Inflammation biomarkers and delirium in critically ill patients

Temporal biomarker profiles and their association with ICU acquired delirium: a cohort study

BACKGROUND

Neuroinflammation is thought to play an important role in the pathogenesis of ICU-acquired delirium, but the association between inflammatory and brain-specific proteins and ICU delirium is poor. We investigated whether or not serial determinations of markers may improve this association.

METHODS

Critically ill patients with a high risk of ICU delirium and with an ICU length of stay of at least 6 days were included in the study. Blood was drawn on days 1, 2, 4 and 6 after ICU admission and analyzed for different markers of inflammation and several brain proteins. Differences in courses over time prior to and following the onset of delirium and absolute differences over time were analyzed in patients with and without delirium using repeated measurement analysis of variance. In addition, a cross-sectional analysis of levels of these markers before the first onset of delirium was performed.

RESULTS

Fifty patients were included in this study. In the longitudinal analysis, there were no differences in the levels of any of the markers immediately prior to and following the onset of delirium, but overall, median levels of adiponectin (9019 (IQR 5776-15,442) vs. 6148 (IQR 4447-8742) ng/ml, p = 0.05) were significantly higher in patients with delirium compared to patients without delirium. In the cross-sectional analysis, median levels of the brain protein Tau (90 (IQR 46-224) vs. 31 (IQR 31-52) pg/ml, p = 0.009) and the ratio Tau/amyloid β_1-42 (1.42 ((IQR 0.9-2.57) vs. 0.68 (IQR 0.54-0.96), p = 0.003) were significantly higher in patients with hypoactive delirium compared to patients without. Levels of neopterin (111 (IQR 37-111) vs. 29 (IQR 16-64) mmol/l, p = 0.004) and IL-10 (28 (IQR 12-39) vs. 9 (IQR 4-12) pg/ml, p = 0.001) were significantly higher in patients with hypoactive delirium compared to patients with mixed-type delirium.

CONCLUSIONS

While there are differences in markers (adiponectin and several brain proteins) between patients with and without delirium, the development of delirium is not preceded by a change in the biomarker profile of inflammatory markers or brain proteins. Patients with hypoactive delirium account for the observed differences in biomarkers.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT 01274819 . Registered on 12 January 2011.

Reduced ex vivo release of pro-inflammatory cytokines and elevated plasma interleukin-6 are inflammatory signatures of post-stroke delirium

Background

Experimental studies suggest that systemic inflammation contributes to the pathophysiology of delirium. The aim of our study was to determine blood-derived inflammatory signatures of post-stroke delirium.

Methods

We included 144 ischemic stroke patients. We assessed delirium on a daily basis during the first 7 days of hospitalization. Venous blood was collected at day 3 after the onset of stroke and stimulated ex vivo with lipopolysaccharide (LPS). We measured LPS-induced cytokine concentration (TNFα, IP-10, IL-1β, IL-6, IL-8, IL-10, and IL-12p70) as well as plasma levels of IL-6 and TNFα.

Results

Delirium was diagnosed in 21.5% of patients. After correction for monocyte count, patients with delirium had reduced LPS-induced TNFα, IP-10, IL-1β, IL-6, and IL-12 release. The plasma IL-6 level was higher in delirious patients compared to patients without delirium. After adjusting for stroke severity and infections, higher ex vivo TNFα (OR 0.29, 95%CI 0.11–0.72, P = 0.01), IP-10 (OR 0.25, 95%CI 0.08–0.73, P = 0.01), IL-1β (OR 0.42, 95%CI 0.20–0.89, P = 0.02), and IL-12 (OR 0.07, 95%CI 0.01–0.70, P = 0.02) release was associated with the reduced risk of delirium. In multivariate analysis, the higher plasma IL-6 was associated with the increased risk of delirium (OR 1.61, 95%CI 1.00–2.58, P = 0.04).

Conclusions

Reduced ex vivo release of pro-inflammatory cytokines after LPS stimulation and the elevated plasma IL-6 are signatures of post-stroke delirium.

The confused oncologic patient: a rational clinical approach

PURPOSE OF REVIEW

The purpose of this review is to provide a practical clinical approach to confusion in the patient with cancer. Confusion in the cancer population has a broader differential diagnosis than in the general medical population. The clinician must consider the usual differential diagnoses as well as causes unique to the cancer patient including direct complications from the cancer and indirect complications related to cancer treatment.

RECENT FINDINGS

In the recent age of precision medicine, the oncologist now utilizes the genomic profile of both the patient and the tumor to provide advanced biologic therapies including targeted anticancer drugs, antiangiogenic agents, and immunotherapy. Such advances carry with them an emerging pattern of neurotoxicity which, although less well described in the literature, is now an important consideration to the clinical approach to confusion in cancer patients.

SUMMARY

Confusion is the most common neurologic complication in cancer and is associated with significant morbidity, mortality, and prolonged hospital stays resulting in increased healthcare costs. Early recognition and treatment of delirium is essential to improve clinical outcomes.

Hypertonic saline for prevention of delirium in geriatric patients who underwent hip surgery

BACKGROUND

Postoperative delirium (POD) is a common disorder in the elderly patients, and neuroinflammation is the possible underlying mechanism. This study is designed to determine whether or not hypertonic saline (HS) pre-injection can alleviate POD in aged patients.

METHODS

This prospective study recruited 120 geriatric patients who underwent hip surgery. The patients were randomly divided into two groups: control group (NS group) and HS group. Patients in the NS group were pre-injected with 4 mL/kg isotonic saline, and those in the HS group were pre-injected with 4 mL/kg 7.5% HS. All 120 patients were then subjected to general anesthesia. Blood samples were extracted to detect the concentration of inflammatory factors, namely, IL-1β, IL-6, IL-10, and TNF-α, and the nerve injury factor S100β. Flow cytometry was used to detect the number of monocytes in peripheral venous blood and evaluate the relationship of inflammation to delirium. The nursing delirium screening scale (Nu-DESC) was used to determine cognitive function 1 to 3 days postoperatively.

RESULTS

Analysis using random-effect multivariable logistic regression indicated that HS administration before anesthesia was associated with a low risk of POD (odds ratio [OR], 0.13; 95% CI, 0.04 to 0.41; P = 0.001) and few CD14 + CD16+ monocytes (β = - 0.61; 95% CI, - 0.74 to - 0.48; P = 0.000) the following day. When the association between HS and delirium was controlled for CD14 + CD16+ monocytes, the effect size became nonsignificant (odds ratio [OR], 0.86; 95% CI, 0.14 to 5.33; P = 0.874). TNF-α was significantly associated with POD (odds ratio [OR], 1.10; 95% CI, 1.05 to 1.16; P = 0.000). However, IL-1β, IL-6, IL-10, and S100β were not significantly related to POD.

CONCLUSION

HS can alleviate POD in geriatric patients and may inhibit the secretion of inflammatory factors by monocytes.

Evaluation of early administration of simvastatin in the prevention and treatment of delirium in critically ill patients undergoing mechanical ventilation (MoDUS): a randomised, double-blind, placebo-controlled trial

BACKGROUND

Delirium in critically ill patients is associated with poor clinical outcomes. Neuroinflammation might be an important mechanism in the pathogenesis of delirium, and since simvastatin has anti-inflammatory properties it might reduce delirium. We aimed to establish whether early treatment with simvastatin would decrease the time that survivors of critical illness spent in delirium or coma.

METHODS

We undertook this randomised, double-blind, placebo-controlled trial in a general adult intensive care unit (ICU) in Watford General Hospital (Watford, UK). We enrolled critically ill patients (≥18 years) needing mechanical ventilation within 72 h of admission. We randomly assigned patients (1:1 ratio) to receive either simvastatin 80 mg or placebo daily for up to a maximum of 28 days, irrespective of coma or delirium status. We assessed delirium using the Confusion Assessment Method for the ICU (CAM-ICU). The primary outcome was number of days alive and was assessed as delirium-free and coma-free in the first 14 days after being randomly allocated to receive treatment or placebo. ICU clinical and research staff and patients were masked to treatment. We did intention-to-treat analyses with no extrapolation. This trial is registered with the International Standard Randomised Controlled Trial Registry, number ISRCTN89079989.

FINDINGS

Between Feb 1, 2013, and July 29, 2016, 142 patients were randomly assigned to receive simvastatin (n=71) or placebo (n=71), and were included in the final analysis. The mean number of days alive without delirium and without coma at day 14 did not differ significantly between the two groups (5·7 days [SD 5·1] with simvastatin and 6·1 days [5·2] with placebo; mean difference 0·4 days, 95% CI -1·3 to 2·1; p=0·66). The most common adverse event was an elevated creatine kinase concentration to more than ten times the upper limit of normal (eight [11%] in the simvastatin group vs three [4%] in the placebo group p=0·208). No patient had a serious adverse event related to the study drug.

INTERPRETATION

These results do not support the hypothesis that simvastatin modifies duration of delirium and coma in critically ill patients.

FUNDING

National Institute for Health Research.

Higher C-Reactive Protein Levels Predict Postoperative Delirium in Older Patients Undergoing Major Elective Surgery: A Longitudinal Nested Case-Control Study

BACKGROUND

Delirium is a common, morbid, and costly postoperative complication. We aimed to identify blood-based postoperative delirium markers in a nested case-control study of older surgical patients using a proteomics approach followed by enzyme-linked immunosorbent assay (ELISA) validation.

METHODS

The Successful Aging after Elective Surgery study enrolled dementia-free adults ≥70 years old undergoing major scheduled noncardiac surgery (N = 566; 24% delirium). Plasma was collected at four time points: preoperative, postanesthesia care unit, postoperative day 2, and 1 month postoperative. Matched pairs were selected for the independent discovery (39 pairs) and replication cohorts (36 pairs), which were subsequently combined into the pooled cohort (75 pairs). Isobaric tags for relative and absolute quantitation-based relative quantitation mass spectrometry proteomics were performed to identify the strongest delirium-related protein, which was selected for ELISA validation. Using the ELISA results, statistical analyses using nonparametric signed rank tests were performed in all cohorts examining the association between the identified protein and delirium.

RESULTS

C-reactive protein emerged from the proteomics analysis as the strongest delirium-related protein. Validation by ELISA confirmed that compared with controls, cases had significantly higher C-reactive protein levels in the discovery, replication, and pooled cohorts at the preoperative (median paired difference [MPD] 1.97 mg/L [p < .05], 0.29 mg/L, 1.56 mg/L [p < .01]), postanesthesia care unit (MPD 2.83 mg/L, 2.22 mg/L [p < .05], 2.53 mg/L [p < .01]) and postoperative day 2 (MPD 71.97 mg/L [p < .01], 35.18 mg/L [p < .05], 63.76 mg/L [p < .01]) time points, but not 1 month postoperative (MPD 2.72 mg/L, -0.66 mg/L, 1.10 mg/L).

CONCLUSIONS

Elevated preoperative and postoperative plasma levels of C-reactive protein were associated with delirium, suggesting that a preinflammatory state and heightened inflammatory response to surgery are potential pathophysiologic mechanisms of delirium.

Systemic TNF-α produces acute cognitive dysfunction and exaggerated sickness behavior when superimposed upon progressive neurodegeneration

Inflammation influences chronic neurodegeneration but its precise roles are not yet clear. Systemic inflammation caused by infection, trauma or co-morbidity can alter the brain's inflammatory status, produce acute cognitive impairments, such as delirium, and drive new pathology and accelerated decline. Consistent with this, elevated systemic TNF-α is associated with more rapid cognitive decline over 6months in Alzheimer's disease patients. In the current study we challenged normal animals and those with existing progressive neurodegeneration (ME7 prion disease) with TNF-α (i.p.) to test the hypothesis that this cytokine has differential effects on cognitive function, sickness behavior and features of underlying pathology contingent on the animals' baseline condition. TNF-α (50μg/kg) had no impact on performance of normal animals (normal brain homogenate; NBH) on working memory (T-maze) but produced acute impairments in ME7 animals similarly challenged. Plasma TNF-α and CCL2 levels were equivalent in NBH and ME7 TNF-challenged animals but hippocampal and hypothalamic transcription of IL-1β, TNF-α and CCL2 and translation of IL-1β were higher in ME7+TNF-α than NBH+TNF-α animals. TNF-α produced an exaggerated sickness behavior response (hypothermia, weight loss, inactivity) in ME7 animals compared to that in NBH animals. However a single challenge with this dose was not sufficient to produce de novo neuronal death, synaptic loss or tau hyperphosphorylation that was distinguishable from that arising from ME7 alone. The data indicate that acutely elevated TNF-α has robust acute effects on brain function, selectively in the degenerating brain, but more sustained levels may be required to significantly impact on underlying neurodegeneration.

Characterization of Brain-Heart Interactions in a Rodent Model of Sepsis

Loss of heart rate variability (HRV) and autonomic dysfunction are associated with poor outcomes in critically ill patients. Neuronal networks comprising brainstem and hypothalamus are involved in the “flight-or-fight” response via control over the autonomic nervous system and circulation. We hypothesized that sepsis-induced inflammation in brain regions responsible for autonomic control is associated with sympathovagal imbalance and depressed contractility. Sepsis was induced by fecal slurry injection in fluid-resuscitated rats. Sham-operated animals served as controls. Echocardiography-derived peak velocity (PV) was used to separate septic animals into good (PV ≥0.93 m/s, low 72-h mortality) and bad (PV <0.93, high 72-h mortality) prognosis. Cytokine protein levels were assessed by ELISA. All experiments were performed at 24 h post-insult. Increased levels of inflammation and oxidative injury were observed in the hypothalamus (TNF-α, IL-10, nitrite and nitrate and carbonyl groups) and brainstem (IL-1, IL-6, IL-10, nitrite and nitrate and carbonyl groups) of the septic animals (p < 0.05 vs. sham), but not in the pre-frontal cortex, an area not directly implicated in control of the autonomic nervous system. Good prognosis septic animals had increased sympathetic output and increased left ventricular contractility (p < 0.05 vs. sham). There was a significant inverse correlation between high frequency power (a marker of parasympathetic outflow) and contractility (r = −0.73, p < 0.05). We found no correlation between the degree of inflammation or injury to autonomic centers and cardiovascular function. In conclusion, control of autonomic centers and cardiac function in our long-term rodent model of sepsis was related to clinical severity but not directly to the degree of inflammation.

A clinical perspective of sepsis-associated delirium

The term sepsis-associated encephalopathy (SAE) has been applied to animal models, postmortem studies in patients, and severe cases of sepsis. SAE is considered to include all types of brain dysfunction, including delirium, coma, seizure, and focal neurological signs. Clinical data for sepsis-associated delirium (SAD) have been accumulating since the establishment of definitions of coma or delirium and the introduction of validated screening tools. Some preliminary studies have examined the etiology of SAD. Neuroinflammation, abnormal cerebral perfusion, and neurotransmitter imbalances are the main mechanisms underlying the development of SAD. However, there are still no specific diagnostic blood, electrophysiological, or imaging tests or treatments specific for SAD. The duration of delirium in intensive care patients is associated with long-term functional disability and cognitive impairment, although this syndrome usually reverses after the successful treatment of sepsis. Once the respiratory and hemodynamic states are stabilized, patients with severe sepsis or septic shock should receive rehabilitation as soon as possible because early initiation of rehabilitation can reduce the duration of delirium. We expect to see further pathophysiological data and the development of novel treatments for SAD now that reliable and consistent definitions of SAD have been established.

Haloperidol Suppresses NF-kappaB to Inhibit Lipopolysaccharide-Induced Pro-Inflammatory Response in RAW 264 Cells

Background

Haloperidol, a tranquilizing agent, is administered both to treat symptoms of psychotic disorders and to sedate agitated and delirious patients. Notably, haloperidol has been suggested to inhibit the immune response through unknown mechanisms. We hypothesized that the sedative modulates the immune response via NF-κB.

Material/Methods

Using flow cytometry, we analyzed the effects of haloperidol on expression CD80 and CD86 in RAW 264 cells and in primary macrophages derived from bone marrow. Secretion of interleukin (IL)-1β, IL-6, and IL-12 p40 was measured by enzyme-linked immunosorbent assay. In addition, NF-κB activation was evaluated using a reporter assay based on secretory embryonic alkaline phosphatase. Finally, synthetic antagonists were used to identify the dopamine receptor that mediates the effects of haloperidol.

Results

Haloperidol inhibited NF-κB activation, and thereby suppressed expression of CD80, as well as secretion of IL-1β, IL-6, and IL-12 p40. CD80 and IL-6 levels were similarly attenuated by a D2-like receptor antagonist, but not by a D1-like receptor antagonist.

Conclusions

The data strongly suggest that haloperidol inhibits the immune response by suppressing NF-κB signaling via the dopamine D2 receptor.

Soluble tumor necrosis factor receptors as predictors of 1-year mortality and renal dysfunction after liver transplantation

BACKGROUND

Several risk factors influence survival after liver transplantation (LT). Some research has demonstrated a relationship between soluble tumor necrosis factor receptors (sTNFRs) and worse clinical liver disease outcomes, but there are no data showing an association between sTNFRs and outcomes after LT. The primary aim of this study was to determine whether an association exists between perioperative sTNFRs and renal dysfunction or mortality after LT.

METHODS

Data were collected prospectively from 122 patients submitted to deceased-donor orthotopic LT. Blood samples were collected at seven different perioperative times and analyzed by ELISA. The statistical analysis included univariate analysis followed by logistic regression. The predictive value of significant variables was assessed using ROC curves.

RESULTS

One-month and 1-year LT survivals were 91% and 81%, respectively. Increased levels of soluble tumor necrosis factor receptor 1 (sTNF-R1) after 24h of graft perfusion were associated with postoperative Renal Replacement Therapy (RRT) (OR 1.25) and 1-year mortality (OR 1.1). RRT was associated with 30-day and 1-year LT mortality, with OR 19.78 and 45.45, respectively.

CONCLUSION

A higher sTNF-R1 level measured 24h after graft perfusion is an independent predictor of RRT and 1-year mortality after LT.

Incidence and risk factors of delirium in multi-center Thai surgical intensive care units: a prospective cohort study

Background

Delirium in intensive care units increases morbidity and mortality risk. The incidence and risk factors of delirium vary among studies. This study therefore aimed to determine the incidence and risk factors of delirium in Thai university-based surgical intensive care units.

Methods

A multi-center, prospective cohort study was conducted. All patients who had been admitted to surgical intensive care units (SICU) between April 2011 and January 2012 were enrolled. Delirium was diagnosed using the Intensive Care Delirium Screening Checklists (ICDSC). The univariable and multivariable risk regression analyses were analyzed and presented as risk ratio (RR) and 95 % confidence interval (CI).

Results

The overall incidence of delirium was 3.6 % (162 of 4450, 95 % CI 3.09–4.19 %) whilst the incidences of delirium for patients being admitted ≤48 and >48 h were 0.7 % (21 of 2967, 95 % CI 0.41–1.01 %) and 8.3 % (141 of 1685, 95 % CI 7.04–9.68 %), respectively. The incidence of delirium on each study site was significantly different (range between 0 and 13.9 %, P < 0.001). Delirious patients had a significantly higher age (65.3 ± 15.6 versus 61.8 ± 17.3 years, P = 0.013), higher Acute Physiology and Chronic Health Evaluation II score (APACHE II score) (16 (12–23) versus 10 (7–15), P < 0.001), and higher sequential organ failure assessment score (5 (2–8) versus 2 (1–5), P < 0.001). The median duration of delirium was 3 (1–5) days. Delirious patients had significantly longer duration of ICU stay (8 (5–19) versus 2 (1–4), P < 0.001) and higher ICU mortality rate (23.5 versus 8.1 %, P < 0.001). Sepsis (RR = 3.70, 95 % CI 2.33–5.90, P < 0.001), exposure to sedative medications (RR = 3.54, 95 % CI 2.13–5.87, P < 0.001), higher APACHE II score (RR = 2.79, 95 % CI 1.98–3.95, P < 0.001), thoracic surgery (RR = 1.74, 95 % CI 1.09–2.78, P = 0.021), and emergency surgery (RR = 1.70, 95 % CI 1.09–2.65, P = 0.019) were independent risk factors of delirium in SICU.

Conclusions

Sepsis, exposure to sedative medications, higher APACHE II score, thoracic surgery, and emergency surgery were independent risk factors of delirium in Thai university-based surgical intensive care units.

Effect of therapeutic plasma exchange on plasma levels and total removal of adipokines and inflammatory markers

Background

Aside from well-established inflammatory mediators adipokines have recently been found to play an important role in a variety of immunologic diseases. Therapeutic plasma exchange (TPE) is an established treatment modality for the acute removal of pathophysiological relevant disease mediators. The aim of this study was to determine adipokine removal during TPE therapy.

Methods

21 Caucasian patients (10 females, 11 males) with an indication for TPE using albumin as exchange fluid received two consecutive TPE sessions. Blood samples for measurement of resistin, leptin, sICAM-1, sCD40L, MCP-1, and sTNF-R were drawn before and at the end of each TPE session. Samples from the total removed plasma were collected at the end of every treatment.

Results

We found a significant reduction in pre- vs. post-TPE plasma concentrations for sICAM-1 (517 ± 246 vs. 260 ± 159 ng/ml, p < 0.0001), sTNF-R (8.1 ± 6.4 vs. 5.7 ± 3.9 ng/ml, p < 0.05), and resistin plasma levels (14.3 ± 6.9 vs. 9.5 ± 4.7 ng/ml, p < 0.001). Solely sICAM-1 reduction persisted for 25 ± 5 h between the first and second TPE treatment, while the other investigated mediators increased to baseline levels. Substantial amounts of all measured mediators could be recovered from the removed plasma.

Conclusions

TPE provides a persistent reduction in sICAM-1 levels and temporarily affects several adipokine and cytokine plasma levels. Our findings are of importance not only for the interpretation of blood levels of cytokines in patients undergoing TPE but provide solid evidence that TPE markedly decreases sICAM-1.

Fluid accumulation threshold measured by acute body weight change after admission in general surgical intensive care units: how much should be concerning?

Background

The objective of this study (ClinicalTrials.gov: NCT01351506) was to identify the threshold level of fluid accumulation measured by acute body weight (BW) change during the first week in a general surgical intensive care unit (ICU), which is associated with ICU mortality and other adverse outcomes.

Methods

Four hundred sixty-five patients were prospectively followed for a 28-day period. The maximum BW change threshold during the first week was evaluated by the maximum percentage change in BW from the ICU admission weight (Max%ΔBW). Daily screening of adverse events in the ICU were recorded. The cutoff point of Max%ΔBW on ICU mortality was defined by considering the area under the receiver operating characteristic (ROC) curve, intersection of the sensitivity and specificity, and the Youden Index. Univariable and multivariable regression analyses were used to demonstrate the associations. Statistical significance was defined as P<0.05.

Results

The appropriate cutoff value of Max%ΔBW threshold was 5%. Regarding the multivariable regression model, in overall patients, the occurrence of the following adverse events (expressed as adjusted odds ratio [95% confidence interval]) were significantly associated with a Max%ΔBW of >5%: ICU mortality (2.38 [1.25–4.54]) (P=0.008), ICU mortality in patients without renal replacement therapy (RRT) (2.47 [1.21–5.06]) (P=0.013), reintubation within 72 hours (2.51 [1.04–6.00]) (P=0.039), RRT requirement (2.67 [1.13–6.33]) (P=0.026), and delirium (1.97 [1.08–3.57]) (P=0.025). Regarding the postoperative subgroup, a Max%ΔBW value of more than 5% was significantly associated with: ICU mortality (3.87 [1.38–10.85]) (P=0.010), ICU mortality in patients without RRT (6.32 [1.85–21.64]) (P=0.003), reintubation within 72 hours (4.44 [1.30–15.16]) (P=0.017), and vasopressor requirement (2.04 [1.04–4.01]) (P=0.037).

Conclusion

Fluid accumulation, measured as acute BW change of more than the threshold of 5% during the first week of ICU admission, is associated with adverse outcomes of higher ICU mortality, especially in the patients without RRT, with reintubation within 72 hours, with RRT requirement, with vasopressor requirement, and with delirium. Some of these effects were higher in postoperative patients. This threshold value might be an indicator for caution during fluid management in surgical ICU.

The association between acute respiratory distress syndrome, delirium, and in-hospital mortality in intensive care unit patients

RATIONALE

Both acute respiratory distress syndrome (ARDS) and intensive care unit (ICU) delirium are associated with significant morbidity and mortality. However, the risk of delirium and its impact on mortality in ARDS patients is unknown.

OBJECTIVES

To determine if ARDS is associated with a higher risk for delirium compared with respiratory failure without ARDS, and to determine the association between ARDS and in-hospital mortality after adjusting for delirium.

METHODS

Prospective observational cohort study of adult ICU patients admitted to two urban academic hospitals.

MEASUREMENTS AND MAIN RESULTS

Delirium was assessed daily using the Confusion Assessment Method for the ICU and Richmond Agitation and Sedation Scale. Of the 564 patients in our cohort, 48 had ARDS (9%). Intubated patients with ARDS had the highest prevalence of delirium compared with intubated patients without ARDS and nonintubated patients (73% vs. 52% vs. 21%, respectively; P < 0.001). After adjusting for common risk factors for delirium, ARDS was associated with a higher risk for delirium compared with mechanical ventilation without ARDS (odds ratio [OR], 6.55 [1.56-27.54]; P = 0.01 vs. OR, 1.98 [1.16-3.40]; P < 0.013); reference was nonintubated patients. Although ARDS was significantly associated with hospital mortality (OR, 10.44 [3.16-34.50]), the effect was largely reduced after adjusting for delirium and persistent coma (OR, 5.63 [1.55-20.45]).

CONCLUSIONS

Our findings suggest that ARDS is associated with a greater risk for ICU delirium than mechanical ventilation alone, and that the association between ARDS and in-hospital mortality is weakened after adjusting for delirium and coma. Future studies are needed to determine if prevention and reduction of delirium in ARDS patients can improve outcomes.

Inflammation biomarkers and delirium in critically ill patients: new insights?

The pathophysiological mechanism of the serious and frequently occurring disorder delirium is poorly understood. Inflammation and sepsis are known risk factors for ICU delirium and therefore these patients are highly susceptible to delirium. Several studies have been performed to determine which cytokines are most associated with delirium but the results are inconclusive. Also, new biomarkers associated with brain dysfunction and cognitive impairment are still recognized and need to be studied to determine their relation with delirium. In this commentary we address some limitations concerning an interesting new study that warrants directions for future studies.