Heart rate variability in intensive care unit patients with delirium

Sympathovagal balance, assessed with heart rate variability (HRV), may be altered in intensive care unit (ICU) delirium. HRV was measured in the frequency domain [low frequencies (LF)=0.04-0.15 Hz and high frequencies (HF)=0.15-0.40 Hz] with HF in normalized units (HFnu) to evaluate parasympathetic tone and LF:HF ratio for sympathovagal balance. The authors assessed 726 ICU patients and excluded patients with conditions affecting HRV. No difference could be found between patients with (N=13) and without (N=12) delirium by comparing the mean (±standard deviation) of the HFnu (75±7 versus 68±23) and the LF:HF ratio (-0.7±1.0 versus -0.1±1.1). This study suggests that autonomic function is not altered in ICU delirium

Systemic Corticosteroids and Transition to Delirium in Critically Ill Patients

OBJECTIVE: Corticosteroids are frequently used in critically ill patients. We investigated whether systemic corticosteroid use increases the probability of transitioning to delirium in a large population of mixed medical-surgical ICU patients. DESIGN: Prospective cohort study. SETTING: A 32-bed medical-surgical ICU at an academic medical center. PATIENTS: Critically ill adults (n = 1,112), admitted to the ICU for more than 24 hours without a condition that could hamper delirium assessment. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Systemic corticosteroid exposure was measured daily and converted to prednisone equivalents (milligrams). Daily mental status was classified as coma, delirium, or an awake without delirium state. Transitions between states were analyzed using a first-order Markov multinomial logistic regression model with 11 different covariables, with the transition from an awake without delirium state to delirium as a primary interest. Among the 1,112 patients, corticosteroids were administered on 35% (3,483/9,867) of the ICU days at a median dose of 50 mg (interquartile range, 25-75 mg) prednisone equivalent. Administration of a corticosteroid, and any increase in the dose of the corticosteroid given on exposure days, was not significantly associated with the transition to delirium (adjusted odds ratio, 1.08; 95% CI, 0.89-1.32 and adjusted odds ratio, 1.00; 95% CI, 0.99-1.01, per 10 mg increase in prednisone equivalent). CONCLUSIONS: In a large population of mixed medical-surgical ICU patients, systemic corticosteroid use was not associated with an increased probability of transitioning to delirium