use Disorders. J Emergency Medicine 46, 582-587 (2014).
4) Klein, L.R., Cole J.B., Driver, B.E. et al. Unsuspected Critical Illness Among Emergency Department Patients Presenting for Acute Alcohol Intoxication. Annals of Emergency Medicine 71, 279-288 (2018).
5) LaCalle E, Rabin E. Frequent users of emergency departments: the myths, the data, and the policy implications. Ann Emerg Med. (2010).
6) Sperry JL, Gentilello LM, Minei JP, Diaz-Arrastia RR, Friese RS, Shafi S. Waiting for the patient to "sober up": Effect of alcohol intoxication on glasgow coma scale score of brain injured patients. J Trauma (2006).
7) Tu, L.H., Venkatesh, A.K., Malhotra, A. et al. Scenarios to improve CT head utilization in the emergency department delineated by critical results reporting. Emerg Radiol 29, 81–88 (2022).
8) Weber, C.D., Schmitz, J.K., Garving, C. et al. The alcohol-intoxicated trauma patient: impact on imaging and radiation exposure. Eur J Trauma Emerg Surg 45, 871–876 (2019).
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