Acute Brain Dysfunction: Development and Validation of a Daily Prediction Model.

BACKGROUND: The goal of this study was to develop and validate a dynamic risk model to predict daily changes in acute brain dysfunction (ie, delirium and coma), discharge, and mortality in ICU patients. METHODS: Using data from a multicenter prospective ICU cohort, a daily acute brain dysfunction-prediction model (ABD-pm) was developed by using multinomial logistic regression that estimated 15 transition probabilities (from one of three brain function states [normal, delirious, or comatose] to one of five possible outcomes [normal, delirious, comatose, ICU discharge, or died]) using baseline and daily risk factors. Model discrimination was assessed by using predictive characteristics such as negative predictive value (NPV). Calibration was assessed by plotting empirical vs model-estimated probabilities. Internal validation was performed by using a bootstrap procedure. RESULTS: Data were analyzed from 810 patients (6,711 daily transitions). The ABD-pm included individual risk factors: mental status, age, preexisting cognitive impairment, baseline and daily severity of illness, and daily administration of sedatives. The model yielded very high NPVs for "next day" delirium (NPV: 0.823), coma (NPV: 0.892), normal cognitive state (NPV: 0.875), ICU discharge (NPV: 0.905), and mortality (NPV: 0.981). The model demonstrated outstanding calibration when predicting the total number of patients expected to be in any given state across predicted risk. CONCLUSIONS: We developed and internally validated a dynamic risk model that predicts the daily risk for one of three cognitive states, ICU discharge, or mortality. The ABD-pm may be useful for predicting the proportion of patients for each outcome state across entire ICU populations to guide quality, safety, and care delivery activities.

Sedative Plasma Concentrations and Delirium Risk in Critical Illness.

BACKGROUND: The relationship between plasma concentration of sedatives and delirium is unknown. OBJECTIVE: We hypothesized that higher plasma concentrations of lorazepam are associated with increased delirium risk, whereas higher plasma concentrations of dexmedetomidine are associated with reduced delirium risk. METHODS: This prospective cohort study was embedded in a double-blind randomized clinical trial, where ventilated patients received infusions of lorazepam and dexmedetomidine. Plasma concentrations of these drugs and delirium assessments were measured at least daily. A multivariable logistic regression model accounting for repeated measures was used to analyze associations between same-day plasma concentrations of lorazepam and dexmedetomidine (exposures) and the likelihood of next-day delirium (outcome), adjusting for same-day mental status (delirium, coma, or normal) and same-day fentanyl doses. RESULTS: This critically ill cohort (n = 103) had a median age of 60 years (IQR: 48-66) with APACHE II score of 28 (interquartile range [IQR] = 24-32), where randomization resulted in assignment to lorazepam (n = 51) or dexmedetomidine (n = 52). After adjusting for same-day fentanyl dose and mental status, higher plasma concentrations of lorazepam were associated with increased probability of next-day delirium (comparing 500 vs 0 ng/mL; odds ratio [OR] = 13.2; 95% CI = 1.4-120.1; P = 0.02). Plasma concentrations of dexmedetomidine were not associated with next-day delirium (comparing 1 vs 0 ng/mL; OR = 1.1; 95% CI = 0.9-1.3; P = 0.45). CONCLUSIONS: In critically ill patients, higher lorazepam plasma concentrations were associated with delirium, whereas dexmedetomidine plasma concentrations were not. This implies that the reduced delirium risk seen in patients sedated with dexmedetomidine may be a result of avoidance of benzodiazepines, rather than a dose-dependent protective effect of dexmedetomidine.

Evaluation of a Prediction Model for the Development of Atrial Fibrillation in a Repository of Electronic Medical Records.

IMPORTANCE: Atrial fibrillation (AF) contributes to substantial morbidity, mortality, and health care expenditures. Accurate prediction of incident AF would enhance AF management and potentially improve patient outcomes. OBJECTIVE: To validate the AF risk prediction model originally developed by the Cohorts for Heart and Aging Research in Genomic Epidemiology-Atrial Fibrillation (CHARGE-AF) investigators using a large repository of electronic medical records (EMRs). DESIGN, SETTING, AND PARTICIPANTS: In this prediction model study, deidentified EMRs of 33 494 individuals 40 years or older who were white or African American and had no history of AF were reviewed and analyzed. The participants were followed up in the internal medicine outpatient clinics at Vanderbilt University Medical Center for incident AF from December 31, 2005, until December 31, 2010. Adjusting for differences in baseline hazard, the CHARGE-AF Cox proportional hazards model regression coefficients were applied to the EMR cohort. A simple version of the model with no echocardiographic variables was also evaluated. Data were analyzed from October 31, 2013, to January 31, 2014. MAIN OUTCOMES AND MEASURES: Incident AF. Predictors in the model included age, race, height, weight, systolic and diastolic blood pressure, treatment for hypertension, smoking status, type 2 diabetes, heart failure, history of myocardial infarction, left ventricular hypertrophy, and PR interval. RESULTS: Among the 33 494 participants, the median age was 57 (interquartile range, 49-67) years; 57% of patients were women, 43% were men, 85.7% were white, and 14.3% were African American. During the mean (SD) follow-up of 4.8 (0.9) years, 2455 individuals (7.3%) developed AF. Both models had poor calibration in the EMR cohort, with underprediction of AF among low-risk individuals and overprediction of AF among high-risk individuals (10th and 90th percentiles for predicted probability of incident AF, 0.005 and 0.179, respectively). The full CHARGE-AF model had a C index of 0.708 (95% CI, 0.699-0.718) in our cohort. The simple model had similar discrimination (C index, 0.709; 95% CI, 0.699-0.718; P = .70 for difference between models). CONCLUSIONS AND RELEVANCE: Despite reasonable discrimination, the CHARGE-AF models showed poor calibration in this EMR cohort. This study highlights the difficulties of applying a risk model derived from prospective cohort studies to an EMR cohort and suggests that these AF risk prediction models be used with caution in the EMR setting. Future risk models may need to be developed and validated within EMR cohorts.

Functional brain imaging in survivors of critical illness: A prospective feasibility study and exploration of the association between delirium and brain activation patterns.

PURPOSE: We undertook this pilot prospective cohort investigation to examine the feasibility of functional magnetic resonance imaging (fMRI) assessments in survivors of critical illness and to analyze potential associations between delirium and brain activation patterns observed during a working memory task (N-back) at hospital discharge and 3-month follow-up. MATERIALS AND METHODS: At hospital discharge and 3 months later, fMRI assessed subjects' functional activity during an N-back task. Multiple linear regression was used to examine associations between duration of delirium and brain activity, and elastic net regression was used to assess the relationship between brain activation patterns at 3 months and cognitive outcomes at 12 months. RESULTS: Of 47 patients who underwent fMRI at discharge, 38 (80%) completed the protocol; of 37 who underwent fMRI at 3 months, 34 (91%) completed the protocol. At discharge, the mean (SD) percentage of correct responses on the most challenging version (the N2 version) of the N-back task was 70.4 (23.2; range of 20-100) compared with 76 (23.4; range of 33-100) at 3 months. No association was observed between delirium duration in the hospital and brain region activity in any brain region at discharge or 3 months after adjusting for relevant covariates (P values across all 11 brain regions of interest were >.25). CONCLUSIONS: Our data support the feasibility of using fMRI in survivors of critical illness at 3-month follow-up but not at discharge. In this small study, delirium was not associated with distinct or abnormal brain activation patterns, although overall performance on a cognitive task of working memory was poorer than observed in other cohorts of individuals with medically related executive dysfunction, mild cognitive impairment, and mild traumatic brain injury.

Urinary L-FABP predicts poor outcomes in critically ill patients with early acute kidney injury.

Biomarker studies for early detection of acute kidney injury (AKI) have been limited by nonselective testing and uncertainties in using small changes in serum creatinine as a reference standard. Here we examine the ability of urine L-type fatty acid-binding protein (L-FABP), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), and kidney injury molecule-1 (KIM-1) to predict injury progression, dialysis, or death within 7 days in critically ill adults with early AKI. Of 152 patients with known baseline creatinine examined, 36 experienced the composite outcome. Urine L-FABP demonstrated an area under the receiver-operating characteristic curve (AUC-ROC) of 0.79 (95% confidence interval 0.70-0.86), which improved to 0.82 (95% confidence interval 0.75-0.90) when added to the clinical model (AUC-ROC of 0.74). Urine NGAL, IL-18, and KIM-1 had AUC-ROCs of 0.65, 0.64, and 0.62, respectively, but did not significantly improve discrimination of the clinical model. The category-free net reclassification index improved with urine L-FABP (total net reclassification index for nonevents 31.0%) and urine NGAL (total net reclassification index for events 33.3%). However, only urine L-FABP significantly improved the integrated discrimination index. Thus, modest early changes in serum creatinine can help target biomarker measurement for determining prognosis with urine L-FABP, providing independent and additive prognostic information when combined with clinical predictors.

Statins and delirium during critical illness: a multicenter, prospective cohort study.

OBJECTIVE: Since statins have pleiotropic effects on inflammation and coagulation that may interrupt delirium pathogenesis, we tested the hypotheses that statin exposure is associated with reduced delirium during critical illness, whereas discontinuation of statin therapy is associated with increased delirium. DESIGN: Multicenter, prospective cohort study. SETTING: Medical and surgical ICUs in two large tertiary care hospitals in the United States. PATIENTS: Patients with acute respiratory failure or shock. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We measured statin exposure prior to hospitalization and daily during the ICU stay, and we assessed patients for delirium twice daily using the Confusion Assessment Method for the ICU. Of 763 patients included, whose median (interquartile range) age was 61 years (51-70 yr) and Acute Physiology and Chronic Health Evaluation II was 25 (19-31), 257 (34%) were prehospital statin users and 197 (26%) were ICU statin users. Overall, delirium developed in 588 patients (77%). After adjusting for covariates, ICU statin use was associated with reduced delirium (p < 0.01). This association was modified by sepsis and study day; for example, statin use was associated with reduced delirium among patients with sepsis on study day 1 (odds ratio, 0.22; 95% CI, 0.10-0.49) but not among patients without sepsis on day 1 (odds ratio, 0.92; 95% CI, 0.46-1.84) or among those with sepsis later, for example, on day 13 (odds ratio, 0.70; 95% CI, 0.35-1.41). Prehospital statin use was not associated with delirium (odds ratio, 0.86; 95% CI, 0.44-1.66; p = 0.18), yet the longer a prehospital statin user's statin was held in the ICU, the higher the odds of delirium (overall p < 0.001 with the odds ratio depending on sepsis status and study day due to significant interactions). CONCLUSIONS: In critically ill patients, ICU statin use was associated with reduced delirium, especially early during sepsis; discontinuation of a previously used statin was associated with increased delirium.

Depression, post-traumatic stress disorder, and functional disability in survivors of critical illness in the BRAIN-ICU study: a longitudinal cohort study.

BACKGROUND: Critical illness is associated with cognitive impairment, but mental health and functional disabilities in survivors of intensive care are inadequately characterised. We aimed to assess associations of age and duration of delirium with mental health and functional disabilities in this group. METHODS: In this prospective, multicentre cohort study, we enrolled patients with respiratory failure or shock who were undergoing treatment in medical or surgical ICUs in Nashville, TN, USA. We obtained data for baseline demographics and in-hospital variables, and assessed survivors at 3 months and 12 months with measures of depression (Beck Depression Inventory II), post-traumatic stress disorder (PTSD, Post-Traumatic Stress Disorder Checklist-Event Specific Version), and functional disability (activities of daily living scales, Pfeffer Functional Activities Questionnaire, and Katz Activities of Daily Living Scale). We used linear and proportional odds logistic regression to assess the independent associations between age and duration of delirium with mental health and functional disabilities. This study is registered with ClinicalTrials.gov, number NCT00392795. FINDINGS: We enrolled 821 patients with a median age of 61 years (IQR 51-71), assessing 448 patients at 3 months and 382 patients at 12 months after discharge. At 3 months, 149 (37%) of 406 patients with available data reported at least mild depression, as did 116 (33%) of 347 patients at 12 months; this depression was mainly due to somatic rather than cognitive-affective symptoms. Depressive symptoms were common even among individuals without a history of depression (as reported by a proxy), occurring in 76 (30%) of 255 patients with data at 3 months and 62 (29%) of 217 individuals at 12 months. Only 7% of patients (27 of 415 at 3 months and 24 of 361 at 12 months) had symptoms consistent with post-traumatic distress disorder. Disabilities in basic activities of daily living (ADL) were present in 139 (32%) of 428 patients at 3 months and 102 (27%) of 374 at 12 months, as were disabilities in instrumental ADL in 108 (26%) of 422 individuals at 3 months and 87 (23%) of 372 at 12 months. Mental health and functional difficulties were prevalent in patients of all ages. Although old age was frequently associated with mental health problems and functional disabilities, we observed no consistent association between the presence of delirium and these outcomes. INTERPRETATION: Poor mental health and functional disability is common in patients treated in intensive-care units. Depression is five times more common than is post-traumatic distress disorder after critical illness and is driven by somatic symptoms, suggesting approaches targeting physical rather than cognitive causes could benefit patients leaving critical care. FUNDING: National Institutes of Health AG027472 and the Geriatric Research, Education and Clinical Center (GRECC), Department of Veterans Affairs Medical Center, Tennessee Valley Healthcare System.

Brief report: Risk of adverse fetal outcomes associated with immunosuppressive medications for chronic immune-mediated diseases in pregnancy.

OBJECTIVE: To assess the risk of adverse fetal outcomes following exposure to individual immunosuppressive drugs in pregnant women with chronic immune-mediated diseases. METHODS: Health plan data were obtained from the Tennessee Medicaid and Kaiser Permanente Northern California and Southern California claims databases, with linkage to both vital records and medical records. Women with inflammatory arthropathies, those with systemic lupus erythematosus, and those with inflammatory bowel disease who filled prescriptions for immunosuppressive treatments during pregnancy were included. Major congenital malformations, fetal deaths, and life-threatening neonatal complications were identified from the electronic data and validated with medical record review. RESULTS: The cohort included 608 infants, including 437 with exposure to immunosuppressive drugs during the mother's pregnancy (402 during the first trimester, and 35 during the second and third trimester only) and 171 whose mothers filled prescriptions for immunosuppressive treatments before, but not during, pregnancy. There were 25 pregnancies (4.1% of the cohort) with confirmed major congenital malformations, and 10 fetal deaths (1.6% of the cohort). Among 113 preterm infants with exposures during pregnancy, 23 (20.4%) had life-threatening neonatal complications, and among 485 term infants, 10 (2.1%) had life-threatening complications. Compared to the reference group (treatment before, but not during, pregnancy), the risk ratios (RRs) for adverse fetal outcomes associated with immunosuppressive treatments (by exposure category) during pregnancy included the following: methotrexate (RR 1.39, 95% confidence interval [95% CI] 0.43-4.53), tumor necrosis factor inhibitors (RR 0.98, 95% CI 0.38-2.55), hydroxychloroquine (RR 1.33, 95% CI 0.69-2.55), and other immunosuppressive medications (RR 0.98, 95% CI 0.48-1.98). CONCLUSION: In this study, there was no evidence of a large increase in risk of adverse fetal outcomes from first-trimester exposure to immunosuppressive medications, although the confidence intervals for the risk ratios were wide. Further studies will be needed as use of these medications increases over time.

Delirium in the ICU and subsequent long-term disability among survivors of mechanical ventilation.

OBJECTIVE: Survivors of critical illness are frequently left with long-lasting disability. The association between delirium and disability in critically ill patients has not been described. We hypothesized that the duration of delirium in the ICU would be associated with subsequent disability and worse physical health status following a critical illness. DESIGN: Prospective cohort study nested within a randomized controlled trial of a paired sedation and ventilator weaning strategy. SETTING: A single-center tertiary-care hospital. PATIENTS: One hundred twenty-six survivors of a critical illness. MEASUREMENTS AND MAIN RESULTS: Confusion Assessment Method for the ICU, Katz activities of daily living, Functional Activities Questionnaire (measuring instrumental activities of daily living), Medical Outcomes Study 36-item Short Form General Health Survey Physical Components Score, and Awareness Questionnaire were used. Associations between delirium duration and outcomes were determined via proportional odds logistic regression with generalized estimating equations (for Katz activities of daily living and Functional Activities Questionnaire scores) or via generalized least squares regression (for Medical Outcomes Study 36-item Short Form General Health Survey Physical Components Score and Awareness Questionnaire scores). Excluding patients who died prior to follow-up but including those who withdrew or were lost to follow-up, we assessed 80 of 99 patients (81%) at 3 months and 63 of 87 patients (72%) at 12 months. After adjusting for covariates, delirium duration was associated with worse activities of daily living scores (p = 0.002) over the course of the 12-month study period but was not associated with worse instrumental activities of daily living scores (p = 0.15) or worse Medical Outcomes Study 36-item Short Form General Health Survey Physical Components Score (p = 0.58). Duration of delirium was also associated with lower Awareness Questionnaire Motor/Sensory Factors scores (p 0.02). CONCLUSION: In the setting of critical illness, longer delirium duration is independently associated with increased odds of disability in activities of daily living and worse motor-sensory function in the following year. These data point to a need for further study into the determinants of functional outcomes in ICU survivors.

Inappropriate medication prescriptions in elderly adults surviving an intensive care unit hospitalization.

OBJECTIVES: To determine types of potentially (PIMs) and actually inappropriate medications (AIMs), which PIMs are most likely to be considered AIMs, and risk factors for PIMs and AIMs at hospital discharge in elderly intensive care unit (ICU) survivors. DESIGN: Prospective cohort study. SETTING: Tertiary care, academic medical center. PARTICIPANTS: One hundred twenty individuals aged 60 and older who survived an ICU hospitalization. MEASUREMENTS: Potentially inappropriate medications were defined according to published criteria; a multidisciplinary panel adjudicated AIMs. Medications from before admission, ward admission, ICU admission, ICU discharge, and hospital discharge were abstracted. Poisson regression was used to examine independent risk factors for hospital discharge PIMs and AIMs. RESULTS: Of 250 PIMs prescribed at discharge, the most common were opioids (28%), anticholinergics (24%), antidepressants (12%), and drugs causing orthostasis (8%). The three most common AIMs were anticholinergics (37%), nonbenzodiazepine hypnotics (14%), and opioids (12%). Overall, 36% of discharge PIMs were classified as AIMs, but the percentage varied according to drug type. Whereas only 16% of opioids, 23% of antidepressants, and 10% of drugs causing orthostasis were classified as AIMs, 55% of anticholinergics, 71% of atypical antipyschotics, 67% of nonbenzodiazepine hypnotics and benzodiazepines, and 100% of muscle relaxants were deemed AIMs. The majority of PIMs and AIMs were first prescribed in the ICU. Preadmission PIMs, discharge to somewhere other than home, and discharge from a surgical service predicted number of discharge PIMs, but none of the factors predicted AIMs at discharge. CONCLUSION: Certain types of PIMs, which are commonly initiated in the ICU, are more frequently considered inappropriate upon clinical review. Efforts to reduce AIMs in elderly ICU survivors should target these specific classes of medications.

Atypical sleep in ventilated patients: empirical electroencephalography findings and the path toward revised ICU sleep scoring criteria.

OBJECTIVES: Standard sleep scoring criteria may be unreliable when applied to critically ill patients. We sought to quantify typical and atypical polysomnographic findings in critically ill patients and to begin development and reliability testing of methodology to characterize the atypical polysomnographic tracings that confound standard sleep scoring criteria. DESIGN: Prospective convenience sample. SETTING: Two academic, tertiary care medical centers. PATIENTS: Thirty-seven critically ill, mechanically ventilated, medical ICU patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Mechanically ventilated subjects were monitored by continuous polysomnography. After noting frequent atypical polysomnographic findings (i.e., lack of stage N2 markers, the presence of polymorphic delta, burst suppression, or isoelectric electroencephalography), attempts to use standard sleep scoring criteria alone were abandoned. Atypical polysomnographic findings were characterized and used to develop a modified scoring system. Polysomnographic data were scored manually via this revised scoring scheme. Of 37 medical ICU patients enrolled, 36 experienced atypical sleep, which accounted for 85% of all recorded data, with 5.1% normal sleep and 9.4% wake. Coupling observed patient arousal levels with polysomnographic characteristics revealed that standard polysomnographic staging criteria did not reliably determine the presence or absence of sleep. Rapid eye movement occurred in only five patients (14%). The revised scoring system incorporating frequently seen atypical characteristics yielded very high interrater reliability (weighted κ = 0.80; bootstrapped 95% CI, [0.48, 0.89]). CONCLUSIONS: Analysis of polysomnographic data revealed profound deficiencies in standard scoring criteria due to a predominance of atypical polysomnographic findings in ventilated patients. The revised scoring scheme proved reliable in sleep staging and may serve as a building block in future work.

Fluoroquinolone susceptibility in Mycobacterium tuberculosis after pre-diagnosis exposure to older- versus newer-generation fluoroquinolones.

Fluoroquinolone exposure before tuberculosis (TB) diagnosis is common. We anticipated that exposure to older-generation fluoroquinolones is associated with greater fluoroquinolone MICs in Mycobacterium tuberculosis than exposure to newer agents. A nested case-control study was performed among newly diagnosed TB patients reported to the Tennessee Department of Health (January 2002-December 2009). Each fluoroquinolone-resistant case (n=25) was matched to two fluoroquinolone-susceptible controls (n=50). Ciprofloxacin and ofloxacin were classified as older-generation fluoroquinolones; levofloxacin, moxifloxacin and gatifloxacin were considered newer agents. There was no difference between median ofloxacin MIC for isolates from 9 patients exposed only to older fluoroquinolones, 25 exposed only to newer fluoroquinolones, 6 exposed to both and 35 fluoroquinolone-unexposed patients (Kruskal-Wallis, P=0.35). Using multivariate proportional odds logistic regression adjusting for age and sex, duration of exposure to newer fluoroquinolones was independently associated with higher MIC (OR=1.79, 95% CI 1.22-2.64), but duration of exposure to older fluoroquinolones was not (OR=0.94, 95% CI 0.50-1.78). Isolates from patients exposed only to newer fluoroquinolones tended to have mutations at gyrA codons 90, 91 or 94 more frequently than those exposed only to older fluoroquinolones (44% vs. 11%). We were surprised to find that duration of exposure to newer fluoroquinolones, but not older ones, was independently associated with higher ofloxacin MIC. This suggests that the mutant selection window lower boundary is likely to have clinical relevance; caution is warranted when newer fluoroquinolones are prescribed to patients with TB risk factors.

An association between adiposity and serum levels of macrophage inflammatory protein-1α and soluble CD14 in HIV-infected adults: results from a cross-sectional study.

BACKGROUND: Greater adipose tissue is associated with increased circulating high-sensitivity C-reactive protein (hsCRP) levels in HIV-infected adults on antiretroviral therapy (ART), but the relationship between adiposity and other inflammation biomarkers is not well-characterized. METHODS: We measured total and regional adipose tissue deposits using dual energy X-ray absorptiometry (DXA) and serum levels of interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) receptor 1 and 2, macrophage inflammatory protein-1α (MIP-1α), macrophage chemotactic protein-1 (MCP-1), soluble CD14 and hsCRP in a cohort of adults on long-term ART. Regression models were adjusted for age, sex, CD4(+) T-cell count, smoking status, protease-inhibitor-use and daily use of either non-steroidal anti-inflammatory drugs or aspirin. RESULTS: The majority (77%) of the 85 study participants were male, median CD4(+) T-cell count was 500 cells/µl (IQR 315-734) and median BMI was 25.1 kg/m(2) (IQR 22.7-28.1). DXA measurements of total fat mass were positively associated with serum hsCRP (ß=1.82, P<0.01) and MIP-1α (ß=1.36, P<0.01), but negatively associated with soluble CD14 (ß=0.90, P<0.01). Results were similar for trunk fat, limb fat and serum leptin level. The positive relationship between DXA measurements and TNF-α receptor 1 approached significance (P≤0.07 for all). There was no consistent relationship between adiposity and serum IL-6, TNF-α receptor 2 or MCP-1 levels. CONCLUSIONS: Total and regional adiposity was associated with serum hsCRP, but not other inflammatory cytokines shown to predict morbidity and mortality in treated HIV. Greater adiposity is associated with higher MIP-1α and lower soluble CD14 levels, possibly reflecting an important role for cells of the monocyte/macrophage lineage.

Delirium in the cardiovascular ICU: exploring modifiable risk factors.

OBJECTIVE: Delirium, an acute organ dysfunction, is common among critically ill patients leading to significant morbidity and mortality; its epidemiology in a mixed cardiology and cardiac surgery ICU is not well established. We sought to determine the prevalence and risk factors for delirium among cardiac surgery ICU patients. DESIGN: Prospective observational study. SETTING: Twenty-seven-bed medical-surgical cardiac surgery ICU. PATIENTS: Two hundred consecutive patients with an expected cardiac surgery ICU length of stay >24 hrs. INTERVENTIONS: None. MEASUREMENTS: Baseline demographic data and daily assessments for delirium using the validated and reliable Confusion Assessment Method for the ICU were recorded, and quantitative tracking of delirium risk factors were conducted. Separate analyses studied the role of admission risk factors for occurrence of delirium during the cardiac surgery ICU stay and identified daily occurring risk factors for the development of delirium on a subsequent cardiac surgery ICU day. MAIN RESULTS: Prevalence of delirium was 26%, similar among cardiology and cardiac surgical patients. Nearly all (92%) exhibited the hypoactive subtype of delirium. Benzodiazepine use at admission was independently predictive of a three-fold increased risk of delirium (odds ratio 3.1 [1, 9.4], p = 0.04) during the cardiac surgery ICU stay. Of the daily occurring risk factors, patients who received benzodiazepines (2.6 [1.2, 5.7], p = 0.02) or had restraints or devices that precluded mobilization (2.9 [1.3, 6.5], p < 0.01) were more likely to have delirium the following day. Hemodynamic status was not associated with delirium. CONCLUSIONS: Delirium occurred in one in four patients in the cardiac surgery ICU and was predominately hypoactive in subtype. Chemical restraints via use of benzodiazepines or the use of physical restraints/restraining devices predisposed patients to a greater risk of delirium, pointing to areas of quality improvement that would be new to the vast majority of cardiac surgery ICUs.

Association between endothelial dysfunction and acute brain dysfunction during critical illness.

BACKGROUND: Acute brain dysfunction (delirium and coma) during critical illness is prevalent and costly, but the pathophysiology remains unclear. The relationship of acute brain dysfunction with endothelial function, which is impaired in critical illness and may contribute to alterations in cerebral blood flow and blood-brain barrier permeability, has not been studied. This study sought to determine whether systemic endothelial dysfunction is associated with acute brain dysfunction during critical illness. METHODS: In this prospective cohort study, adult medical/surgical intensive care unit patients in shock and/or respiratory failure were enrolled. Endothelial function was assessed at enrollment using peripheral artery tonometry to calculate the reactive hyperemia index, with lower reactive hyperemia index indicative of worse endothelial function. Patients were assessed for coma and delirium with the Richmond Agitation-Sedation Scale and Confusion Assessment Method for the Intensive Care Unit. Multivariable linear regression was used to analyze the association between reactive hyperemia index and (1) delirium/coma-free days among all patients and (2) delirium duration among survivors, both over a 14-day period. RESULTS: One hundred forty-seven patients with median age of 57 yr and median Acute Physiology and Chronic Health Evaluation II score of 26 were enrolled. After adjusting for age, severity of illness, severe sepsis, preexisting cognitive function, medical versus surgical intensive care unit admission, and prehospital statin use, lower reactive hyperemia index (worse systemic endothelial function) was associated with fewer delirium/coma-free days (P = 0.02) and more delirium days (P = 0.05). CONCLUSIONS: In this study, critically ill patients with lower vascular reactivity indicative of worse systemic endothelial function had increased duration of acute brain dysfunction.

Associations of markers of inflammation and coagulation with delirium during critical illness.

PURPOSE: To assess the associations between a priori-selected markers of inflammation and coagulation and delirium during critical illness. METHODS: In this prospective cohort study, we collected blood from mechanically ventilated medical intensive care unit (ICU) patients and measured nine plasma markers of inflammation and coagulation. We assessed patients daily for delirium using the Confusion Assessment Method for the ICU and used multivariable regression to analyze the associations between plasma markers and subsequent delirium, after adjusting for age, severity of illness, and sepsis. RESULTS: Among the 138 patients studied, with median age of 66 years and median Acute Physiology and Chronic Health Evaluation (APACHE) II of 27, 107 (78 %) were delirious at some point during the study. Two markers of inflammation and one of coagulation were significantly associated with delirium. After adjusting for covariates, lower plasma concentrations of matrix metalloproteinase-9 (MMP-9) and protein C were associated with increased probability of delirium (p = 0.04 and 0.01, respectively), and higher concentrations of soluble tumor necrosis factor receptor-1 (sTNFR1) were associated with increased probability of delirium (p < 0.01). Concentrations of C-reactive protein (p = 0.82), myeloperoxidase (p = 0.11), neutrophil gelatinase-associated lipocalin (p = 0.70), D-dimer (p = 0.83), plasminogen activator inhibitor type 1 (p = 0.98), and Von Willebrand factor antigen (p = 0.65) were not associated with delirium. CONCLUSIONS: In this study, MMP-9, protein C, and sTNFR1 were independently associated with subsequent ICU delirium. These results suggest that specific aspects of inflammation and coagulation may play a role in the evolution of delirium during critical illness and that these markers should be examined in larger studies of ICU patients.

Diurnal sedative changes during intensive care: impact on liberation from mechanical ventilation and delirium.

OBJECTIVE: To determine whether benzodiazepine and propofol doses are increased at night and whether daytime and nighttime sedative doses are associated with delirium, coma, and delayed liberation from mechanical ventilation. DESIGN: Single-center, prospective cohort study nested within the Awakening and Breathing Controlled randomized trial. SETTING: Saint Thomas Hospital in Nashville, TN, from 2004 to 2006. PATIENTS: Adult patients receiving mechanical ventilation for >12 hrs with continuous recording of hourly sedation dosing. INTERVENTIONS: We measured hourly doses of benzodiazepine and propofol exposure during the daytime (7 AM to 11 PM) and nighttime (11 PM to 7 AM) for 5 days. We quantified nighttime dose increases by subtracting the average hourly daytime dose on the preceding day from subsequent average hourly nighttime dose. We used multivariable logistic regression to determine whether daytime and nighttime dose increases were independently associated with delirium, coma, and delayed liberation from mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: Among 140 patients, the median Acute Physiology and Chronic Health Evaluation II score was 27 (interquartile range 22-33). Among those receiving the sedatives, benzodiazepine and propofol doses were increased at night on 40% and 41% of patient-days, respectively. Of 485 patient-days, delirium was present on 160 (33%) and coma on 206 (42%). In adjusted models, greater daytime benzodiazepine dose was independently associated with failed spontaneous breathing trial and extubation, and subsequent delirium (p<.02 for all). Nighttime increase in benzodiazepine dose was associated with failed spontaneous breathing trial (p<.01) and delirium (p=.05). Daytime propofol dose was marginally associated with subsequent delirium (p=.06). CONCLUSIONS: Nearly half of mechanically ventilated intensive care unit patients received greater doses of sedation at night, a practice associated with failed spontaneous breathing trials, coma, and delirium. Over the first 5 days in our study, patients spent 75% of their time in coma or delirium, outcomes that may be reduced by efforts to decrease sedative exposure during both daytime and nighttime hours in the intensive care unit.

Abnormal immune responses in persons with previous extrapulmonary tuberculosis in an in vitro model that simulates in vivo infection with Mycobacterium tuberculosis.

Persons with previous extrapulmonary tuberculosis have reduced peripheral blood mononuclear cell cytokine production and CD4(+) lymphocytes compared to persons with previous pulmonary tuberculosis or latent tuberculosis infection, but specific defects related to Mycobacterium tuberculosis infection of macrophages have not been characterized. The objective of this study was to further characterize the in vitro immune responses to M. tuberculosis infection in HIV-seronegative persons with previous extrapulmonary tuberculosis. Peripheral blood mononuclear cells were isolated from HIV-seronegative persons with previous extrapulmonary tuberculosis (n = 11), previous pulmonary tuberculosis (n = 21), latent M. tuberculosis infection (n = 19), and uninfected tuberculosis contacts (n = 20). Experimental conditions included M. tuberculosis-infected macrophages cultured with and without monocyte-depleted peripheral blood mononuclear cells. Concentrations of interleukin 1ß (IL-1ß), IL-4, IL-6, CXCL8 (IL-8), IL-10, IL-12p70, IL-17, CCL2 (monocyte chemoattractant protein 1), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ) were measured by multiplex cytokine array. When M. tuberculosis-infected macrophages were cocultured with monocyte-depleted peripheral blood mononuclear cells, IFN-γ (P = 0.01), TNF-α (P = 0.04), IL-10 (P < 0.001), and IL-6 (P = 0.03) exhibited similar continua of responses, with uninfected persons producing the lowest levels, followed by extrapulmonary tuberculosis cases, pulmonary tuberculosis controls, and persons with latent M. tuberculosis infection. A similar pattern was observed with CXCL8 (P = 0.04), IL-10 (P = 0.02), and CCL2 (P = 0.03) when monocyte-depleted peripheral blood mononuclear cells from the four groups were cultured alone. Persons with previous extrapulmonary tuberculosis had decreased production of several cytokines, both at rest and after stimulation with M. tuberculosis. Our results suggest that persons who develop extrapulmonary tuberculosis have a subtle global immune defect that affects their response to M. tuberculosis infection.

The association between brain volumes, delirium duration, and cognitive outcomes in intensive care unit survivors: the VISIONS cohort magnetic resonance imaging study*.

OBJECTIVE: Delirium duration is predictive of long-term cognitive impairment in intensive care unit survivors. Hypothesizing that a neuroanatomical basis may exist for the relationship between delirium and long-term cognitive impairment, we conducted this exploratory investigation of the associations between delirium duration, brain volumes, and long-term cognitive impairment. DESIGN, SETTING, AND PATIENTS: A prospective cohort of medical and surgical intensive care unit survivors with respiratory failure or shock. MEASUREMENTS: Quantitative high resolution 3-Tesla brain magnetic resonance imaging was used to calculate brain volumes at discharge and 3-month follow-up. Delirium was evaluated using the confusion assessment method for the intensive care unit; cognitive outcomes were tested at 3- and 12-month follow-up. Linear regression was used to examine associations between delirium duration and brain volumes, and between brain volumes and cognitive outcomes. RESULTS: A total of 47 patients completed the magnetic resonance imaging protocol. Patients with longer duration of delirium displayed greater brain atrophy as measured by a larger ventricle-to-brain ratio at hospital discharge (0.76, 95% confidence intervals [0.10, 1.41]; p = .03) and at 3-month follow-up (0.62 [0.02, 1.21], p = .05). Longer duration of delirium was associated with smaller superior frontal lobe (-2.11 cm(3) [-3.89, -0.32]; p = .03) and hippocampal volumes at discharge (-0.58 cm(3) [-0.85, -0.31], p < .001)--regions responsible for executive functioning and memory, respectively. Greater brain atrophy (higher ventricle-to-brain ratio) at 3 months was associated with worse cognitive performances at 12 months (lower Repeatable Battery for the Assessment of Neuropsychological Status score -11.17 [-21.12, -1.22], p = .04). Smaller superior frontal lobes, thalamus, and cerebellar volumes at 3 months were associated with worse executive functioning and visual attention at 12 months. CONCLUSIONS: These preliminary data show that longer duration of delirium is associated with smaller brain volumes up to 3 months after discharge, and that smaller brain volumes are associated with long-term cognitive impairment up to 12 months. We cannot, however, rule out that smaller preexisting brain volumes explain these findings.

The relationship between delirium duration, white matter integrity, and cognitive impairment in intensive care unit survivors as determined by diffusion tensor imaging: the VISIONS prospective cohort magnetic resonance imaging study*.

OBJECTIVE: Evidence is emerging that delirium duration is a predictor of long-term cognitive impairment in intensive care unit survivors. Relationships between 1) delirium duration and brain white matter integrity, and 2) white matter integrity and long-term cognitive impairment are poorly understood and could be explored using magnetic resonance imaging. DESIGN, SETTING, PATIENTS: A two-center, prospective cohort study incorporating delirium monitoring, neuroimaging, and cognitive testing in intensive care unit survivors. MEASUREMENTS: Delirium was evaluated with the Confusion Assessment Method for the Intensive Care Unit and cognitive outcomes were tested at 3 and 12-month follow-up. Following the intensive care unit stay, fractional anisotropy, a measure of white matter integrity, was calculated quantitatively using diffusion tensor imaging with a 3-T magnetic resonance imaging scanner at hospital discharge and 3-month follow-up. We examined associations between 1) delirium duration and fractional anisotropy and 2) fractional anisotropy and cognitive outcomes using linear regression adjusted for age and sepsis. RESULTS: A total of 47 patients with a median age of 50 yrs completed the diffusion tensor imaging-magnetic resonance imaging protocol. Greater duration of delirium (3 vs. 0 days) was associated with lower fractional anisotropy (i.e., reduced fractional anisotropy = white matter disruption) in the genu (-0.02; p = .04) and splenium (-0.01; p = .02) of the corpus callosum and anterior limb of the internal capsule (-0.02; p =.01) at hospital discharge. These associations persisted at 3 months for the genu (-0.02; p =.02) and splenium (-0.01; p = .004). Lower fractional anisotropy in the anterior limb of internal capsule at discharge and in genu of corpus callosum at three months was associated with worse cognitive scores at 3 and 12 months. CONCLUSIONS: In this pilot investigation, delirium duration in the intensive care unit was associated with white matter disruption at both discharge and 3 months. Similarly, white matter disruption was associated with worse cognitive scores up to 12 months later. This hypothesis-generating investigation may help design future studies to explore these complex relationships in greater depth.