The risk of delirium after sedation with propofol or midazolam in intensive care unit patients.

AIM: Knowledge of risk factors may provide strategies to reduce the high burden of delirium in intensive care unit (ICU) patients. We aimed to compare the risk of delirium after deep sedation with propofol versus midazolam in ICU patients. METHODS: In this prospective cohort study, ICU patients who were in an unarousable state for ≥24 h due to continuous sedation with propofol and/or midazolam were included. Patients admitted ≤24 h, those with an acute neurological disorder and those receiving palliative sedation were excluded. ICU patients were assessed daily for delirium during the 7 days following an unarousable state due to continuous sedation. RESULTS: Among 950 included patients, 605 (64%) subjects were delirious during the 7 days after awaking. The proportion of subsequent delirium was higher after midazolam sedation (152/207 [73%] patients) and after both propofol and midazolam sedation (257/377 [68%] patients), compared to propofol sedation only (196/366 [54%] patients). Midazolam sedation (adjusted cause-specific hazard ratio [adj. cause-specific HR] 1.32, 95% confidence interval [CI] 1.05-1.66) and propofol and midazolam sedation (adj. cause-specific HR 1.29, 95% CI 1.06-1.56) were associated with a higher risk of subsequent delirium compared to propofol sedation only. CONCLUSION: This study among sedated ICU patients suggests that, compared to propofol sedation, midazolam sedation is associated with a higher risk of subsequent delirium. This risk seems more apparent in patients with high cumulative midazolam intravenous doses. Our findings underpin the recommendations of the Society of Critical Care Medicine Pain, Agitation/sedation, Delirium, Immobility (rehabilitation/mobilization), and Sleep (disruption) guidelines to use propofol over benzodiazepines for sedation in ICU patients.

Relationship Between Pain and Delirium in Critically Ill Adults.

OBJECTIVES: Although opioids are frequently used to treat pain, and are an important risk for ICU delirium, the association between ICU pain itself and delirium remains unclear. We sought to evaluate the relationship between ICU pain and delirium. DESIGN: Prospective cohort study. SETTING: A 32-bed academic medical-surgical ICU. PATIENTS: Critically ill adults (n = 4,064) admitted greater than or equal to 24 hours without a condition hampering delirium assessment. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Daily mental status was classified as arousable without delirium, delirium, or unarousable. Pain was assessed six times daily in arousable patients using a 0-10 Numeric Rating Scale (NRS) or the Critical Care Pain Observation Tool (CPOT); daily peak pain score was categorized as no (NRS = 0/CPOT = 0), mild (NRS = 1-3/CPOT = 1-2), moderate (NRS = 4-6/CPOT = 3-4), or severe (NRS = 7-10/CPOT = 5-8) pain. To address missingness, a Multiple Imputation by Chained Equations approach that used available daily pain severity and 19 pain predictors was used to generate 25 complete datasets. Using a first-order Markov model with a multinomial logistic regression analysis, that controlled for 11 baseline/daily delirium risk factors and considered the competing risks of unarousability and ICU discharge/death, the association between peak daily pain and next-day delirium in each complete dataset was evaluated. RESULTS: Among 14,013 ICU days (contributed by 4,064 adults), delirium occurred on 2,749 (19.6%). After pain severity imputation on 1,818 ICU days, mild, moderate, and severe pain were detected on 2,712 (34.1%), 1,682 (21.1%), and 894 (11.2%) of the no-delirium days, respectively, and 992 (36.1%), 513 (18.6%), and 27 (10.1%) of delirium days (p = 0.01). The presence of any pain (mild, moderate, or severe) was not associated with a transition from awake without delirium to delirium (aOR 0.96; 95% CI, 0.76-1.21). This association was similar when days with only mild, moderate, or severe pain were considered. All results were stable after controlling for daily opioid dose. CONCLUSIONS: After controlling for multiple delirium risk factors, including daily opioid use, pain may not be a risk factor for delirium in the ICU. Future prospective research is required.

[Prevention of delirium in the Intensive Care Unit]. / Preventie van delier op de intensive care.

Delirium is highly prevalent in the Intensive Care Unit (ICU) and is strongly associated with negative patient outcomes. We aimed to present an overview of the effectiveness of non-pharmacological and pharmacological interventions to prevent delirium in ICU patients. Multicomponent non-pharmacological interventions are proven effective in the prevention of delirium. These interventions are aimed at multiple domains, including re-orientation, providing a safe and healing environment, cognitive stimulation, mobilization and family engagement. A special type of multicomponent intervention is the ''A-F bundle'', comprising both non-pharmacological and pharmacological interventions. Multicomponent non-pharmacological interventions and the ''A-F bundle'' are recommended. There is insufficient evidence for the effectiveness of pharmacological prophylaxis using antipsychotics, dexmedetomidine, melatonin or thiamin, except for delirium due to substance withdrawal. Therefore, pharmacological interventions should be aimed at minimizing delirogenousmedication (especially benzodiazepines and opiates), adequate pain management and the prevention of deep and continuous sedation.

Opioid Use Increases the Risk of Delirium in Critically Ill Adults Independently of Pain.

Rationale: It is unclear whether opioid use increases the risk of ICU delirium. Prior studies have not accounted for confounding, including daily severity of illness, pain, and competing events that may preclude delirium detection.Objectives: To evaluate the association between ICU opioid exposure, opioid dose, and delirium occurrence.Methods: In consecutive adults admitted for more than 24 hours to the ICU, daily mental status was classified as awake without delirium, delirium, or unarousable. A first-order Markov model with multinomial logistic regression analysis considered four possible next-day outcomes (i.e., awake without delirium, delirium, unarousable, and ICU discharge or death) and 11 delirium-related covariables (baseline: admission type, age, sex, Acute Physiology and Chronic Health Evaluation IV score, and Charlson comorbidity score; daily: ICU day, modified Sequential Organ Failure Assessment, ventilation use, benzodiazepine use, and severe pain). This model was used to quantify the association between opioid use, opioid dose, and delirium occurrence the next day.Measurements and Main Results: The 4,075 adults had 26,250 ICU days; an opioid was administered on 57.0% (n = 14,975), severe pain occurred on 7.0% (n = 1,829), and delirium occurred on 23.5% (n = 6,176). Severe pain was inversely associated with a transition to delirium (odds ratio [OR] 0.72; 95% confidence interval [CI], 0.53-0.97). Any opioid administration in awake patients without delirium was associated with an increased risk for delirium the next day [OR, 1.45; 95% CI, 1.24-1.69]. Each daily 10-mg intravenous morphine-equivalent dose was associated with a 2.4% increased risk for delirium the next day.Conclusions: The receipt of an opioid in the ICU increases the odds of transitioning to delirium in a dose-dependent fashion.

Haloperidol, clonidine and resolution of delirium in critically ill patients: a prospective cohort study.

PURPOSE: Haloperidol and clonidine are commonly used to treat agitation in delirious intensive care unit (ICU) patients, but it is unclear whether these agents may shorten the duration of delirium. The objective of this study was to determine whether haloperidol, clonidine, or their combined administration to delirious ICU patients results in delirium resolution. METHODS: This was a cohort study on a mixed ICU, excluding patients with a primary neurological disorder. The main outcome was the probability of delirium resolution, using propensity score matching and Markov multinomial logistic regression models for daily transitions. Secondary outcomes were delirium duration, number of delirium days, ventilation days, length of stay in the ICU and hospital, and ICU mortality. RESULTS: A total of 3614 patients were included (1165 delirious [32%]; 2449 non-delirious [68%]). Delirium occurred on 4708 (18.9%) of 24,906 days. The probability of delirium resolution was lower in delirious patients who received haloperidol (OR 0.47, 95% CI 0.39-0.57), clonidine (OR 0.78, 95% CI 0.63-0.97), or both (OR 0.45, 95% CI 0.36-0.56) compared to untreated delirious patients. Delirious patients who received haloperidol, clonidine, or both had generally longer delirium duration, more delirium and ventilation days, and spent more time in the ICU and in hospital than untreated delirious patients. These agents had no effect on ICU mortality. CONCLUSION: Haloperidol and clonidine use in delirious ICU patients may be associated with reduced probability of delirium resolution. This finding, however, merits further investigation given inherent limitations of this observational analysis.

Glucose variability during delirium in diabetic and non-diabetic intensive care unit patients: A prospective cohort study.

PURPOSE: To determine whether glucose variability is altered during delirium days compared to non-delirious days in critically ill patients with and without diabetes in the intensive care unit (ICU). MATERIALS AND METHODS: Critically ill patients with delirious and non-delirious days during ICU stay were included from a prospective cohort study which was conducted from January 2011- June 2013. Glucose variability was measured each observation day using various definitions (change in mean glucose, standard deviation, mean absolute glucose, daily delta and occurrence of hypo- and hyperglycemia). Mixed-effects models and generalized mixed-effects models with logit link function were performed to study the association between delirium and glucose variability, adjusting for potential confounders. RESULTS: With the exception of the risk of hypoglycemia, delirium was not linked to higher glucose variability using the various definitions of this estimate. For hypoglycemia, we did find an association with delirium in diabetic patients (OR adj.: 2.78; 95% CI: 1.71-6.32, p = 0.005), but not in non-diabetic patients (OR adj.: 1.16; 95% CI: 0.58-2.28, p = 0.689). CONCLUSIONS: Despite the positive association between delirium and hypoglycemia in critically ill patients with diabetes, delirium was not associated with more pronounced glucose variability. Our findings suggest that glucose levels should be monitored more closely in diabetic patients during delirium at the ICU to prevent hypoglycemia.

Long-Term Self-Reported Cognitive Problems After Delirium in the Intensive Care Unit and the Effect of Systemic Inflammation.

OBJECTIVES: To describe the association between intensive care unit (ICU) delirium and self-reported cognitive problems in 1-year ICU survivors, and investigate whether this association was altered by exposure to systemic inflammation during ICU stay. DESIGN: Prospective cohort study. SETTING: Dutch medical-surgical ICU. PARTICIPANTS: One-year ICU survivors, admitted to the ICU ≥48 hours. MEASUREMENTS: Self-reported cognitive problems were measured with the Cognitive Failures Questionnaire (CFQ). Cumulative exposure to systemic inflammation was based on all daily C-reactive protein (CRP) measurements during ICU stay, expressed as the area under the curve (AUC). Multivariable linear regression was conducted to evaluate the association between delirium and the CFQ. The effect of inflammation on the association between delirium and CFQ was assessed, comparing the effect estimate (B) of delirium and CFQ between models with and without inclusion of the AUC of CRP. RESULTS: Among 567 1-year ICU survivors, the CFQ was completed by 363 subjects. Subjects with multiple days of delirium during ICU stay reported more self-reported cognitive problems (Badj = 5.10, 95% CI 1.01-9.20), whereas a single day delirium was not associated with higher CFQ scores (Badj = -0.72, 95% CI -5.75 to 4.31). Including the AUC of CRP did not change the association between delirium and the CFQ (ratio for a single and multiple days were respectively: 1.00, 95%CI 0.59-1.44 and 0.86, 95% CI 0.47-1.16). CONCLUSION: Multiple days of delirium was associated with long-term self-reported cognitive problems. The cumulative exposure to systemic inflammation did not alter this association, suggesting that delirium in the context of little inflammation is also detrimental.

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.

Risk factors for delirium after on-pump cardiac surgery: a systematic review.

INTRODUCTION: As evidence-based effective treatment protocols for delirium after cardiac surgery are lacking, efforts should be made to identify risk factors for preventive interventions. Moreover, knowledge of these risk factors could increase validity of etiological studies in which adjustments need to be made for confounding variables. This review aims to systematically identify risk factors for delirium after cardiac surgery and to grade the evidence supporting these associations. METHOD: A prior registered systematic review was performed using EMBASE, CINAHL, MEDLINE and Cochrane from 1990 till January 2015 ( http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42014007371 ). All studies evaluating patients for delirium after cardiac surgery with cardiopulmonary bypass (CPB) using either randomization or multivariable data analyses were included. Data was extracted and quality was scored in duplicate. Heterogeneity impaired pooling of the data; instead a semi-quantitative approach was used in which the strength of the evidence was graded based on the number of investigations, the quality of studies, and the consistency of the association reported across studies. RESULTS: In total 1462 unique references were screened and 34 were included in this review, of which 16 (47 %) were graded as high quality. A strong level of evidence for an association with the occurrence of postoperative delirium was found for age, previous psychiatric conditions, cerebrovascular disease, pre-existent cognitive impairment, type of surgery, peri-operative blood product transfusion, administration of risperidone, postoperative atrial fibrillation and mechanical ventilation time. Postoperative oxygen saturation and renal insufficiency were supported by a moderate level of evidence, and there is no evidence that gender, education, CPB duration, pre-existent cardiac disease or heart failure are risk factors. CONCLUSION: Of many potential risk factors for delirium after cardiac surgery, for only 11 there is a strong or moderate level of evidence. These risk factors should be taken in consideration when designing future delirium prevention strategies trials or when controlling for confounding in future etiological studies.

Benzodiazepine-associated delirium in critically ill adults.

PURPOSE: The association between benzodiazepine use and delirium risk in the ICU remains unclear. Prior investigations have failed to account for disease severity prior to delirium onset, competing events that may preclude delirium detection, other important delirium risk factors, and an adequate number of patients receiving continuous midazolam. The aim of this study was to address these limitations and evaluate the association between benzodiazepine exposure and ICU delirium occurrence. METHODS: In a cohort of consecutive critically ill adults, daily mental status was classified as either awake without delirium, delirium, or coma. In a first-order Markov model, multinomial logistic regression analysis was used, which considered five possible outcomes the next day (i.e., awake without delirium, delirium, coma, ICU discharge, and death) and 16 delirium-related covariables, to quantify the association between benzodiazepine use and delirium occurrence the following day. RESULTS: Among 1112 patients, 9867 daily transitions occurred. Benzodiazepine administration in an awake patient without delirium was associated with increased risk of delirium the next day [OR 1.04 (per 5 mg of midazolam equivalent administered) 95 % CI 1.02-1.05). When the method of benzodiazepine administration was incorporated in the model, the odds of transitioning to delirium was higher with benzodiazepines given continuously (OR 1.04, 95 % CI 1.03-1.06) compared to benzodiazepines given intermittently (OR 0.97, 95 % CI 0.88-1.05). CONCLUSIONS: After addressing potential methodological limitations of prior studies, we confirm that benzodiazepine administration increases the risk for delirium in critically ill adults but this association seems to be limited to continuous infusion use only.

Anticholinergic Medication Use and Transition to Delirium in Critically Ill Patients: A Prospective Cohort Study.

OBJECTIVE: Although cholinergic deficiency is presumed to increase delirium risk and use of medication with anticholinergic properties in the ICU is frequent, the relationship between anticholinergic medication use and delirium in this setting remains unclear. We investigated whether exposure to medication with anticholinergic properties increases the probability of transitioning to delirium in critically ill adults and whether this relationship is affected by age or the presence of acute systemic inflammation. DESIGN: Prospective cohort study. SETTING: A 32-bed medical-surgical ICU at an academic medical center. PATIENTS: Critically ill adults admitted to the ICU for more than 24 hours without an acute neurological disorder or another condition that would hamper delirium assessment. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Daily anticholinergic burden was calculated for each patient based on the sum of the Anticholinergic Drug Scale score for each medication administered. Daily mental status was classified as "coma," "delirium," or an "awake without delirium" state. The primary outcome, the daily transition from an "awake without delirium" state to "delirium," was analyzed using a first-order Markov model that adjusted for eight covariables. A total of 1,112 patients were evaluated over 9,867 ICU days. The daily median summed Anticholinergic Drug Scale score was 2 (interquartile range, 1-3). The transition from being in an "awake without delirium" state to "delirium" occurred on 562 of ICU days (6%). After correcting for confounding, a one-unit increase in the Anticholinergic Drug Scale score resulted in a nonsignificant increase in the probability of delirium occurring the next day (odds ratio, 1.05; 95% CI, 0.99-1.10). Neither age nor the presence of acute systemic inflammation modified this relationship. CONCLUSIONS: Exposure to medication with anticholinergic properties, as defined by the Anticholinergic Drug Scale, does not increase the probability of delirium onset in patients who are awake and not delirious in the ICU.

Delirium detection using EEG: what and how to measure.

BACKGROUND: Despite its frequency and impact, delirium is poorly recognized in postoperative and critically ill patients. EEG is highly sensitive to delirium but, as currently used, it is not diagnostic. To develop an EEG-based tool for delirium detection with a limited number of electrodes, we determined the optimal electrode derivation and EEG characteristic to discriminate delirium from nondelirium. METHODS: Standard EEGs were recorded in 28 patients with delirium and 28 age- and sex-matched patients who had undergone cardiothoracic surgery and were not delirious, as classified by experts using Diagnostic and Statistical Manual of Mental Disorders, 4th edition, criteria. The first minute of artifact-free EEG data with eyes closed as well as with eyes open was selected. For each derivation, six EEG parameters were evaluated. Using Mann-Whitney U tests, all combinations of derivations and parameters were compared between patients with delirium and those without. Corresponding P values, corrected for multiple testing, were ranked. RESULTS: The largest difference between patients with and without delirium and highest area under the receiver operating curve (0.99; 95% CI, 0.97-1.00) was found during the eyes-closed periods of the EEG, using electrode derivation F8-Pz (frontal-parietal) and relative δ power (median [interquartile range (IQR)] for delirium, 0.59 [IQR, 0.47-0.71] and for nondelirium, 0.20 [IQR, 0.17-0.26]; P = .0000000000018). With a cutoff value of 0.37, it resulted in a sensitivity of 100% (95% CI, 100%-100%) and specificity of 96% (95% CI, 88%-100%). CONCLUSIONS: In a homogenous population of nonsedated patients who had undergone cardiothoracic surgery, we observed that relative δ power from an eyes-closed EEG recording with only two electrodes in a frontal-parietal derivation can distinguish among patients who have delirium and those who do not.

A systematic review of risk factors for delirium in the ICU.

OBJECTIVE: Although numerous risk factors for delirium in the ICU have been proposed, the strength of evidence supporting each risk factor remains unclear. This study systematically identifies risk factors for delirium in critically ill adults where current evidence is strongest. DATA SOURCES: CINAHL, EMBASE, MEDLINE, the Cochrane Central Register for Controlled Trials, and the Cochrane Database of Systematic Reviews. STUDY SELECTION: Studies published from 2000 to February 2013 that evaluated critically ill adults, not undergoing cardiac surgery, for delirium, and used either multivariable analysis or randomization to evaluate variables as potential risk factors for delirium. DATA EXTRACTION: Data were abstracted in duplicate, and quality was scored using Scottish Intercollegiate Guidelines Network checklists (i.e., high, acceptable, and low). Using a best-evidence synthesis each variable was evaluated using 3 criteria: the number of studies investigating it, the quality of these studies, and whether the direction of association was consistent across the studies. Strengths of association were not summarized. Strength of evidence was defined as strong (consistent findings in ≥2 high quality studies), moderate (consistent findings in 1 high quality study and ≥1 acceptable quality studies), inconclusive (inconsistent findings or 1 high quality study or consistent findings in only acceptable quality/low quality studies) or no evidence available. DATA SYNTHESIS: Among 33 studies included, 70% were high quality. There was strong evidence that age, dementia, hypertension, pre-ICU emergency surgery or trauma, Acute Physiology and Chronic Health Evaluation II score, mechanical ventilation, metabolic acidosis, delirium on the prior day, and coma are risk factors for delirium, that gender is not associated with delirium, and that use of dexmedetomidine is associated with a lower delirium prevalence. There is moderate evidence that multiple organ failure is a risk factor for delirium. CONCLUSIONS: Only 11 putative risk factors for delirium are supported by either strong or moderate level of evidence. These factors should be considered when designing delirium prevention strategies or controlling for confounding in future etiologic studies.

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.

The attributable mortality of delirium in critically ill patients: prospective cohort study.

OBJECTIVE: To determine the attributable mortality caused by delirium in critically ill patients. DESIGN: Prospective cohort study. SETTING: 32 mixed bed intensive care unit in the Netherlands, January 2011 to July 2013. PARTICIPANTS: 1112 consecutive adults admitted to an intensive care unit for a minimum of 24 hours. EXPOSURES: Trained observers evaluated delirium daily using a validated protocol. Logistic regression and competing risks survival analyses were used to adjust for baseline variables and a marginal structural model analysis to adjust for confounding by evolution of disease severity before the onset of delirium. MAIN OUTCOME MEASURE: Mortality during admission to an intensive care unit. RESULTS: Among 1112 evaluated patients, 558 (50.2%) developed at least one episode of delirium, with a median duration of 3 days (interquartile range 2-7 days). Crude mortality was 94/558 (17%) in patients with delirium compared with 40/554 (7%) in patients without delirium (P<0.001). Delirium was significantly associated with mortality in the multivariable logistic regression analysis (odds ratio 1.77, 95% confidence interval 1.15 to 2.72) and survival analysis (subdistribution hazard ratio 2.08, 95% confidence interval 1.40 to 3.09). However, the association disappeared after adjustment for time varying confounders in the marginal structural model (subdistribution hazard ratio 1.19, 95% confidence interval 0.75 to 1.89). Using this approach, only 7.2% (95% confidence interval -7.5% to 19.5%) of deaths in the intensive care unit were attributable to delirium, with an absolute mortality excess in patients with delirium of 0.9% (95% confidence interval -0.9% to 2.3%) by day 30. In post hoc analyses, however, delirium that persisted for two days or more remained associated with a 2.0% (95% confidence interval 1.2% to 2.8%) absolute mortality increase. Furthermore, competing risk analysis showed that delirium of any duration was associated with a significantly reduced rate of discharge from the intensive care unit (cause specific hazard ratio 0.65, 95% confidence interval 0.55 to 0.76). CONCLUSIONS: Overall, delirium prolongs admission in the intensive care unit but does not cause death in critically ill patients. Future studies should focus on episodes of persistent delirium and its long term sequelae rather than on acute mortality.Trial registration Clinicaltrials.gov NCT01905033.