Effect of dexmedetomidine versus lorazepam on outcome in patients with sepsis: an a priori-designed analysis of the MENDS randomized controlled trial

Safety and Efficacy of Dexmedetomidine in Acutely Ill Adults Requiring Noninvasive Ventilation: A Systematic Review and Meta-analysis of Randomized Trials

BACKGROUND

Although clinical studies have evaluated dexmedetomidine as a strategy to improve noninvasive ventilation (NIV) comfort and tolerance in patients with acute respiratory failure (ARF), their results have not been summarized.

RESEARCH QUESTION

Does dexmedetomidine, when compared with another sedative or placebo, reduce the risk of delirium, mortality, need for intubation and mechanical ventilation, or ICU length of stay (LOS) in adults with ARF initiated on NIV in the ICU?

STUDY DESIGN AND METHODS

We electronically searched MEDLINE, EMBASE, and the Cochrane Library from inception through July 31, 2020, for randomized clinical trials (RCTs). We calculated pooled relative risks (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes with the corresponding 95% CIs using a random-effect model.

RESULTS

Twelve RCTs were included in our final analysis (n = 738 patients). The use of dexmedetomidine, compared with other sedation strategies or placebo, reduced the risk of intubation (RR, 0.54; 95% CI, 0.41-0.71; moderate certainty), delirium (RR, 0.34; 95% CI, 0.22-0.54; moderate certainty), and ICU LOS (MD, -2.40 days; 95% CI, -3.51 to -1.29 days; low certainty). Use of dexmedetomidine was associated with an increased risk of bradycardia (RR, 2.80; 95% CI, 1.92-4.07; moderate certainty) and hypotension (RR, 1.98; 95% CI, 1.32-2.98; moderate certainty).

INTERPRETATION

Compared with any sedation strategy or placebo, dexmedetomidine reduced the risk of delirium and the need for mechanical ventilation while increasing the risk of bradycardia and hypotension. The results are limited by imprecision, and further large RCTs are needed.

TRIAL REGISTRY

PROSPERO; No.: 175086; URL: www.crd.york.ac.uk/prospero/.

How should dexmedetomidine and clonidine be prescribed in the critical care setting?

Cardiac, ventilatory and kidney management in the critical care setting has been optimized over the past decades. Cognition and sedation represent one of the last remaning challenges. As conventional sedation is suboptimal and as the sedation evoked by alpha-2 adrenergic agonists ("cooperative" sedation with dexmedetomidine, clonidine or guanfacine) represents a valuable alternative, this manuscript covers three practical topics for which evidence-based medicine is lacking: a) Switching from conventional to cooperative sedation ("switching"): the short answer is the abrupt withdrawal of conventional sedation, immediate implementation of alpha-2 agonist infusion and the use of "rescue sedation" (midazolam bolus[es]) or "breakthrough sedation" (haloperidol bolus[es]) to stabilize cooperative sedation. b) Switching from conventional to cooperative sedation in unstable patients (e.g., refractory delirium tremens, septic shock, acute respiratory distress syndrome, etc.): to avoid hypotension and bradycardia evoked by sympathetic deactivation, the short answer is to maintain the stroke volume through volume loading, vasopressors and inotropes. c) To avoid these switches and associated difficulties, alpha-2 agonists may be considered first-line sedatives. The short answer is to administer alpha-2 agonists slowly from admission or endotracheal intubation up to stabilized cooperative sedation. The "take home" message is as follows: a) alpha-2 agonists are jointly sympathetic deactivators and sedative agents; b) sympathetic deactivation implies maintaining the stroke volume and iterative assessment of volemia. Evidence-based medicine should document our propositions.

Effect of dexmedetomidine on delirium during sedation in adult patients in intensive care units: A systematic review and meta-analysis

STUDY OBJECTIVE

To compare the effect of sedation protocols with and without dexmedetomidine on delirium risk and duration in adult patients in intensive care units (ICUs).

DESIGN

A meta-analysis of randomized controlled trials.

REVIEW METHODS

We searched the Cochrane Central Register of Controlled Trials, PubMed, EMBASE, and ISI Web of Science from inception to September 3, 2020. We included studies comparing the effect of dexmedetomidine-based sedation on delirium risk with non-dexmedetomidine-based sedation in adult patients in ICUs. We pooled the data using a random-effects model using Review Manager 5.2, and assessed publication bias using Stata 11.0. The quality of evidence was rated using the Grading of Recommendations, Assessment, Development and Evaluation system.

MAIN RESULTS

We included 36 studies involving 9623 participants. The use of dexmedetomidine was associated with reduced risk of delirium (risk ratio [RR], 0.63; 95% confidence interval [CI], 0.54-0.75; very low-quality evidence), but higher incidences of hypotension and bradycardia during hospital stay. Dexmedetomidine was also associated with shorter durations of ICU stay, hospital stay and mechanical ventilation. Dexmedetomidine did not affect ICU mortality (RR, 1.01; 95% CI, 0.89-1.14; low-quality evidence), hospital mortality (RR, 1.01; 95% CI, 0.91-1.12; very low-quality evidence), or 30-day mortality (RR, 0.77; 95% CI, 0.58-1.01; moderate-quality evidence), or duration of delirium (mean difference, -0.74 days; 95% CI, -1.83 to 0.36 days; very low-quality evidence). We identified publication bias for risk and duration of delirium, length of ICU stay, and hospital stay.

CONCLUSIONS

Low- or very low-quality evidence suggests that dexmedetomidine was associated with a clinically-small reduction of delirium risk, ICU/hospital stay and mechanical ventilation duration, but were not associated with improved mortality or shorter delirium duration in ICU patients. These findings were inconclusive because of publication bias, heterogeneity, and limited sample size. Significant adverse effects of dexmedetomidine include hypotension and bradycardia. PROSPERO registration number: CRD42018095358.

Clinical Practice: Should we Radically Alter our Sedation of Critical Care Patients, Especially Given the COVID-19 Pandemics?

The high number of patients infected with the SARS-CoV-2 virus requiring care for ARDS puts sedation in the critical care unit (CCU) to the edge. Depth of sedation has evolved over the last 40 years (no-sedation, deep sedation, daily emergence, minimal sedation, etc.). Most guidelines now recommend determining the depth of sedation and minimizing the use of benzodiazepines and opioids. The broader use of alpha-2 adrenergic agonists ('alpha-2 agonists') led to sedation regimens beginning at admission to the CCU that contrast with hypnotics+opioids ("conventional" sedation), with major consequences for cognition, ventilation and circulatory performance. The same doses of alpha-2 agonists used for 'cooperative' sedation (ataraxia, analgognosia) elicit no respiratory depression but modify the autonomic nervous system (cardiac parasympathetic activation, attenuation of excessive cardiac and vasomotor sympathetic activity). Alpha-2 agonists should be selected only in patients who benefit from their effects ('personalized' indications, as opposed to a 'one size fits all' approach). Then, titration to effect is required, especially in the setting of systemic hypotension and/or hypovolemia. Since no general guidelines exist for the use of alpha-2 agonists for CCU sedation, our clinical experience is summarized for the benefit of physicians in clinical situations in which a recommendation might never exist (refractory delirium tremens; unstable, hypovolemic, hypotensive patients, etc.). Because the physiology of alpha-2 receptors and the pharmacology of alpha-2 agonists lead to personalized indications, some details are offered. Since interactions between conventional sedatives and alpha-2 agonists have received little attention, these interactions are addressed. Within the existing guidelines for CCU sedation, this article could facilitate the use of alpha-2 agonists as effective and safe sedation while awaiting large, multicentre trials and more evidence-based medicine.

Evolving targets for sedation during mechanical ventilation

PURPOSES OF REVIEW

Critically ill patients frequently require mechanical ventilation as part of their care. Administration of analgesia and sedation to ensure patient comfort and facilitate mechanical ventilation must be balanced against the known negative consequences of excessive sedation. The present review focuses on the current evidence for sedation management during mechanical ventilation, including choice of sedatives, sedation strategies, and special considerations for acute respiratory distress syndrome (ARDS).

RECENT FINDINGS

The Society of Critical Care Medicine recently published their updated clinical practice guidelines for analgesia, agitation, sedation, delirium, immobility, and sleep in adult patients in the ICU. Deep sedation, especially early in the course of mechanical ventilation, is associated with prolonged time to liberation from mechanical ventilation, longer ICU stays, longer hospital stays, and increased mortality. Dexmedetomidine may prevent ICU delirium when administered nocturnally at low doses; however, it was not shown to improve mortality when used as the primary sedative early in the course of mechanical ventilation, though the majority of patients in the informing study failed to achieve the prescribed light level of sedation. In a follow up to the ACURASYS trial, deep sedation with neuromuscular blockade did not result in improved mortality compared to light sedation in patients with severe ARDS.

SUMMARY

Light sedation should be targeted early in the course of mechanical ventilation utilizing daily interruptions of sedation and/or nursing protocol-based algorithms, even in severe ARDS.

Sepsis-Associated Brain Dysfunction: A Review of Current Literature

Sepsis-associated brain dysfunction (SABD) may be the most common type of encephalopathy in critically ill patients. SABD develops in up to 70% of septic patients and represents the most frequent organ insufficiency associated with sepsis. It presents with a plethora of acute neurological features and may have several serious long-term psychiatric consequences. SABD might cause various pathological changes in the brain through numerous mechanisms. Clinical neurological examination is the basic screening method for SABD, although it may be challenging in subjects receiving with opioids and sedative agents. As electrographic seizures and periodic discharges might be present in 20% of septic patients, screening with electroencephalography (EEG) might be useful. Several imaging techniques have been suggested for non-invasive assessment of structure and function of the brain in SABD patients; however, their usefulness is rather limited. Although several experimental therapies have been postulated, at the moment, no specific treatment exists. Clinicians should focus on preventive measures and optimal management of sepsis. This review discusses epidemiology, clinical presentation, pathology, pathophysiology, diagnosis, management, and prevention of SABD.

Dexmedetomidine and Mortality From Sepsis Requiring Mechanical Ventilation: A Japanese Nationwide Retrospective Cohort Study

BACKGROUND

Dexmedetomidine has a mild sedative effect and may reduce mortality in mechanically ventilated critically ill patients. However, few studies have examined the effects of dexmedetomidine in patients with sepsis who require mechanical ventilation. The aim of this study was to investigate the association between dexmedetomidine and mortality in patients with sepsis requiring mechanical ventilation, using a nationwide inpatient database in Japan.

METHODS

Using the Diagnosis Procedure Combination database from July 1, 2010, to March 31, 2016, we identified adult patients with sepsis who required mechanical ventilation for more than 2 days. Patients were divided into those who received dexmedetomidine and those who received midazolam or propofol within 1 day after admission. Logistic regression analysis, propensity score-matched analysis, and instrumental variable analysis were performed to compare all-cause 28-day mortality and duration of mechanical ventilation between the groups.

RESULTS

In total, 50 671 were eligible patients, including dexmedetomidine group (n = 13 759) and propofol or midazolam group (n = 36 912). The dexmedetomidine group had significantly lower all-cause 28-day mortality compared with the group receiving midazolam or propofol, as shown by the logistic regression analysis (odds ratio [OR]: 0.78; 95% confidence interval [CI]: 0.73-0.84), the propensity score-matched analysis (OR: 0.85; 95% CI: 0.80-0.91), and the instrumental variable analysis (OR: 0.64; 95% CI: 0.57-0.73). The duration of mechanical ventilation in the dexmedetomidine group was significantly shorter than that in the midazolam or propofol group.

CONCLUSIONS

Dexmedetomidine was associated with a reduction in all-cause 28-day mortality and duration of mechanical ventilation.

The effect of dexmedetomidine on vasopressor requirements in patients with septic shock: a subgroup analysis of the Sedation Practice in Intensive Care Evaluation [SPICE III] Trial

BACKGROUND

Septic shock is associated with decreased vasopressor responsiveness. Experimental data suggest that central alpha2-agonists like dexmedetomidine (DEX) increase vasopressor responsiveness and reduce catecholamine requirements in septic shock. However, DEX may also cause hypotension and bradycardia. Thus, it remains unclear whether DEX is hemodynamically safe or helpful in this setting.

METHODS

In this post hoc subgroup analysis of the Sedation Practice in Intensive Care Evaluation (SPICE III) trial, an international randomized trial comparing early sedation with dexmedetomidine to usual care in critically patients receiving mechanical ventilation, we studied patients with septic shock admitted to two tertiary ICUs in Australia and Switzerland. The primary outcome was vasopressor requirements in the first 48 h after randomization, expressed as noradrenaline equivalent dose (NEq [μg/kg/min] = noradrenaline + adrenaline + vasopressin/0.4).

RESULTS

Between November 2013 and February 2018, 417 patients were recruited into the SPICE III trial at both sites. Eighty-three patients with septic shock were included in this subgroup analysis. Of these, 44 (53%) received DEX and 39 (47%) usual care. Vasopressor requirements in the first 48 h were similar between the two groups. Median NEq dose was 0.03 [0.01, 0.07] μg/kg/min in the DEX group and 0.04 [0.01, 0.16] μg/kg/min in the usual care group (p = 0.17). However, patients in the DEX group had a lower NEq/MAP ratio, indicating lower vasopressor requirements to maintain the target MAP. Moreover, on adjusted multivariable analysis, higher dexmedetomidine dose was associated with a lower NEq/MAP ratio.

CONCLUSIONS

In critically ill patients with septic shock, patients in the DEX group received similar vasopressor doses in the first 48 h compared to the usual care group. On multivariable adjusted analysis, dexmedetomidine appeared to be associated with lower vasopressor requirements to maintain the target MAP.

TRIAL REGISTRATION

The SPICE III trial was registered at ClinicalTrials.gov ( NCT01728558 ).

Dexmedetomidine Exerts an Anti-inflammatory Effect via α2 Adrenoceptors to Prevent Lipopolysaccharide-induced Cognitive Decline in Mice

Background

Clinical studies have shown that dexmedetomidine ameliorates cognitive decline in both the postoperative and critical care settings. This study determined the mechanism(s) for the benefit provided by dexmedetomidine in a medical illness in mice induced by lipopolysaccharide.

Methods

Cognitive decline, peripheral and hippocampal inflammation, blood–brain barrier permeability, and inflammation resolution were assessed in male mice. Dexmedetomidine was administered in the presence of lipopolysaccharide and in combination with blockers. Cultured macrophages (RAW 264.7; BV-2) were exposed to lipopolysaccharide ± dexmedetomidine ± yohimbine; tumor necrosis factor α release into the medium and monocyte NFκB activity was determined.

Results

In vivo, lipopolysaccharide-induced cognitive decline and inflammation (mean ± SD) were reversed by dexmedetomidine (freezing time, 55.68 ± 12.31 vs. 35.40 ± 17.66%, P = 0.0286, n = 14; plasma interleukin [IL]-1β: 30.53 ± 9.53 vs. 75.68 ± 11.04 pg/ml, P < 0.0001; hippocampal IL-1β: 3.66 ± 1.88 vs. 28.73 ± 5.20 pg/mg, P < 0.0001; n = 8), which was prevented by α2 adrenoceptor antagonists. Similar results were found in 12-month-old mice. Lipopolysaccharide also increased blood–brain barrier leakage, inflammation-resolution orchestrator, and proresolving and proinflammatory mediators; each lipopolysaccharide effect was attenuated by dexmedetomidine, and yohimbine prevented dexmedetomidine’s attenuating effect. In vitro, lipopolysaccharide-induced tumor necrosis factor α release (RAW 264.7: 6,308.00 ± 213.60 vs. 7,767.00 ± 358.10 pg/ml, P < 0.0001; BV-2: 1,075.00 ± 40.41 vs. 1,280.00 ± 100.30 pg/ml, P = 0.0003) and NFκB–p65 activity (nuclear translocation [RAW 264.7: 1.23 ± 0.31 vs. 2.36 ± 0.23, P = 0.0031; BV-2: 1.08 ± 0.26 vs. 1.78 ± 0.14, P = 0.0116]; phosphorylation [RAW 264.7: 1.22 ± 0.40 vs. 1.94 ± 0.23, P = 0.0493; BV-2: 1.04 ± 0.36 vs. 2.04 ± 0.17, P = 0.0025]) were reversed by dexmedetomidine, which was prevented by yohimbine.

Conclusions

Preclinical studies suggest that the cognitive benefit provided by dexmedetomidine in mice administered lipopolysaccharide is mediated through α2 adrenoceptor–mediated anti-inflammatory pathways.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Sepsis Associated Delirium

Sepsis is a potentially life-threatening condition caused by a systemic dysregulated host response to infection. The brain is particularly susceptible to the effects of sepsis with clinical manifestations ranging from mild confusion to a deep comatose state. Sepsis-associated delirium (SAD) is a cerebral manifestation commonly occurring in patients with sepsis and is thought to occur due to a combination of neuroinflammation and disturbances in cerebral perfusion, the blood brain barrier (BBB) and neurotransmission. The neurological impairment associated with SAD can persist for months or even longer, after the initial septic episode has subsided which may impair the rehabilitation potential of sepsis survivors. Early identification and treatment of the underlying sepsis is key in the management of SAD as once present it can be difficult to control. Through the regular use of validated screening tools for delirium, cases of SAD can be identified early; this allows potentially aggravating factors to be addressed promptly. The usefulness of biomarkers, neuroimaging and electroencephalopathy (EEG) in the diagnosis of SAD remains controversial. The Society of Critical Care Medicine (SCCM) guidelines advise against the use of medications to treat delirium unless distressing symptoms are present or it is hindering the patient’s ability to wean from organ support.

Septic-Associated Encephalopathy: a Comprehensive Review

Septic-associated encephalopathy (SAE) is a key manifestation of sepsis, ranging from delirium to coma and occurring in up to 70% of patients admitted to the ICU. SAE is associated with higher ICU and hospital mortality, and also with poorer long-term outcomes, including cognitive and functional outcomes. The pathophysiology of SAE is complex, and it may involve neurotransmitter dysfunction, inflammatory and ischemic lesions to the brain, microglial activation, and blood-brain barrier dysfunction. Delirium (which is included in the SAE spectrum) is mostly diagnosed with validated scales in the ICU population. There is no established treatment for SAE; benzodiazepines should generally be avoided in this setting. Nonpharmacological prevention and management is key for treating SAE; it includes avoiding oversedation (mainly with benzodiazepines), early mobilization, and sleep promotion.

Sepsis-Associated Encephalopathy: From Delirium to Dementia?

Sepsis is a major cause of death in intensive care units worldwide. The acute phase of sepsis is often accompanied by sepsis-associated encephalopathy, which is highly associated with increased mortality. Moreover, in the chronic phase, more than 50% of surviving patients suffer from severe and long-term cognitive deficits compromising their daily quality of life and placing an immense burden on primary caregivers. Due to a growing number of sepsis survivors, these long-lasting deficits are increasingly relevant. Despite the high incidence and clinical relevance, the pathomechanisms of acute and chronic stages in sepsis-associated encephalopathy are only incompletely understood, and no specific therapeutic options are yet available. Here, we review the emergence of sepsis-associated encephalopathy from initial clinical presentation to long-term cognitive impairment in sepsis survivors and summarize pathomechanisms potentially contributing to the development of sepsis-associated encephalopathy.

Dexmedetomidine Pretreatment Improves Lipopolysaccharide-induced Iron Homeostasis Disorder in Aged Mice

BACKGROUND

Iron homeostasis disorder and neuroinflammation are the most commonly known factors that promote the occurrence and development of cognitive impairment in people. Dexmedetomidine has an anti-inflammatory effect, and it reduces the incidence of postoperative cognitive dysfunction. Therefore, the aim of this study is to verify whether dexmedetomidine could improve lipopolysaccharide-induced iron homeostasis disorder in aged mice, and show neuroprotective effect.

METHODS

First part, forty 12 month old male Kunming(KM) mice were divided into group N and group D: Normal saline group (group N), Dexmedetomidine group (group D). Second part, sixty 12-month-old male KM mice were divided into the following three groups: Normal saline group (group N), Lipopolysaccharide group (group LPS) and Dexmedetomidine + Lipopolysaccharide group (group D + LPS). The mice in group D + LPS were given dexmedetomidine, and given LPS intraperitoneally 2 h later. Mice underwent an oriented navigation test and a space exploration test in the Morris Water maze (MWM) test. The expression levels of Interleukin-6 ( IL-6), L-ferritin (FTL) and Transferrin receptor-1 (TfR1) in hippocampus were detected by the Western blot analysis; the hippocampal hepcidin mRNA was detected by Real-time PCR(RT-PCR); the reactive oxygen species (ROS) in the hippocampus was measured using ROS test kit.

RESULTS

Dexmedetomidine improved the cognitive decline induced by LPS. Dexmedetomidine reduced the level of hippocampal IL-6, and it attenuated the increase in their levels caused by LPS. It had no effect on hippocampal hepcidin mRNA, FTL, TfR1 and ROS but it could attenuate the increase caused by LPS.

CONCLUSION

Dexmedetomidine has no effect on iron metabolism pathway, but it can improve the cognitive decline and the iron disorder by reducing neuroinflammation and oxidative stress. The research indicates that dexmedetomidine plays a neuroprotective role.

Effect of Dexmedetomidine on duration of mechanical ventilation in septic patients: a systematic review and meta-analysis

Background

Because of its analgesic and light sedative properties, the highly selective alpha-2 adrenergic receptor agonist dexmedetomidine (DEX) has been suggested for the treatment of septic patients, but its effect on the duration of mechanical ventilation remains unclear. The present study was conducted to review the extant literature in DEX and determine its influence on ventilation time in adult septic patients.

Methods

Databases of PubMed, Cochrane, and EMBASE were applied till 20th January 2019 without language restriction. The searching strategy as following: sepsis OR septic AND mechanical ventilation AND dexmedetomidine. Two authors screened titles, abstracts, and even articles to meet the including criterion independently. In addition, references of related articles or reviews were also referred. Data was recorded in a table and analyzed using the software of Review Manager 5.0.

Results

Four studies with a total of 349 patients were included. Three trials with 267 patients revealed the effect of DEX on duration of mechanical ventilation, two trials with 264 patients on ventilator-free days and four trials with 334 patients on 28-day mortality. The analyzed results indicated that DEX was not associated with significantly different durations of mechanical ventilation (MD 0.65, 95% CI, − 0.13 to 1.42, P = 0.10). However, there were significant differences in ventilator-free days (MD 3.57, 95% CI, 0.26 to 6.89, P = 0.03) and 28-day mortality (RR 0.61, 95% CI, 0.49 to 0.94, P = 0.02) in the septic patients.

Conclusion

Administration of DEX for sedation in septic patients was not associated with the duration of mechanical ventilation, but it increased the ventilator-free days and reduced 28-day mortality.

Dexmedetomidine improved renal function in patients with severe sepsis: an exploratory analysis of a randomized controlled trial

Background

Dexmedetomidine has been reported to improve organ dysfunction in critically ill patients. In a recent randomized controlled trial (Dexmedetomidine for Sepsis in Intensive Care Unit (ICU) Randomized Evolution [DESIRE]), we demonstrated that dexmedetomidine was associated with reduced mortality risk among patients with severe sepsis. We performed this exploratory sub-analysis to examine the mechanism underlying improved survival in patients sedated with dexmedetomidine.

Methods

The DESIRE trial compared a sedation strategy with and without dexmedetomidine among 201 mechanically ventilated adult patients with sepsis across eight ICUs in Japan. In the present study, we included 104 patients with Acute Physiology and Chronic Health Evaluation II (APACHE II) scores of ≥ 23 (54 in the dexmedetomidine [DEX] group and 50 in the non-dexmedetomidine [non-DEX] group). Initially, we compared the changes in the sequential organ failure assessment (SOFA) scores from the baseline within 6 days after randomization between groups. Subsequently, we evaluated the variables comprising the organ component of the SOFA score that showed relevant improvement in the initial comparison.

Results

The mean patient age was 71.0 ± 14.1 years. There was no difference in the median APACHE II score between the two groups (29 [interquartile range (IQR), 25–31] vs. 30 [IQR, 25–33]; p = 0.35). The median SOFA score at the baseline was lower in the DEX group (9 [IQR, 7–11] vs. 11 [IQR, 9–13]; p = 0.01). While the renal SOFA subscore at the baseline was similar for both groups, it significantly decreased in the DEX group on day 4 (p = 0.02). During the first 6 days, the urinary output was not significantly different (p = 0.09), but serum creatinine levels were significantly lower (p = 0.04) in the DEX group. The 28-day and in-hospital mortality rates were significantly lower in the DEX group (22% vs. 42%; p = 0.03, 28% vs. 52%; p = 0.01, respectively).

Conclusion

A sedation strategy with dexmedetomidine is associated with improved renal function and decrease mortality rates among patients with severe sepsis.

Trial registration

This trial was registered on ClinicalTrials.gov (NCT01760967) on January 1, 2013.

Circulatory effects of dexmedetomidine in early sepsis: a randomised controlled experimental study

We designed this experimental study with a view to evaluate the effects of dexmedetomidine (DEX) on cardiac performance and systemic and peripheral hemodynamics in healthy and early-stage endotoxemia swine models. Our study hypothesis was that DEX can ensure hemodynamic stability during the course of endotoxemia. Thirty-two male pigs (25-27 kg) were assigned into four groups: (1) no intervention (group A), (2) DEX 0.8 μg/kg was administered in non-septic animals (group B), (3) sepsis induced by intravenous Escherichia coli endotoxin (group C) and (4) DEX 0.8 μg/kg was administered in septic animals (group D). Hemodynamic parameters such as heart rate, mean blood pressure, central venous pressure, pulmonary artery pressures, pulmonary artery occlusion pressure, pulmonary vascular resistance and cardiac output were continuously recorded. Central venous oxygen saturation was also measured in order to obtain a complete evaluation of cardiovascular response to sepsis. Heart rate was decreased, whilst mean arterial pressure decrease was alleviated after DEX administration in septic animals. In addition, central venous pressure was stable in animals with sepsis after DEX infusion. Sepsis dramatically elevated pulmonary function indicators but DEX succeeded in ameliorating this effect. The important decrease measured in central venous oxygen saturation in both sepsis groups reflected the decreased perfusion of tissues that takes place at the end of early sepsis. Our findings support the hypothesis that DEX has beneficial effects on heart rate and pulmonary artery pressure, whilst reduction in systemic blood pressure occurs at acceptable levels.

Neurological dysfunction after cardiac surgery and cardiac intensive care admission: A narrative review part 2: Cognitive dysfunction after critical illness; potential contributors in surgery and intensive care; pathogenesis; and therapies to prevent/treat perioperative neurological dysfunction

Severe cognitive decline and cognitive dysfunction has been attributed to patient's stay in the cardiovascular intensive care unit. Prolonged mechanical ventilation, long duration of stay, sedation protocols, and sleep deprivation contribute to patients developing neurocognitive disorder after intensive care admission and it is associated with poor clinical outcomes. Trauma of surgery, stress of critical care, and administration of anaesthesia evoke a systemic inflammatory response and trigger neuroinflammation and oxidative stress. Anaesthetic agents modulate the function of the GABA receptors. The persistence of these effects in the postoperative period promotes development of cognitive dysfunction. A number of drugs are under investigation to restrict or prevent this cognitive decline.

Effects of sepsis on hippocampal volume and memory function

BACKGROUND

This study aimed to determine the effects of sepsis on brain integrity, memory, and executive function.

METHODS

Twenty sepsis patients who were not diagnosed with sepsis-associated encephalopathy (SAE) but had abnormal electroencephalograms (EEGs) were included. The control group included twenty healthy persons. A neuropsychological test of memory and executive function and a brain magnetic resonance imaging scan were performed. The volumes of cortex and subcortex were measured using the FreeSurfer software. Acute Physiology and Chronic Health Evaluation II (APACHE II) score was used to determine the disease severity.

RESULTS

In the sepsis group, the levels of immediate free recall, immediate cued recall, and delayed cued recall in the California Verbal Learning Test-II (CVLT-II) were significantly lower; the explicit memory (recollection process) in the process dissociation procedure test was lower; and the volumes of the left and right hippocampi were significantly lower compared with the control group. The volume of the presubiculum in the hippocampus of sepsis patients showed statistically significant decrease. In the sepsis group, the volumes of the left and right hippocampi were negatively correlated with the APACHE II score and positively with immediate free recall, immediate cued recall, and delayed cued recall in the CVLT-II; moreover, the hippocampal volume was significantly correlated with recollection but not with familiarity.

CONCLUSIONS

Patients with abnormal EEGs during hospitalization but with no SAE still have reduced hippocampal volume and memory deficits. This finding indicates that sepsis leads to damage to specific parts of the hippocampus.

The effect of dexmedetomidine and clonidine on the inflammatory response in critical illness: a systematic review of animal and human studies

Background

The α2 agonists, dexmedetomidine and clonidine, are used as sedative drugs during critical illness. These drugs may have anti-inflammatory effects, which might be relevant to critical illness, but a systematic review of published literature has not been published. We reviewed animal and human studies relevant to critical illness to summarise the evidence for an anti-inflammatory effect from α2 agonists.

Methods

We searched PubMed, the Cochrane library, and Medline. Animal and human studies published in English were included. Broad search terms were used: dexmedetomidine or clonidine, sepsis, and inflammation. Reference lists were screened for additional publications. Titles and abstracts were screened independently by two reviewers and full-text articles obtained for potentially eligible studies. Data extraction used a bespoke template given study diversity, and quality assessment was qualitative.

Results

Study diversity meant meta-analysis was not feasible so descriptive synthesis was undertaken. We identified 30 animal studies (caecal ligation/puncture (9), lipopolysaccharide (14), acute lung injury (5), and ischaemia-reperfusion syndrome (5)), and 9 human studies. Most animal (26 dexmedetomidine, 4 clonidine) and all human studies used dexmedetomidine. In animal studies, α2 agonists reduced serum and/or tissue TNFα (20 studies), IL-6 (17 studies), IL-1β (7 studies), NFκB (6 studies), TLR4 (6 studies), and a range of other mediators. Timing and doses varied widely, but in many cases were not directly relevant to human sedation use. In human studies, dexmedetomidine reduced CRP (4 studies), TNFα (5 studies), IL-6 (6 studies), IL-1β (3 studies), and altered several other mediators. Most studies were small and low quality. No studies related effects to clinical outcomes.

Conclusion

Evidence supports potential anti-inflammatory effects from α2 agonists, but the relevance to clinically important outcomes is uncertain. Further work should explore whether dose relationships with inflammation and clinical outcomes are present which might be separate from sedation-mediated effects.

The influence of dexmedetomidine and propofol on circulating cytokine levels in healthy subjects

Background

Surgery and diseases modify inflammatory responses and the immune system. Anesthetic agents also have effects on the human immune system but the responses they induce may be altered or masked by the surgical procedures or underlying illnesses. The aim of this study was to assess how single-drug dexmedetomidine and propofol anesthesia without any surgical intervention alter acute immunological biomarkers in healthy subjects.

Methods

Thirty-five healthy, young male subjects were anesthetized using increasing concentrations of dexmedetomidine (n = 18) or propofol (n = 17) until loss of responsiveness (LOR) was detected. The treatment allocation was randomized. Multi-parametric immunoassays for the detection of 48 cytokines, chemokines and growth factors were used. Concentrations were determined at baseline and at the highest drug concentration for each subject.

Results

The changes in the concentration of eotaxin (decrease after dexmedetomidine) and platelet-derived growth factor (PDGF, increase after propofol) were statistically significantly different between the groups. Significant changes were detected within both groups; the concentrations of monocyte chemotactic protein 1, chemokine ligand 27 and macrophage migration inhibitory factor were lower in both groups after the drug administration. Dexmedetomidine decreased the concentration of eotaxin, interleukin-18, interleukin-2Rα, stem cell factor, stem cell growth factor and vascular endothelial growth factor, and propofol decreased significantly the levels of hepatocyte growth factor, IFN-γ-induced protein 10 and monokine induced by IFN-γ, and increased the levels of interleukin-17, interleukin-5, interleukin-7 and PDGF.

Conclusions

Dexmedetomidine seemed to have an immunosuppressive effect on the immune system whereas propofol seemed to induce mixed pro- and anti-inflammatory effects on the immune system. The choice of anesthetic agent could be relevant when treating patients with compromised immunological defense mechanisms.

Trial registration

Before subject enrollment, the study was registered in the European Clinical Trials database (EudraCT number 2013–001496-21, The Neural Mechanisms of Anesthesia and Human Consciousness) and in ClinicalTrials.gov (Principal Investigator: Harry Scheinin, number NCT01889004, The Neural Mechanisms of Anesthesia and Human Consciousness, Part 2, on the 23rd of June 2013).

Reconsidering Dexmedetomidine for Sedation in the Critically Ill: Implications of the SPICE III Trial

Dexmedetomidine is a sedative agent that has gained popularity for use in the intensive care unit over the past 20 years. Guidelines recommend dexmedetomidine as a first-line agent to achieve light sedation in mechanically ventilated adults. Recently, the SPICE III (Sedation Practice in Intensive Care Evaluation III) trial was published. This was a randomized controlled trial comparing initial sedation with dexmedetomidine with usual care sedation in adult patients receiving mechanical ventilation. The results of this trial have both validated and contradicted previous findings about dexmedetomidine. This editorial examines the merits of the SPICE III trial and the role of dexmedetomidine in practice following its publication.

Postoperative acute respiratory failure in cardiac surgery

OBJECTIVE

To evaluate incidence, causes and outcomes of acute respiratory failure (ARF) in patients after cardiac and aortic surgery.

MATERIAL AND METHODS

A retrospective trial included 3972 patients after elective cardiovascular procedures for the period 2013-2017. Inclusion criterion: sustained reduction of pulmonary function (PaO₂/FiO₂<300 mm Hg) in the postoperative period required mechanical ventilation or non-invasive positive pressure mask ventilation for at least 24 h.

RESULTS

ARF developed in 138 (3.5%) cases. It was observed after aortic surgery as a rule (11.2%). Other operations were followed by ARF in 1-3.5% of cases. Incidence of ARF was less after off-pump coronary artery bypass surgery compared with on-pump interventions (1.6 vs. 3.5%, p=0.0469). Acute respiratory distress syndrome was the main reason of ARF (n=37, 26.8%). ARF as a consequence of neurological complications were observed in 25 (18.1%) patients. Exacerbation of COPD and bronchial asthma occurred in 23 (16.1%) patients, paresis of the diaphragm - in 15 (11.7%). In 15 (10.8%) patients, ARF was caused by pneumonia, in 12 (8.7%) cases - pulmonary congestion, in 10 (7.2%) patients - lung injury and haemothorax. Overall ARDS-associated mortality was 21.6%; 15.1% of patients with mild and moderate ARDS died. Severe ARDS was followed by unfavorable outcome in 75% of patients. Nosocomial pneumonia was found in 40.6%, there were no fatal outcomes from this complication.

CONCLUSION

Acute respiratory failure developed in 3.5% of cardiac patients and was common thoracic and thoracoabdominal aortic surgery. The leading cause of mortality was ARDS (mortality rate 15.1% in mild and moderate syndrome, 75% in severe course of ARDS). Nosocomial pneumonia was diagnosed in 1.4% of patients and was not fatal.

Effect of Dexmedetomidine on Lactate Clearance in Patients With Septic Shock: A Subanalysis of a Multicenter Randomized Controlled Trial

Lactate clearance is useful to guide initial resuscitation of patients with septic shock. We conducted this study to evaluate whether dexmedetomidine increases lactate clearance in patients with septic shock. This was a randomized controlled trial that involved a post hoc subgroup analysis. Adult patients with septic shock under ventilation were randomized to receive sedation strategy with or without dexmedetomidine (60 in the dexmedetomidine and 51 in the nondexmedetomidine groups). The primary outcome was the lactate clearance at 6 h, defined as the percent decrease in lactate from randomization to 6 h after. The median Acute Physiology and Chronic Health Evaluation II score was 25 (interquartile range 19-31). The median serum lactate value at randomization was lower in the dexmedetomidine group than in the nondexmedetomidine group (4.0 mmol/L vs. 4.8 mmol/L; P = 0.053). The lactate clearance at 6 h was higher in the dexmedetomidine group, although this was not statistically significant (23.3 ± 29.8 vs. 11.1 ± 54.4, mean difference 12.2, 95% confidence interval (CI), -4.4 to 28.8). After adjusting for the lactate level at randomization, lactate clearance at 6 h was significantly higher in the dexmedetomidine group (adjusted mean difference 18.5, 95% CI, 2.2-34.9). There was no statistically significant difference in the 28-day mortality between the dexmedetomidine and the nondexmedetomidine groups (13 [22%] vs. 18 [35%] patients, P = 0.11). In conclusion, among mechanically ventilated patients with septic shock, sedation with dexmedetomidine resulted in increased lactate clearance compared with sedation without dexmedetomidine.

[Protective effects of dexmedetomidine against pulmonary ischemia-reperfusion injury during cardiopulmonary bypass in rats]

OBJECTIVE

To investigate the signaling pathways that mediate the protective effects of dexmedetomidine on lung tissue against ischemia-reperfusion (I/R) injury during cardiopulmonary bypass (CPB).

METHODS

Forty adult SD rats were randomized into 5 groups, namely I/R group (group A), dexmedetomidine group (group B), sham-operated group (group C), oxypenicillin group (group D), and oxypenicillin + dexmedetomidine group (group E). The arterial blood gas, lung tissue apoptosis rate, protein kinase (Akt), phosphorylated Akt (p-AKT), caspase-3 and caspase-9 were compared among the 5 groups.

RESULTS

In groups A, B, D and E, the heart rate (HR), mean arterial pressure (MAP), and oxygenation index (OI) measured before CPB, at opening of the left hilar and at the end of experiment decreased gradually while the respiratory index (RI) increased at the 3 time points. At the end of experiment, HR, MAP, and OI in group B were significantly higher and RI was significantly lower than those in groups A, D and E (P &lt; 0.05). In groups A-E, the pathological scores of the lung tissue at the end of the experiment were 4.89, 1.89, 0, 6.01 and 5.76, respectively, and the cell apoptosis rates in the lung tissue were 6.25%, 3.69%, 1.06%, 8.06% and 7.79%, respectively (P &lt; 0.001). Western blotting showed that the expressions of Akt and p-AKT were the highest and those of caspase-3 and caspase-9 were the lowest in group B among the 5 groups (P &lt; 0.05).

CONCLUSIONS

Dexmedetomidine can effectively alleviate lung injury in rats during CPB possibly by targeting caspase-3 and caspase-9 proteins that are related to PI3K/Akt signaling pathway.

Dexmedetomidine Prevents Cognitive Decline by Enhancing Resolution of High Mobility Group Box 1 Protein-induced Inflammation through a Vagomimetic Action in Mice

BACKGROUND

Inflammation initiated by damage-associated molecular patterns has been implicated for the cognitive decline associated with surgical trauma and serious illness. We determined whether resolution of inflammation mediates dexmedetomidine-induced reduction of damage-associated molecular pattern-induced cognitive decline.

METHODS

Cognitive decline (assessed by trace fear conditioning) was induced with high molecular group box 1 protein, a damage-associated molecular pattern, in mice that also received blockers of neural (vagal) and humoral inflammation-resolving pathways. Systemic and neuroinflammation was assessed by proinflammatory cytokines.

RESULTS

Damage-associated molecular pattern-induced cognitive decline and inflammation (mean ± SD) was reversed by dexmedetomidine (trace fear conditioning: 58.77 ± 8.69% vs. 41.45 ± 7.64%, P < 0.0001; plasma interleukin [IL]-1β: 7.0 ± 2.2 pg/ml vs. 49.8 ± 6.0 pg/ml, P < 0.0001; plasma IL-6: 3.2 ± 1.6 pg/ml vs. 19.5 ± 1.7 pg/ml, P < 0.0001; hippocampal IL-1β: 4.1 ± 3.0 pg/mg vs. 41.6 ± 8.0 pg/mg, P < 0.0001; hippocampal IL-6: 3.4 ± 1.3 pg/mg vs. 16.2 ± 2.7 pg/mg, P < 0.0001). Reversal by dexmedetomidine was prevented by blockade of vagomimetic imidazoline and α7 nicotinic acetylcholine receptors but not by α2 adrenoceptor blockade. Netrin-1, the orchestrator of inflammation-resolution, was upregulated (fold-change) by dexmedetomidine (lung: 1.5 ± 0.1 vs. 0.7 ± 0.1, P < 0.0001; spleen: 1.5 ± 0.2 vs. 0.6 ± 0.2, P < 0.0001), resulting in upregulation of proresolving (lipoxin-A4: 1.7 ± 0.2 vs. 0.9 ± 0.2, P < 0.0001) and downregulation of proinflammatory (leukotriene-B4: 1.0 ± 0.2 vs. 3.0 ± 0.3, P < 0.0001) humoral mediators that was prevented by α7 nicotinic acetylcholine receptor blockade.

CONCLUSIONS

Dexmedetomidine resolves inflammation through vagomimetic (neural) and humoral pathways, thereby preventing damage-associated molecular pattern-mediated cognitive decline.

Early Sedation with Dexmedetomidine in Critically Ill Patients

BACKGROUND

Dexmedetomidine produces sedation while maintaining a degree of arousability and may reduce the duration of mechanical ventilation and delirium among patients in the intensive care unit (ICU). The use of dexmedetomidine as the sole or primary sedative agent in patients undergoing mechanical ventilation has not been extensively studied.

METHODS

In an open-label, randomized trial, we enrolled critically ill adults who had been undergoing ventilation for less than 12 hours in the ICU and were expected to continue to receive ventilatory support for longer than the next calendar day to receive dexmedetomidine as the sole or primary sedative or to receive usual care (propofol, midazolam, or other sedatives). The target range of sedation-scores on the Richmond Agitation and Sedation Scale (which is scored from -5 [unresponsive] to +4 [combative]) was -2 to +1 (lightly sedated to restless). The primary outcome was the rate of death from any cause at 90 days.

RESULTS

We enrolled 4000 patients at a median interval of 4.6 hours between eligibility and randomization. In a modified intention-to-treat analysis involving 3904 patients, the primary outcome event occurred in 566 of 1948 (29.1%) in the dexmedetomidine group and in 569 of 1956 (29.1%) in the usual-care group (adjusted risk difference, 0.0 percentage points; 95% confidence interval, -2.9 to 2.8). An ancillary finding was that to achieve the prescribed level of sedation, patients in the dexmedetomidine group received supplemental propofol (64% of patients), midazolam (3%), or both (7%) during the first 2 days after randomization; in the usual-care group, these drugs were administered as primary sedatives in 60%, 12%, and 20% of the patients, respectively. Bradycardia and hypotension were more common in the dexmedetomidine group.

CONCLUSIONS

Among patients undergoing mechanical ventilation in the ICU, those who received early dexmedetomidine for sedation had a rate of death at 90 days similar to that in the usual-care group and required supplemental sedatives to achieve the prescribed level of sedation. More adverse events were reported in the dexmedetomidine group than in the usual-care group. (Funded by the National Health and Medical Research Council of Australia and others; SPICE III ClinicalTrials.gov number, NCT01728558.).

Dexmedetomidine: present and future directions

Dexmedetomidine is a potent, highly selective α-2 adrenoceptor agonist, with sedative, analgesic, anxiolytic, sympatholytic, and opioid-sparing properties. Dexmedetomidine induces a unique sedative response, which shows an easy transition from sleep to wakefulness, thus allowing a patient to be cooperative and communicative when stimulated. Dexmedetomidine may produce less delirium than other sedatives or even prevent delirium. The analgesic effect of dexmedetomidine is not strong; however, it can be administered as a useful analgesic adjuvant. As an anesthetic adjuvant, dexmedetomidine decreases the need for opioids, inhalational anesthetics, and intravenous anesthetics. The sympatholytic effect of dexmedetomidine may provide stable hemodynamics during the perioperative period. Dexmedetomidine-induced cooperative sedation with minimal respiratory depression provides safe and acceptable conditions during neurosurgical procedures in awake patients and awake fiberoptic intubation. Despite the lack of pediatric labelling, dexmedetomidine has been widely studied for pediatric use in various applications. Most adverse events associated with dexmedetomidine occur during or shortly after a loading infusion. There are some case reports of dexmedetomidine-related cardiac arrest following severe bradycardia. Some extended applications of dexmedetomidine discussed in this review are promising, but still limited, and further research is required. The pharmacological properties and possible adverse effects of dexmedetomidine should be well understood by the anesthesiologist prior to use. Moreover, it is necessary to select patients carefully and to determine the appropriate dosage of dexmedetomidine to ensure patient safety.

Type D personality is a predictor of prolonged acute brain dysfunction (delirium/coma) after cardiovascular surgery

BACKGROUND

Previous studies have shown a relationship between delirium and depressive symptoms after cardiac surgery with distress personalities linking to negative surgical outcomes. The aim of the present study is to further investigate the association between patients with Type D (distressed) personality with regards to delirium after cardiac surgery.

METHODS

We conducted a consecutive-sample observational cohort pilot study with an estimated 142 patients needed. Enrollment criteria included patients aged ≥18 years who were undergoing planned cardiovascular, thoracic and abdominal artery surgery between October 2015 to August 2016 at the University of Tsukuba Hospital, Japan. All patients were screened by Type-D Personality Scale-14 (DS14) as well as the Hospital Anxiety and Depression Scale (HADS) the day before surgery. Following surgery, daily data was collected during recovery and included severity of organ dysfunction, sedative/analgesic exposure and other relevant information. We then evaluated the association between Type D personality and delirium/coma days (DCDs) during the 7-day study period. We applied regression and mediation modeling for this study.

RESULTS

A total of 142 patients were enrolled in the present study and the total prevalence of delirium was found to be 34% and 26% of the patients were Type D. Non-Type D personality patients experienced an average of 1.3 DCDs during the week after surgery while Type D patients experienced 2.1 days over the week after surgery. Multivariate analysis showed that Type D personality was significantly associated with increased DCDs (OR:2.8, 95%CI:1.3-6.1) after adjustment for depressive symptoms and clinical variables. Additionally, there was a significant Type D x depression interaction effect (OR:1.7, 95% CI:1.2-2.2), and depressive symptoms were associated with DCDs in Type D patients, but not in non-Type D patients. Mediation modeling showed that depressive symptoms partially mediated the association of Type D personality with DCDs (Aroian test =0.04).

CONCLUSIONS

Type D personality is a prognostic predictor for prolonged acute brain dysfunction (delirium/coma) in cardiovascular patients independent from depressive symptoms and Type D personality-associated depressive symptoms increase the magnitude of acute brain dysfunction.

Efficacy of dexmedetomidine for treatment of patients with sepsis: A meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis aimed to evaluate the effect of dexmedetomidine on prognosis in patients with sepsis.

METHODS

Computer-related electronic databases were searched, including PubMed, Embase, Web of Science, the Cochrane Library, and the China National Knowledge Infrastructure, from the date of database construction to January 2019. Stata 12.0 was used to perform a meta-analysis of short-term mortality [intensive care unit (ICU) mortality or 28-day mortality], ICU length of stay, and mechanical ventilation. Mortality was expressed using risk ratio (RR) and 95% confidence interval (CI). ICU length of stay and mechanical ventilation were expressed as weighted mean difference (WMD) and 95% CIs.

RESULTS

We finally included 8 randomized controlled trials in this meta-analysis. Compared with the control group, the dexmedetomidine group had a lower occurrence of 28-day mortality (RR, 0.49; 95% CI, 0.35 to 0.69; P = .000) and ICU mortality (RR, 0.44; 95% CI, 0.23 to 0.84; P = .013). However, there was no statistically significant difference for the length of hospital stay (WMD, -0.05; 95% CI, -0.59 to 0.48; P = .840) and mechanical ventilation time (WMD, 1.05; 95% CI, -0.27 to 2.37; P = .392) between dexmedetomidine group and control group.

CONCLUSIONS

In patients with sepsis, dexmedetomidine can reduce the short-term mortality of patients, but could not shorten the ICU length of stay and mechanical ventilation time. More clinical randomized controlled trials are needed to verify the efficacy and safety of dexmedetomidine on the length of hospital stay and mechanical ventilation time.

Effects of dexmedetomidine on delirium and mortality during sedation in ICU patients: a systematic review and meta-analysis protocol

INTRODUCTION

Delirium is very common in patients admitted to intensive care unit (ICU), and may worsen survival in these patients. Several meta-analyses have evaluated the antidelirium effects of dexmedetomidine in ICU patients, but their findings were inconsistent. Recently, several large multicentre randomised clinical trials (RCTs) were published, but they have not yet to be included in any meta-analysis. We will conduct a meta-analysis adding these data to evaluate the effects of dexmedetomidine on delirium and mortality in ICU patients, aiming to terminate controversy and provide robust evidence for guiding clinical practice.

METHODS AND ANALYSIS

The Cochrane Central Register of Controlled Trials, PubMed, Embase, ISI Web of Science will be searched from inception to 31 December 2018 for relevant RCTs. Two reviewers will independently screen the identified citations. After quality appraisal and data extraction of included studies, we will conduct meta-analyses for outcomes of interest, including delirium, mortality, length of ICU/hospital stay, time to extubation, ICU costs and adverse effects. The statistical heterogeneity among studies will be assessed by the χ² test and quantified by the I² statistics. We will undertake subgroup analyses to explore heterogeneity and sensitivity analyses to evaluate whether the results are robust. Potential publication bias will be assessed by funnel plot and Egger's test. At last, the quality of evidence of the main outcomes will be rated using the Grading of Recommendations Assessment, Development and Evaluation system.

ETHICS AND DISSEMINATION

The present study is a meta-analysis based on published studies, thus ethical approval is not needed. Our review will elucidate whether dexmedetomidine could decrease the incidence of delirium and improve survival in ICU patients. Our findings may help clinicians to choose optimal sedative agents for ICU patients. The results of this meta-analysis will be submitted to a peer reviewed journal for publication.

PROSPERO REGISTRATION NUMBER

CRD42018095358.

Sedative drugs used for mechanically ventilated patients in intensive care units: a systematic review and network meta-analysis

BACKGROUND

The effects of different sedative drugs on all-cause mortality rate, duration of ICU stay, and risk of delirium in mechanically ventilated ICU patients are unclear. This meta-analysis aimed to compare the effectiveness and safety of individual sedative drugs and drug combinations in mechanically ventilated ICU patients.

MATERIALS AND METHODS

Medline, Embase, Cochrane, EBSCOhost, and ISI Web of Science databases were searched for studies that assessed sedation in ICU mechanically ventilated patients. A Bayesian random-effects model was used to combine the direct comparisons and indirect evidence.

RESULTS

Thirty-one randomized, controlled trials were included, which consisted of 4491 patients who received one of seven sedative drugs or a combination of drugs. There were no significant differences regarding the all-cause mortality rate. Compared to propofol, inhalation anesthetics (hazard ratio [HR] 0.121; 95% credible interval [CrI] -7.58 to 7.62), alpha agonists (HR 2.2; 95% CrI 0.776 to 5.22), propofol with benzodiazepines (HR 0.306; 95% CrI -6.97 to 7.65), ketamine with benzodiazepines (HR 6.57; 95% CrI -6.05 to 19.1) and placebo (HR 2.4; 95% CrI -5.37 to 10.3), benzodiazepines (HR 3.62; 95% CrI 0.834 to 6.2) may increase the duration of ICU stay. Compared to alpha agonists, propofol (HR 2.4; 95% CrI 0.304 to 21.1) and placebo (HR 6.12; 95% CrI 0.745 to 54.6), benzodiazepines (HR 2.59; 95% CrI 1.08 to 7.4) were associated with incremental risks of delirium.

CONCLUSION

Compared to propofol, benzodiazepines may increase the duration of ICU stay. Compared to alpha agonists, benzodiazepines were associated with an increased risk of delirium.

Sedation, Delirium, and Cognitive Function After Critical Illness

Delirium has been consistently identified as a risk factor for critical illness brain injury, but ICU patients are exposed to a multitude of risk factors for delirium and it remains unclear which of these risk factors should be targeted to improve long-term cognitive outcomes. Because exposure to sedating medications-which are frequently used to treat unwanted yet common symptoms during critical illness-is a risk factor for delirium that is directly controlled by clinicians, the relationship between sedation, delirium, and long-term cognition is of great interest to clinicians, researchers, and patients. This review describes theoretic relationships between sedation, delirium, and long-term cognition and reviews the evidence supporting these theoretic relationships.

Integrative Physiology of Pneumonia

Pneumonia is a type of acute lower respiratory infection that is common and severe. The outcome of lower respiratory infection is determined by the degrees to which immunity is protective and inflammation is damaging. Intercellular and interorgan signaling networks coordinate these actions to fight infection and protect the tissue. Cells residing in the lung initiate and steer these responses, with additional immunity effectors recruited from the bloodstream. Responses of extrapulmonary tissues, including the liver, bone marrow, and others, are essential to resistance and resilience. Responses in the lung and extrapulmonary organs can also be counterproductive and drive acute and chronic comorbidities after respiratory infection. This review discusses cell-specific and organ-specific roles in the integrated physiological response to acute lung infection, and the mechanisms by which intercellular and interorgan signaling contribute to host defense and healthy respiratory physiology or to acute lung injury, chronic pulmonary disease, and adverse extrapulmonary sequelae. Pneumonia should no longer be perceived as simply an acute infection of the lung. Pneumonia susceptibility reflects ongoing and poorly understood chronic conditions, and pneumonia results in diverse and often persistent deleterious consequences for multiple physiological systems.

Septic Encephalopathy

PURPOSE OF THE REVIEW

To discuss the diagnostic approach to patients with septic encephalopathy as well as the need for specific neuro-monitoring and the perspectives on future therapeutic approaches in this setting.

RECENT FINDINGS

Most of data-concern experimental studies evaluating the pathophysiology of septic encephalopathy. A combination of neurodegenerative pathways with neurovascular injury is the cornerstone for the development of such complication and the long-term neurological sequelae among survivors. Septic encephalopathy is a common complication in septic patients. Clinical presentation may range from mild confusion and disorientation to convulsions and deep coma. The diagnosis of septic encephalopathy is made difficult by the lack of any specific clinical and non-clinical feature, in particular among sedated patients in whom neurological examination is unreliable. In spite of the high mortality rate associated with this condition, there is no prophylactic or targeted therapy to reduce or minimize brain damage in septic patients and clinical management is limited to the treatment of the underlying infection.

Effects From Continuous Infusions of Dexmedetomidine and Propofol on Hemodynamic Stability in Critically Ill Adult Patients With Septic Shock

PURPOSE

To compare the development of clinically significant hemodynamic event (ie, hypotension or bradycardia) in adults with septic shock receiving either propofol or dexmedetomidine.

MATERIALS AND METHODS

A retrospective cohort study of adults with septic shock admitted to an intensive care unit (ICU) at an academic medical center between July 2013 and July 2017.

RESULTS

Patients in the propofol (n = 35) and dexmedetomidine (n = 37) groups developed a clinically significant hemodynamic event at similar frequencies (31.4 vs 29.7%, P = .99). All patients with an event experienced hypotension, whereas 2 (5.4%) patients in the dexmedetomidine group also experienced bradycardia. Most patients in both groups (70% vs 90%) received an escalating sedative dose, and almost half (42.9%) in the dexmedetomidine group had the sedative dosage increased more frequently than every 30 minutes. Patients in both groups had similar ICU (24.1 vs 24.3 days, P = .98) and hospital (37.9 vs 29.7 days, P = .29) lengths of stay. There was no difference in median time to hemodynamic event between the groups (propofol 1 hour [interquartile range, IQR: 0.5-9.9] vs dexmedetomidine 2 hours [IQR: 1.5-11.1 hours], P = .85).

CONCLUSION

Patients with septic shock receiving propofol or dexmedetomidine experienced similar rates of clinically significant hemodynamic events. Most patients did not experience an event and those who did most frequently did so in the first couple of hours of therapy.

Evaluating the use of dexmedetomidine for the reduction of delirium: An integrative review

Delirium, an acute change in cognition and attention not secondary to a pre-existing condition or dementia, affects nearly 40,000 hospitalized older adults in the United States every day. Delirium is associated with increased healthcare costs of $16,303 to $64,421 per patient. To date, no single pharmacological intervention is effective in preventing or treating delirium in critically ill patients. Evidence suggests the alpha-2 agonist, dexmedetomidine, may reduce or prevent delirium. An integrative review examined whether dexmedetomidine was associated with a lower incidence of delirium compared to other analgesic and sedation strategies. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guided this review and 16 publications met quality criteria for inclusion. These studies support that postoperative administration of dexmedetomidine may reduce delirium in patients, particularly following cardiac surgery. Further research is needed to determine the benefits of dexmedetomidine in patients on mechanical ventilation and optimal timing and duration of administration.

Mismatch negativity to predict subsequent awakening in deeply sedated critically ill patients

BACKGROUND

Mismatch negativity (MMN) is the neurophysiological correlate of cognitive integration of novel stimuli. Although MMN is a well-established predictor of awakening in non-sedated comatose patients, its prognostic value in deeply sedated critically ill patients remains unknown. The aim of this prospective, observational pilot study was to investigate the prognostic value of MMN for subsequent awakening in deeply sedated critically ill patients.

METHODS

MMN was recorded in 43 deeply sedated critically ill patients on Day 3 of ICU admission using a classical 'odd-ball' paradigm that delivers rare deviant sounds in a train of frequent standard sounds. Individual visual analyses and a group level analysis of recordings were performed. MMN amplitudes were then analysed according to the neurological status (awake vs not awake) at Day 28.

RESULTS

Median (inter-quartile range) Richmond Assessment Sedation Scale (RASS) at the time of recording was -5 (range, from -5 to -4.5). Visual detection of MMN revealed a poor inter-rater agreement [kappa=0.17, 95% confidence interval (0.07-0.26)]. On Day 28, 30 (70%) patients had regained consciousness while 13 (30%) had not. Quantitative group level analysis revealed a significantly greater MMN amplitude for patients who awakened compared with those who had not [mean (standard deviation) = -0.65 (1.4) vs 0.08 (0.17) μV, respectively; P=0.003).

CONCLUSIONS

MMN can be observed in deeply sedated critically ill patients and could help predict subsequent awakening. However, visual analysis alone is unreliable and should be systematically completed with individual level statistics.