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Prevalence and Risk Factors for Development of Delirium in Surgical and Trauma Intensive Care Unit Patients

Pandharipande, Pratik MD, MSCI; Cotton, Bryan A. MD, FACS; Shintani, Ayumi PhD, MPH; Thompson, Jennifer MPH; Pun, Brenda Truman MSN, ACNP; Morris, John A. Jr MD, FACS; Dittus, Robert MD, MPH; Ely, E Wesley MD, MPH

The Journal of Trauma: Injury, Infection, and Critical Care: July 2008 - Volume 65 - Issue 1 - p 34-41
doi: 10.1097/TA.0b013e31814b2c4d
Original Articles

Background: Although known to be an independent predictor of poor outcomes in medical intensive care unit (ICU) patients, limited data exist regarding the prevalence of and risk factors for delirium among surgical (SICU) and trauma ICU (TICU) patients. The purpose of this study was to analyze the prevalence of and risk factors for delirium in surgical and trauma ICU patients.

Methods: SICU and TICU patients requiring mechanical ventilation (MV) >24 hours were prospectively evaluated for delirium using the Richmond Agitation Sedation Scale (RASS) and the Confusion Assessment Method for the ICU (CAM-ICU). Those with baseline dementia, intracranial injury, or ischemic/hemorrhagic strokes that would confound the evaluation of delirium were excluded. Markov models were used to analyze predictors for daily transition to delirium.

Results: One hundred patients (46 SICU and 54 TICU) were enrolled. Prevalence of delirium was 73% in the SICU and 67% in the TICU. Multivariable analyses identified midazolam [OR 2.75 (CI 1.43–5.26, p = 0.002)] exposure as the strongest independent risk factor for transitioning to delirium. Opiate exposure showed an inconsistent message such that fentanyl was a risk factor for delirium in the SICU (p = 0.007) but not in the TICU (p = 0.936), whereas morphine exposure was associated with a lower risk of delirium (SICU, p = 0.069; TICU p = 0.024).

Conclusion: Approximately 7 of 10 SICU and TICU patients experience delirium. In keeping with other recent data on benzodiazepines, exposure to midazolam is an independent and potentially modifiable risk factor for the transitioning to delirium.

From the Department of Anesthesia/Critical Care Medicine (P.P), Department of Medicine, Division of General Internal Medicine and Center for Health Services Research and the VA Tennessee Valley Geriatric Research, Education and Clinical Center (R.D., E.W.E.), and Division of Allergy/Pulmonary/Critical Care Medicine (B.T.P., E.W.E.), Department of Biostatistics (A.S., J.T.), Department of Surgery/Division of Trauma, Emergency Surgery, and Surgical Critical Care (B.A.C., J.A.M.), Vanderbilt University School of Medicine, Nashville, Tennessee.

Submitted for publication April 3, 2007.

Accepted for publication July 2, 2007.

The funding agencies had no role in the design or conduct of the study, data collection, management, analysis or interpretation of the data. In addition, they had no role in the preparation, review, or approval of the manuscript.

Dr. Pandharipande is the recipient of the Vanderbilt Physician Scientist Development Award and the ASCCA-FAER Research Grant.

Dr. Ely is the Associate Director of Research for the VA Tennessee Valley Geriatric Research and Education Clinical Center. He is a recipient of the Paul Beeson Faculty Scholar Award from the Alliance for Aging Research and is a recipient of a K23 from the National Institute of Health (#AG01023-01A1), an RO-1 from the National Institute of Aging (#AG0727201-A1), and a VA MERIT Award from CSRND.

Address for reprints: Bryan A. Cotton, MD, FACS, Division of Trauma/Surgical Critical Care, 1121st Avenue South, 404 Medical Arts Building, Nashville, TN 37212; email:

© 2008 Lippincott Williams & Wilkins, Inc.