Alpha-2 agonists for sedation of mechanically ventilated adults in intensive care units: a systematic review

Weaning-associated interventions for ventilated intensive care patients: A scoping review

BACKGROUND

Mechanical ventilation is a core intervention in critical care, but may also lead to negative consequences. Therefore, ventilator weaning is crucial for patient recovery. Numerous weaning interventions have been investigated, but an overview of interventions to evaluate different foci on weaning research is still missing.

AIM

To provide an overview of interventions associated with ventilator weaning.

STUDY DESIGN

We conducted a scoping review. A systematic search of the Medline, CINAHL and Cochrane Library databases was carried out in May 2023. Interventions from studies or reviews that aimed to extubate or decannulate mechanically ventilated patients in intensive care units were included. Studies concerning children, outpatients or non-invasive ventilation were excluded. Screening and data extraction were conducted independently by three reviewers. Identified interventions were thematically analysed and clustered.

RESULTS

Of the 7175 records identified, 193 studies were included. A total of six clusters were formed: entitled enteral nutrition (three studies), tracheostomy (17 studies), physical treatment (13 studies), ventilation modes and settings (47 studies), intervention bundles (42 studies), and pharmacological interventions including analgesic agents (8 studies), sedative agents (53 studies) and other agents (15 studies).

CONCLUSIONS

Ventilator weaning is widely researched with a special focus on ventilation modes and pharmacological agents. Some aspects remain poorly researched or unaddressed (e.g. nutrition, delirium treatment, sleep promotion).

RELEVANCE TO CLINICAL PRACTICE

This review compiles studies on ventilator weaning interventions in thematic clusters, highlighting the need for multidisciplinary care and consideration of various interventions. Future research should combine different interventions and investigate their interconnection.

Using the sympathetic system, beta blockers and alpha-2 agonists, to address acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) manifests as an acute inflammatory lung injury characterized by persistent hypoxemia, featuring a swift onset, high mortality, and predominantly supportive care as the current therapeutic approach, while effective treatments remain an area of active investigation. Adrenergic receptors (AR) play a pivotal role as stress hormone receptors, extensively participating in various inflammatory processes by initiating downstream signaling pathways. Advancements in molecular biology and pharmacology continually unveil the physiological significance of distinct AR subtypes. Interventions targeting these subtypes have the potential to induce specific alterations in cellular and organismal functions, presenting a promising avenue as a therapeutic target for managing ARDS. This article elucidates the pathogenesis of ARDS and the basic structure and function of AR. It also explores the relationship between AR and ARDS from the perspective of different AR subtypes, aiming to provide new insights for the improvement of ARDS.

A Comparative Study of the Antiemetic Effects of α2-Adrenergic Receptor Agonists Clonidine and Dexmedetomidine against Diverse Emetogens in the Least Shrew (Cryptotis parva) Model of Emesis

In contrast to cats and dogs, here we report that the α2-adrenergic receptor antagonist yohimbine is emetic and corresponding agonists clonidine and dexmedetomidine behave as antiemetics in the least shrew model of vomiting. Yohimbine (0, 0.5, 0.75, 1, 1.5, 2, and 3 mg/kg, i.p.) caused vomiting in shrews in a bell-shaped and dose-dependent manner, with a maximum frequency (0.85 ± 0.22) at 1 mg/kg, which was accompanied by a key central contribution as indicated by increased expression of c-fos, serotonin and substance P release in the shrew brainstem emetic nuclei. Our comparative study in shrews demonstrates that clonidine (0, 0.1, 1, 5, and 10 mg/kg, i.p.) and dexmedetomidine (0, 0.01, 0.05, and 0.1 mg/kg, i.p.) not only suppress yohimbine (1 mg/kg, i.p.)-evoked vomiting in a dose-dependent manner, but also display broad-spectrum antiemetic effects against diverse well-known emetogens, including 2-Methyl-5-HT, GR73632, McN-A-343, quinpirole, FPL64176, SR141716A, thapsigargin, rolipram, and ZD7288. The antiemetic inhibitory ID50 values of dexmedetomidine against the evoked emetogens are much lower than those of clonidine. At its antiemetic doses, clonidine decreased shrews' locomotor activity parameters (distance moved and rearing), whereas dexmedetomidine did not do so. The results suggest that dexmedetomidine represents a better candidate for antiemetic potential with advantages over clonidine.

Conformationally Selective 2-Aminotetralin Ligands Targeting the alpha2A- and alpha2C-Adrenergic Receptors

Many important physiological processes are mediated by alpha2A- and alpha2C-adrenergic receptors (α2Rs), a subtype of class A G protein-coupled receptors (GPCRs). However, α2R signaling is poorly understood, and there are few approved medications targeting these receptors. Drug discovery aimed at α2Rs is complicated by the high degree of binding pocket homology between α2AR and α2CR, which confounds ligand-mediated selective activation or inactivation of signaling associated with a particular subtype. Meanwhile, α2R signaling is complex and it is reported that activating α2AR is beneficial in many clinical contexts, while activating α2CR signaling may be detrimental to these positive effects. Here, we report on a novel 5-substituted-2-aminotetralin (5-SAT) chemotype that, depending on substitution, has diverse pharmacological activities at α2Rs. Certain lead 5-SAT analogues act as partial agonists at α2ARs, while functioning as inverse agonists at α2CRs, a novel pharmacological profile. Leads demonstrate high potency (e.g., EC50 < 2 nM) at the α2AR and α2CRs regarding Gαi-mediated inhibition of adenylyl cyclase and production of cyclic adenosine monophosphate (cAMP). To help understand the molecular basis of 5-SAT α2R multifaceted functional activity, α2AR and α2CR molecular models were built from the crystal structures and 1 μs molecular dynamics (MD) simulations and molecular docking experiments were performed for a lead 5-SAT with α2AR agonist and α2CR inverse agonist activity, i.e., (2S)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine (FPT), in comparison to the FDA-approved (for opioid withdrawal symptoms) α2AR/α2CR agonist lofexidine. Results reveal several interactions between FPT and α2AR and α2CR amino acids that may impact the functional activity. The computational data in conjunction with experimental in vitro affinity and function results provide information to understand ligand stabilization of functionally distinct GPCR conformations regarding α2AR and α2CRs.

Postoperative recovery among head and neck cancer patients receiving microvascular free flap surgery with implementing nurse-protocolized targeted sedation: relationship of use of sedatives and mechanical ventilation to length of ICU stay

PURPOSE

Patients receiving microvascular free flap surgery are usually admitted to a high-dependency adult intensive care unit (ICU). Research is limited to investigate postoperative recovery among head and neck cancer patients in the ICU. This study aimed to evaluate a nursing-protocolized targeted sedation on postoperative recovery and to examine the relationship of demographic characteristics, use of sedation, mechanical ventilator to length of ICU stay in patients receiving microvascular free flap surgery for head and neck reconstruction.

METHODS

This retrospective study involves 125 ICU patients at a medical centre in Taiwan. Medical records were reviewed between 1 January 2015 and 31 December 2018 including surgery-related data, medications and sedations used, and ICU-related outcomes.

RESULTS

The mean length of ICU stay was 6.2 days (SD = 2.6), and the mean duration of mechanical ventilation was 4.7 days (SD = 2.3). The daily dosage of sedation used in patients who received microvascular free flap surgery was dramatically reduced since the postoperative day (POD) 7. Over 50% of patients switched to PS + SIMV ventilator mode on POD 4. Duration of sedation used (r = 0.331, p < 0.001), total dosage of sedation (r = 0.901, p < 0.001), clear consciousness (r =  - 0.517, p < 0.001), and duration on mechanical ventilator (r = 0.378, p < 0.001) are correlated with the length of ICU stay.

CONCLUSION

This study provides an understanding of the use of sedation, mechanical ventilator, and length of ICU stay to inform the continued education for clinicians.

Dexmedetomidine in Psychiatry: Repurposing of its Fast-Acting Anxiolytic, Analgesic and Sleep Modulating Properties

Drug repurposing is a strategy to identify new indications for already approved drugs. A recent successful example in psychiatry is ketamine, an anesthetic drug developed in the 1960s, now approved and clinically used as a fast-acting antidepressant. Here, we describe the potential of dexmedetomidine as a psychopharmacological repurposing candidate. This α₂-adrenoceptor agonist is approved in the US and Europe for procedural sedation in intensive care. It has shown fast-acting inhibitory effects on perioperative stress-related pathologies, including psychomotor agitation, hyperalgesia, and neuroinflammatory overdrive, proving potentially useful in clinical psychiatry. We offer an overview of the pharmacological profile and effects of dexmedetomidine with potential utility for the treatment of neuropsychiatric symptoms. Dexmedetomidine exerts fast-acting and robust sedation, anxiolytic, analgesic, sleep-modulating, and anti-inflammatory effects. Moreover, the drug prevents postoperative agitation and delirium, possibly via neuroprotective mechanisms. While evidence in animals and humans supports these properties, larger controlled trials in clinical samples are generally scarce, and systematic studies with psychiatric patients do not exist. In conclusion, dexmedetomidine is a promising candidate for an experimental treatment targeting stress-related pathologies common in neuropsychiatric disorders such as depression, anxiety disorders, and posttraumatic stress disorder. First small proof-of-concept studies and then larger controlled clinical trials are warranted in psychiatric populations to test the feasibility and efficacy of dexmedetomidine in these conditions.

Evaluation of the Relationship between Baseline Autonomic Tone and Haemodynamic Effects of Dexmedetomidine

Dexmedetomidine, a central α-2 agonist, is used for procedural sedation and for conscious sedation influences on heart rate and blood pressure. Authors verified whether it is possible to predict bradycardia and hypotension with the use of heart rate variability (HRV) analysis for an autonomic nervous system (ANS) activity assessment. The study included adult patients of both sexes with an ASA score of I or II scheduled for ophthalmic surgery to be performed under sedation. The loading dose of dexmedetomidine was followed by a 15 min infusion of the maintenance dose. The frequency domain heart rate variability parameters from the 5-min Holter electrocardiogram recordings before dexmedetomidine administration were used for the analysis. The statistical analysis also included pre-drug heart rate and blood pressure as well as patient age and sex. The data from 62 patients were analysed. There was no relationship between the decrease in heart rate (42% of cases) and initial HRV parameters, haemodynamic parameters or sex and age of patients. In multivariate analysis, the only risk factor for a decrease in mean arterial pressure (MAP) > 15% from the pre-drug value (39% of cases) was the systolic blood pressure before dexmedetomidine administration as well as for a >15% decrease in MAP sustained at more than one consecutive time point (27% of cases). The initial condition of the ANS did not correlate with the incidence of bradycardia or hypotension; HRV analysis was not helpful in predicting the abovementioned side effects of dexmedetomidine.

Paediatric sepsis-associated encephalopathy (SAE): a comprehensive review

Sepsis-associated encephalopathy (SAE) is one of the most common types of organ dysfunction without overt central nervous system (CNS) infection. It is associated with higher mortality, low quality of life, and long-term neurological sequelae, its mortality in patients diagnosed with sepsis, progressing to SAE, is 9% to 76%. The pathophysiology of SAE is still unknown, but its mechanisms are well elaborated, including oxidative stress, increased cytokines and proinflammatory factors levels, disturbances in the cerebral circulation, changes in blood-brain barrier permeability, injury to the brain's vascular endothelium, altered levels of neurotransmitters, changes in amino acid levels, dysfunction of cerebral microvascular cells, mitochondria dysfunction, activation of microglia and astrocytes, and neuronal death. The diagnosis of SAE involves excluding direct CNS infection or other types of encephalopathies, which might hinder its early detection and appropriate implementation of management protocols, especially in paediatric patients where only a few cases have been reported in the literature. The most commonly applied diagnostic tools include electroencephalography, neurological imaging, and biomarker detection. SAE treatment mainly focuses on managing underlying conditions and using antibiotics and supportive therapy. In contrast, sedative medication is used judiciously to treat those showing features such as agitation. The most widely used medication is dexmedetomidine which is neuroprotective by inhibiting neuronal apoptosis and reducing a sepsis-associated inflammatory response, resulting in improved short-term mortality and shorter time on a ventilator. Other agents, such as dexamethasone, melatonin, and magnesium, are also being explored in vivo and ex vivo with encouraging results. Managing modifiable factors associated with SAE is crucial in improving generalised neurological outcomes. From those mentioned above, there are still only a few experimentation models of paediatric SAE and its treatment strategies. Extrapolation of adult SAE models is challenging because of the evolving brain and technical complexity of the model being investigated. Here, we reviewed the current understanding of paediatric SAE, its pathophysiological mechanisms, diagnostic methods, therapeutic interventions, and potential emerging neuroprotective agents.

What Is the Role of Dexmedetomidine in Modern Anesthesia and Critical Care?

Dexmedetomidine's unique sedative properties have led to its widespread use. Dexmedetomidine has a beneficial pharmacologic profile including analgesic sparing effects, anxiolysis, sympatholysis, organ-protective effects against ischemic and hypoxic injury, and sedation which parallels natural sleep. An understanding of predictable side effects, effects of age-related physiologic changes, and pharmacokinetic and pharmacodynamic effects of dexmedetomidine is crucial to maximize its safe administration in adults and children. This review focuses on the growing body of literature examining advances in applications of dexmedetomidine in children and adults.

Sleep cycle in children with severe acute bronchopneumonia during mechanical ventilation at different depths of sedation

BACKGROUND

To investigate the characteristics of sleep cycle in children with severe acute bronchopneumonia treated with invasive mechanical ventilation at different sedation depths.

METHODS

We included 35 pediatric patients with severe acute bronchopneumonia treated using mechanical ventilation in Pediatric Intensive Care Unit of Shengjing Hospital of China Medical University. They were divided into deep sedation group (n = 21; ramsay score 5-6) and light sedation group (n = 14; ramsay score3-4) based on sedation depth achieved during mechanical ventilation. Long-term video electroencephalography (EEG) monitoring was performed within the first 24 h after starting mechanical ventilation and after weaning from mechanical ventilation and discontinuing sedatives and analgesics. The results were analyzed and compared with those of normal children to analyze changes in sleep cycle characteristics at different sedation depths and mechanical ventilation stages.

RESULTS

There were 29 cases altered sleep architecture. The deep sedation group had a significantly higher incidence of sleep architecture altered, total sleep duration, and non-rapid eye movement sleep-1 (NREM-1) loss incidence than the light sedation group. Moreover, the deep sedation group had a significantly lower awakening number and rapid eye movement sleep (REM) percentage than the light sedation group. The sleep cycle returned to normal in 27 (77%) patients without NREM-1 or REM sleep loss.

CONCLUSIONS

Deep sedation during mechanical ventilation allows longer total sleep duration, fewer awakenings, and an increased deep sleep proportion, but sleep architecture is severely altered. After weaning from mechanical ventilation and sedative discontinuation, lightly sedated children exhibit better sleep recovery.

Dexmedetomidine Diminishes, but Does Not Prevent, Developmental Effects of Sevoflurane in Neonatal Rats

BACKGROUND

Sevoflurane (SEVO) increases neuronal excitation in neonatal rodent brains through alteration of gamma aminobutyric acid (GABA)(A) receptor signaling and increases corticosterone release. These actions may contribute to mechanisms that initiate the anesthetic's long-term neuroendocrine and neurobehavioral effects. Dexmedetomidine (DEX), a non-GABAergic α2-adrenergic receptor agonist, is likely to counteract SEVO-induced neuronal excitation. We investigated how DEX pretreatment may alter the neurodevelopmental effects induced by SEVO in neonatal rats.

METHODS

Postnatal day (P) 5 Sprague-Dawley male rats received DEX (25 µg/kg, intraperitoneal) or vehicle before exposure to 2.1% SEVO for 6 hours (the DEX + SEVO and SEVO groups, respectively). Rats in the DEX-only group received DEX without exposure to SEVO. A subcohort of P5 rats was used for electroencephalographic and serum corticosterone measurements. The remaining rats were sequentially evaluated in the elevated plus maze on P80, prepulse inhibition of the acoustic startle response on P90, Morris water maze (MWM) starting on P100, and for corticosterone responses to physical restraint for 30 minutes on P120, followed by assessment of epigenomic DNA methylation patterns in the hippocampus.

RESULTS

Acutely, DEX depressed SEVO-induced electroencephalogram-detectable seizure-like activity (mean ± SEM, SEVO versus DEX + SEVO, 33.1 ± 5.3 vs 3.9 ± 5.3 seconds, P < .001), but it exacerbated corticosterone release (SEVO versus DEX + SEVO, 169.935 ± 20.995 versus 280.853 ± 40.963 ng/mL, P = .043). DEX diminished, but did not fully abolish, SEVO-induced corticosterone responses to restraint (control: 11625.230 ± 877.513, SEVO: 19363.555 ± 751.325, DEX + SEVO: 15012.216 ± 901.706, DEX-only: 12497.051 ± 999.816; F[3,31] = 16.878, P < .001) and behavioral deficiencies (time spent in the target quadrant of the MWM: control: 31.283% ± 1.722%, SEVO: 21.888% ± 2.187%, DEX + SEVO: 28.617% ± 1.501%, DEX-only: 31.339% ± 3.087%; F[3,67] = 3.944, P = .012) in adulthood. Of the 391 differentially methylated genes in the SEVO group, 303 genes in the DEX + SEVO group had DNA methylation patterns that were not different from those in the control group (ie, they were normal). DEX alone did not cause acute or long-term functional abnormalities.

CONCLUSIONS

This study suggests that the ability of DEX to depress SEVO-induced neuronal excitation, despite increasing corticosterone release, is sufficient to weaken mechanisms leading to long-term neuroendocrine/neurobehavioral abnormalities. DEX may prevent changes in DNA methylation in the majority of genes affected by SEVO, epigenetic modifications that could predict abnormalities in a wide range of functions.

Minimal alveolar concentration of sevoflurane in combination with dexmedetomidine in patients with hysteroscopy: An up-down sequential allocation study

BACKGROUND

Dexmedetomidine is commonly used in hysteroscopy surgery due to its analgesia and sedation without respiratory depression. Many studies have shown that dexmedetomidine can reduce the consumption of sevoflurane. However, the optimal end-tidal concentration of sevoflurane when it is co-administered with dexmedetomidine has not been established. The primary purpose of this study was to investigate the minimal alveolar concentration (MAC) of sevoflurane for cervical dilatation combined with different doses of dexmedetomidine in patients with hysteroscopy surgery.

METHODS

One-hundred patients undergoing hysteroscopy surgery were enrolled in this clinical trial. All the patients were randomly assigned into four groups (C, D₁ , D₂ , D₃ ) and received a loading dose of dexmedetomidine (0, 0.6, 0.8 and 1.0 μg/kg) over 10 min before anaesthesia induction, respectively. Anaesthesia was induced in each patient with 5% sevoflurane in 100% oxygen via a facemask. A laryngeal mask (LMA) was inserted when the patient had lost consciousness and the BIS value decreased below 40. The response to cervical dilatation stimulus (movement vs non-movement) by the insert of hysteroscope was recorded. The MAC of sevoflurane was measured by up and down sequential method of Dixon and Mood and centred isotonic regression analysis.

RESULTS

The calculated MAC of sevoflurane using up-and-down method of Dixon and Mood in patients with hysteroscopy surgery was (1.90 ± 0.13)%, (1.23 ± 0.16)%, (1.03 ± 0.10)% and (0.93 ± 0.08)% in groups C, D₁ , D₂ and D₃ , respectively.

CONCLUSIONS

The administration of dexmedetomidine can significantly decrease the MAC of sevoflurane for hysteroscopy surgery. However, a ceiling effect of the reduction was observed when the dose of dexmedetomidine was higher than 0.8 μg/kg.

Effects of Dexmedetomidine on Immune Cells: A Narrative Review

As we all know, dexmedetomidine (DEX), as a highly selective α₂ adrenergic receptor agonist, exerts sedative, anti-anxiety and hypnotic effects by inhibiting the discharge of norepinephrine neurons in locus coeruleus and GABA-related hypnotic pathways. However, the role of DEX in anti-inflammatory and immune regulation has gradually attracted the attention of researchers in recent years. The α₂ adrenergic receptor is one of the members of the adrenergic receptor family, which is widely present in a variety of immune cells and mediates the biological behavior of the inflammatory immune system. At present, there have been more and more studies on the effects of DEX on immune cells and inflammatory responses, but few studies have systematically explored the anti-inflammatory and immunomodulatory effects of DEX. Here, we comprehensively review the published human and animal studies related to DEX, summarize the effects of DEX on immune cells and its role in related diseases, and propose potential research direction.

High sedation needs of critically ill COVID-19 ARDS patients-A monocentric observational study

BACKGROUND

Therapy of severely affected coronavirus patient, requiring intubation and sedation is still challenging. Recently, difficulties in sedating these patients have been discussed. This study aims to describe sedation practices in patients with 2019 coronavirus disease (COVID-19)-induced acute respiratory distress syndrome (ARDS).

METHODS

We performed a retrospective monocentric analysis of sedation regimens in critically ill intubated patients with respiratory failure who required sedation in our mixed 32-bed university intensive care unit. All mechanically ventilated adults with COVID-19-induced ARDS requiring continuously infused sedative therapy admitted between April 4, 2020, and June 30, 2020 were included. We recorded demographic data, sedative dosages, prone positioning, sedation levels and duration. Descriptive data analysis was performed; for additional analysis, a logistic regression with mixed effect was used.

RESULTS

In total, 56 patients (mean age 67 (±14) years) were included. The mean observed sedation period was 224 (±139) hours. To achieve the prescribed sedation level, we observed the need for two or three sedatives in 48.7% and 12.8% of the cases, respectively. In cases with a triple sedation regimen, the combination of clonidine, esketamine and midazolam was observed in most cases (75.7%). Analgesia was achieved using sufentanil in 98.6% of the cases. The analysis showed that the majority of COVID-19 patients required an unusually high sedation dose compared to those available in the literature.

CONCLUSION

The global pandemic continues to affect patients severely requiring ventilation and sedation, but optimal sedation strategies are still lacking. The findings of our observation suggest unusual high dosages of sedatives in mechanically ventilated patients with COVID-19. Prescribed sedation levels appear to be achievable only with several combinations of sedatives in most critically ill patients suffering from COVID-19-induced ARDS and a potential association to the often required sophisticated critical care including prone positioning and ECMO treatment seems conceivable.

Sedation in the Intensive Care Unit

PURPOSE OF REVIEW

This narrative review illustrates literature over the last 5 years relating to sedation delivery to mechanically ventilated adult patients in intensive care units.

RECENT FINDINGS

There has been an increase in dexmedetomidine-related publications but although systematic reviews suggest dexmedetomidine reduces delirium, agitation, and length of stay, clinical trials have not supported these findings. It is likely to be useful for the managing patients with persisting agitation. Guidelines continue to recommend lightly sedating patients but considerable variation remains in clinical practice and in research trials. Protocols with no sedative infusions and morphine boluses as needed are feasible and safe, while educational interventions can decrease sedation-related adverse events.

SUMMARY

Research trials have mainly focused on individual drugs rather than practice. Given evidence is slow to translate into practice; work is needed to understand and respond to the concerns of clinicians regarding deep sedation and agitation.

Effect of age on dexmedetomidine treatment for ventilated patients with sepsis: a post-hoc analysis of the DESIRE trial

Aim

There are no definitive data to determine whether age influences the effects of dexmedetomidine (DEX) treatment. Thus, we investigated whether older age was associated with more favorable sedative action by DEX in sepsis patients who required mechanical ventilation.

Methods

This study involved a post‐hoc analysis of data from the Dexmedetomidine for Sepsis in the ICU Randomized Evaluation (DESIRE) trial. The patients were categorized based on median age into elderly and younger groups. The two groups were then compared during the first 7 days after ventilation based on proportion of patients with well‐controlled sedation (Richmond Agitation–Sedation Scale score between −3 and +1), days free from delirium (based on the Confusion Assessment Method for ICU), and days free from coma (Richmond Agitation–Sedation Scale score between −4 and −5).

Results

One hundred and one patients were assigned to the elderly group and 100 patients were assigned to the younger group. In the elderly group, 50 patients received DEX treatment and 51 patients received non‐DEX treatment, with the DEX arm having significantly better‐controlled sedation (range, 14–52% versus 16–27%; P = 0.01). In the younger group, 50 patients received DEX treatment and 50 patients received non‐DEX treatment, with no significant difference in the proportions of well‐controlled sedation (range, 20–64% versus 24–60%; P = 0.73). There were no significant differences in the numbers of days free from delirium or coma between the groups.

Conclusion

In elderly sepsis patients who require ventilation, dexmedetomidine could be more effective than other sedative agents for achieving proper sedation.

Consensus for the management of analgesia, sedation and delirium in adults with COVID-19-associated acute respiratory distress syndrome

OBJECTIVE

To propose agile strategies for a comprehensive approach to analgesia, sedation, delirium, early mobility and family engagement for patients with COVID-19-associated acute respiratory distress syndrome, considering the high risk of infection among health workers, the humanitarian treatment that we must provide to patients and the inclusion of patients' families, in a context lacking specific therapeutic strategies against the virus globally available to date and a potential lack of health resources.

METHODS

A nonsystematic review of the scientific evidence in the main bibliographic databases was carried out, together with national and international clinical experience and judgment. Finally, a consensus of recommendations was made among the members of the Committee for Analgesia, Sedation and Delirium of the Sociedad Argentina de Terapia Intensiva.

RESULTS

Recommendations were agreed upon, and tools were developed to ensure a comprehensive approach to analgesia, sedation, delirium, early mobility and family engagement for adult patients with acute respiratory distress syndrome due to COVID-19.

DISCUSSION

Given the new order generated in intensive therapies due to the advancing COVID-19 pandemic, we propose to not leave aside the usual good practices but to adapt them to the particular context generated. Our consensus is supported by scientific evidence and national and international experience and will be an attractive consultation tool in intensive therapies.

Dexmedetomidine reduces ventilator-induced lung injury via ERK1/2 pathway activation

Mechanical ventilation (MV) can contribute to ventilator-induced lung injury (VILI); dexmedetomidine (Dex) treatment attenuates MV-related pulmonary inflammation, but the mechanisms remain unclear. Therefore, the present study aimed to explore the protective effect and the possible molecular mechanisms of Dex in a VILI rodent model. Adult male Sprague-Dawley rats were randomly assigned to one of seven groups (n=24 rats/group). Rats were euthanized after 4 h of continuous MV, and pathological changes, lung wet/dry (W/D) weight ratio, the levels of inflammatory cytokines (IL-1β, TNF-α and IL-6) in the bronchoalveolar lavage fluid (BALF), and the expression levels of Bcl-2 homologous antagonist/killer (Bak), Bcl-2, pro-caspase-3, cleaved caspase-3 and the phosphorylation of ERK1/2 in the lung tissues were measured. Propidium iodide uptake and TUNEL staining were used to detect epithelial cell death. The Dex pretreatment group exhibited fewer pathological changes, lower W/D ratios and lower expression levels of inflammatory cytokines in BALF compared with the VILI group. Dex significantly attenuated the ratio of Bak/Bcl-2, cleaved caspase-3 expression levels and epithelial cell death, and increased the expression of phosphorylated ERK1/2. The protective effects of Dex could be partially reversed by PD98059, which is a mitogen-activated protein kinase (upstream of ERK1/2) inhibitor. Overall, dexmedetomidine was found to reduce the inflammatory response and epithelial cell death caused by VILI, via the activation of the ERK1/2 signaling pathway.

Effects of Anesthesia on Postoperative Recurrence and Metastasis of Malignant Tumors

It is difficult to control the recurrence and metastasis of malignant tumors; furthermore, anesthesia is considered one of the main influencing factors. There has been increasing clinical attention on the effects of anesthetic drugs and methods on postoperative tumor growth and metastasis. We reviewed the effects of anesthesia on tumor recurrence and metastasis; specifically, the effects of anesthetic agents, anesthesia methods, and related factors during the perioperative period on the tumor growth and metastasis were analyzed. This study can provide reference standards for rational anesthesia formulations and cancer-related pain analgesia protocols for surgical procedures in patients with malignant tumors. Moreover, it contributes toward an experimental basis for the improvement and development of novel anesthetic agents and methods.

<p>Cost-Minimization Analysis of Dexmedetomidine Compared to Other Sedatives for Short-Term Sedation During Mechanical Ventilation in the United States</p>

Purpose

Mechanical ventilation (MV) remains a substantial cost driver in intensive care units (ICU) in the United States (US). Evaluations of standard sedation treatments used to relieve pain and discomfort in this setting have found varying impacts on ICU length of stay. This cost analysis examines both length-of=stay costs and the total cost implications among MV patients receiving common sedative treatments (dexmedetomidine, propofol, or midazolam) in short-term sedation settings (<24 hours).

Methods

A cost-minimization model was conducted from the hospital provider perspective. Clinical outcomes were obtained from published literature and included ICU length of stay, MV duration, prescription of sedatives and pain medication, and the occurrence of adverse events. Outcomes costs were obtained from previously conducted ICU cost studies and Medicare payment fee schedules. All costs were estimated in 2018 US Dollars.

Results

The per patient costs associated with dexmedetomidine, propofol, and midazolam were estimated to be $21,115, $27,073, and $27,603, respectively. Dexmedetomidine was associated with a savings of $5958 per patient compared to propofol and a saving of $6487 compared to midazolam. These savings were primarily driven by a reduction in ICU length of stay and the degree of monitoring and management.

Conclusion

Dexmedetomidine was associated with reduced costs when compared to propofol or midazolam used for short-term sedation during MV in the ICU, suggesting sedative choice can have a potential impact on overall cost per episode.

Cardiovascular Safety of Clonidine and Dexmedetomidine in Critically Ill Patients after Cardiac Surgery

Purpose

The aim of this retrospective study was to assess the haemodynamic adverse effects of clonidine and dexmedetomidine in critically ill patients after cardiac surgery.

Methods

2769 patients were screened during the 30-month study period. Heart rate (HR), mean arterial pressure (MAP), and norepinephrine requirements were assessed 3-hourly during the first 12 hours of the continuous drug infusion. Results are given as median (interquartile range) or numbers (percentages).

Results

Patients receiving clonidine (n = 193) were younger (66 (57-73) vs 70 (63-77) years, p=0.003) and had a lower SAPS II (35 (27-48) vs 41 (31-54), p=0.008) compared with patients receiving dexmedetomidine (n = 141). At the start of the drug infusion, HR (90 (75-100) vs 90 (80-105) bpm, p=0.028), MAP (70 (65-80) vs 70 (65-75) mmHg, p=0.093), and norepinephrine (0.05 (0.00-0.11) vs 0.12 (0.03-0.19) mcg/kg/min, p < 0.001) were recorded in patients with clonidine and dexmedetomidine. Bradycardia (HR < 60 bpm) developed in 7.8% with clonidine and 5.7% with dexmedetomidine (p=0.51). Between baseline and 12 hours, norepinephrine remained stable in the clonidine group (0.00 (-0.04-0.02) mcg/kg/min) and decreased in the dexmedetomidine group (-0.03 (-0.10-0.02) mcg/kg/min, p=0.007).

Conclusions

Dexmedetomidine and the low-cost drug clonidine can both be used safely in selected patients after cardiac surgery.

Mechanisms of Dexmedetomidine in Neuropathic Pain

Dexmedetomidin is a new-generation, highly selective α2 adrenergic receptor agonist with a large number of advantages, including its sedative and analgesic properties, its ability to inhibit sympathetic nerves, its reduced anesthetic dosage, its hemodynamic stability, its mild respiratory depression abilities, and its ability to improve postoperative recognition. Its safety and effectiveness, as well as its ability to provide a certain degree of comfort to patients, make it a useful anesthetic adjuvant for a wide range of clinical applications. For example, dexmedetomidine is commonly used in patients undergoing general anesthesia, and it also exerts sedative effects during tracheal intubation or mechanical ventilation in intensive care unit patients. In recent years, with the deepening of clinical research on dexmedetomidine, the drug is still applied in the treatment of spastic pain, myofascial pain, neuropathic pain, complex pain syndrome, and chronic headache, as well as for multimodal analgesia. However, we must note that the appropriateness of patient and dose selection should be given attention when using this drug; furthermore, patients should be observed for adverse reactions such as hypotension and bradycardia. Therefore, the safety and effectiveness of this drug for long-term use remain to be studied. In addition, basic experimental studies have also found that dexmedetomidine can protect important organs, such as the brain, heart, kidney, liver, and lung, through various mechanisms, such as antisympathetic effects, the inhibition of apoptosis and oxidative stress, and a reduction in the inflammatory response. Moreover, the neuroprotective properties of dexmedetomidine have received the most attention from scholars. Hence, in this review, we mainly focus on the characteristics and clinical applications of dexmedetomidine, especially the role of dexmedetomidine in the nervous system and the use of dexmedetomidine in the relief of neuropathic pain.

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.

Fentanyl vs fentanyl-dexmedetomidine in lumbar foraminotomy surgery

Aim

Lumbar foraminotomy surgery requires a potent opioid with short duration and rapid onset of action. In the present study we intended to compare the efficacy of fentanyl alone vs the combination of dexmedetomidine and fentanyl during lumbar foraminotomy surgery.

Methods

The duration and requirements for first postoperative analgesics, hemodynamic stability, and respective side effects were studied. A prospective, randomized, double blind study of 40 patients (fentanyl group [Fen group] and fentanyl-dexmedetomidine group [Fen-Dex group], n=20 each) scheduled for lumbar foraminotomy surgery under pharmaceutical care intervention was carried out. Patients were classified as class I or II, according to the American Society of Anesthesiologists physical status classification. Patients received intraoperative propofol, sevoflurane, atracurium, and either fentanyl loading dose of 1.0 μg/kg and maintenance infusion dose of 0.2 μg/kg/h in both groups. The patients of the Fen group received normal saline (0.9%) placebo, while the patients of the Fen-Dex group received dexmedetomidine infusion (0.5 μg/kg/h) along with the fentanyl infusion. Postoperative morphine doses were given. Hemodynamic stability, pain, postoperative analgesia requirement, side effects of drugs, and other effects were monitored.

Results

In the Fen-Dex group, the pain score was significantly less than in the Fen group (p<0.05). The time to first postoperative analgesia request was prolonged in the Fen-Dex group compared to the Fen group. On the other hand, requirement of morphine, and postoperative symptoms and episodes of nausea and vomiting were significantly greater in the Fen group than in the Fen-Dex group (p<0.05).

Conclusion

The present study suggests the addition of dexmedetomidine during lumbar foraminotomy surgery at different levels would be beneficial to reduce morphine consumption and any adverse drug reaction.

Psychogenic stress in hospitalized veterinary patients: Causation, implications, and therapies

OBJECTIVE

To review the sources, adverse effects, diagnosis, treatment, and prevention of psychogenic stress in hospitalized human and veterinary patients.

DATA SOURCES

Data were collected by searching PubMed for veterinary and human literature from the past 10 years.

HUMAN DATA SYNTHESIS

Psychogenic stress has been linked to immune suppression; gastrointestinal, cardiovascular, and cutaneous diseases; delayed wound healing; alterations in pain perception; and neurologic impairment. Sources of psychogenic stress include environmental alterations such as excessive noise and light, social and physical factors, sleep disruption, drugs, and underlying disease. Nonpharmacologic options for stress reduction include environmental and treatment modifications, music therapy, and early mobilization. Pharmacologic options include sedation with benzodiazepines and dexmedetomidine. Trazodone and melatonin have been examined for use in sleep promotion but are not currently recommended as standard treatments in ICU.

VETERINARY DATA SYNTHESIS

Activation of the stress response in veterinary patients is largely the same as in people, as are the affected body systems. Possible sources of stress can include social, physical, and environmental factors. No gold standard currently exists for the identification and quantification of stress. A combination of physical examination findings and the results of serum biochemistry, CBC, and biomarker testing can be used to support the diagnosis. Stress scales can be implemented to identify stressed patients and assess severity. Nonpharmacologic treatment options include low-stress handling, pheromones, environmental modifications, and sleep promotion. Pharmacologic options include trazodone, benzodiazepines, dexmedetomidine, and melatonin.

CONCLUSION

The prevalence and clinical significance of psychogenic stress in hospitalized veterinary patients is unknown. Future studies are needed to specifically examine the causative factors of psychogenic stress and the effects of various therapies on stress reduction. The recognition and reduction of psychogenic stress in veterinary patients can lead to improvements in patient care and welfare.

Safety and Efficacy of Ketamine Versus Ketamine-Fentanyl-Dexmedetomidine Combination for Anesthesia and Analgesia in Rats

Ketamine (KET), a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, is most frequently used as an anesthetic, analgesic, and sedative drug in pediatric clinical practices. However, the adverse effects of KET administration such as psychotic episodes limited the use of KET. The aim of the present study was to evaluate whether the addition of small doses of fentanyl (FENT) and dexmedetomidine would reduce the overall KET consumption without concession on the safety and efficacy of anesthesia and analgesia in rats. We compared the effects of KET (50 mg/kg) administration alone and KET (25 mg/kg) combined with FENT (0.005 mg/kg) and dexmedetomidine (0.05 mg/kg) (KFD) on the times of onset and duration of anesthesia and analgesia. Compared with the KET group, the KFD group provides similar onset time of anesthesia, but longer duration of anesthesia, and better analgesic effect. Unlike the KET group, the KFD group had a lower heart rate and higher respiratory rate. Meanwhile, KFD induced markedly changes in the electroencephalography (EEG) spectral power when compared with control and KET. Furthermore, combination of FENT and dexmedetomidine alleviated the liver toxicity of KET. These results indicated that, when compared with KET alone, the administration of KFD combination offered safer and more efficient anesthesia.

A Comparative Study of Midazolam Alone or in Combination with Dexmedetomidine or Clonidine for Awake Fiberoptic Intubation

Background:

Awake fiberoptic intubation (AFOI) is the gold standard technique for managing patients with anticipated difficult airway. Conscious sedation is desirable, not only to make the procedure more tolerable and comfortable for the patient but also to ensure optimal intubating conditions. Ideal sedation regime for AFOI should provide comfort, cooperation, hemodynamic stability, and amnesia along with maintenance of spontaneous respiration. Several sedative agents have been assessed over the past two decades for this purpose but α2 agonists appear to be the favorable choice owing to its sedative, analgesic, amnestic, and sympatholytic properties along with good hemodynamic profile.

Aims:

The present study has been aimed to recognize the characteristics of dexmedetomidine, clonidine, and midazolam and to compare their efficacy in providing optimal intubating conditions as well as hemodynamic stability during AFOI.

Settings and Design:

A prospective double-blind randomized study done in tertiary care hospital.

Materials and Methods:

Sixty patients of American Society of Anesthesiologists physical status Classes I and II aged 18–60 years with anticipated difficult airway were randomly allocated into three groups. All the patients received injection midazolam bolus followed by sedation infusion of midazolam, dexmedetomidine, and clonidine according to the allocated group. Primary outcome includes the time to achieve Ramsay Sedation Score (RSS) ≥2, time taken in intubation, intubation score, comfort score for fiberoptic insertion and intubation, and patient tolerance after intubation. The secondary outcome was hemodynamic, and respiratory variables include changes in heart rate (HR), mean arterial pressure (MAP), oxygen saturation (SpO₂), and respiratory rate during the procedure.

Statistical Analysis:

All data were recorded, summarized, tabulated, and statistically analyzed using SPSS 16.0 version (Chicago, Inc., USA). The data were presented in mean ± standard deviation. P < 0.05 was considered as statistically significant.

Results:

All the three groups were comparable in terms of demographic profile. Time to achieve RSS ≥2 and mean intubation time was significantly less in Groups D and C as compared to Group M (P < 0.001). Among groups, Group D took least time to achieve RSS ≥2 (5.53 ± 0.74) and mean intubation time (4.53 ± 0.91). Similarly, overall intubation score, comfort, and patient tolerance score were significantly more in Group M as compared to Groups D and C (P < 0.001). Among the groups, Group D achieved least intubation score (3.80 ± 0.67) and comfort score (2.53 ± 0.74). Although Groups D and C have a lower mean HR and MAP during the procedure and intubation compared to Group M, the incidence of SpO₂ is most frequent with clonidine.

Conclusions:

Patients who received α2 agonist were calmer and cooperative with less pain and discomfort than the patients who received midazolam. Dexmedetomidine allows better endurance, stable hemodynamics, and patent airway as compared to clonidine.

Dexmedetomidine reduces ventilator-induced lung injury (VILI) by inhibiting Toll-like receptor 4 (TLR4)/nuclear factor (NF)-κB signaling pathway

Mechanical ventilation (MV) may lead to ventilator-induced lung injury (VILI). Previous research has shown that dexmedetomidine attenuates pulmonary inflammation caused by MV, but the underlying mechanisms remain unclear. Our study aims to test whether dexmedetomidine has a protective effect against VILI and to explore the possible molecular mechanisms using the rat model. Thirty adult male Wistar rats weighing 200-250 g were randomly assigned to 5 groups (n = 6): control, low tidal volume MV (LMV), high tidal volume (HVT) MV (HMV), HVT MV + dexmedetomidine (DEX), HVT MV + dexmedetomidine + yohimbine (DEX+Y). Rats were euthanized after being ventilated for 4 hours. Pathological changes, lung wet/dry (W/D) weight ratio, lung myeloperoxidase (MPO) activity, levels of inflammatory cytokines (i.e., interleukin [IL]-1β, tumor necrosis factor alpha [TNF-α], and IL-6) in the bronchoalveolar lavage fluid (BALF) and lung tissues, expression of Toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB, and activation of NF-κB in lung tissues were measured. Compared with HMV, DEX group showed fewer pathological changes, lower W/D ratios and decreased MPO activity of the lung tissues and lower concentrations of the inflammatory cytokines in the BALF and lung tissues. Dexmedetomidine significantly inhibited the expression of TLR4 and NF-κB and activation of NF-κB. Yohimbine partly alleviated the effects of dexmedetomidine. Dexmedetomidine reduced the inflammatory response to HVT-MV and had a protective effect against VILI, with the inhibition of the TLR4/NF-κB signaling pathway, at least partly via α2-adrenoceptors.

Sedation After Cardiac Surgery: Is One Drug Better Than Another?

The classic high-dose narcotic-based cardiac anesthetic has been modified to facilitate a fast-track, rapid recovery in the intensive care unit (ICU). Postoperative sedation is consequently now an essential component in recovery of the patient undergoing cardiac surgery. It must facilitate the patient's unawareness of the environment as well as reduce the discomfort and anxiety caused by surgery, intubation, mechanical ventilation, suction, and physiotherapy. Benzodiazepines seem well suited for this role, but propofol, opioids, and dexmedetomidine are among other agents commonly used for sedation in the ICU. However, what is an ideal sedative for this application? When compared with benzodiazepine-based sedation regimens, nonbenzodiazepines have been associated with shorter duration of mechanical ventilation and ICU length of stay. Current sedation guidelines recommend avoiding benzodiazepine use in the ICU. However, there are no recommendations on which alternatives should be used. In postcardiac surgery patients, inotropes and vasoactive medications are often required because of the poor cardiac function. This makes sedation after cardiac surgery unique in comparison with the requirements for most other ICU patient populations. We reviewed the current literature to try to determine if 1 sedative regimen might be better than others; in particular, we compare outcomes of propofol and dexmedetomidine in postoperative sedation in the cardiac surgical ICU.

Comparison of propofol and dexmedetomidine infused overnight to treat hyperactive and mixed ICU delirium: a protocol for the Basel ProDex clinical trial

BACKGROUND/OBJECTIVES

Delirium is a neurobehavioural disturbance that frequently develops particularly in the intensive care unit (ICU) population. It was first described more than half a century ago, where it was already discovered as a state that might come along with serious complications such as prolonged ICU and hospital stay, reduced quality of life and increased mortality. However, in most cases, there is still lack of proof for causal relationship. Its presence frequently remains unrecognised due to suggested predominance of the hypoactive form. Furthermore, in the general ICU population, it has been shown that the duration of delirium is associated with worse long-term cognitive function. Due to the multifactorial origin of delirium, we have several but no incontestable treatment options. Nonetheless, delirium bears a high burden for patient, family members and the medical care team.The Basel ProDex Study targets improvement of hyperactive and mixed delirium therapy in critically ill patients. We will focus on reducing the duration and severity of delirium by implementing dexmedetomidine into the treatment plan. Dexmedetomidine compared with other sedatives shows fewer side effects representing a better risk profile for delirium treatment in general. This could further contribute to higher patient safety.The aim of the BaProDex Trial is to assess the superiority of dexmedetomidine to propofol for treatment of hyperactive and mixed delirium in the ICU. We hypothesise that dexmedetomidine, compared with propofol administered at night, shortens both the duration and severity of delirium.

METHODS/DESIGN

The Basel ProDex Study is an investigator-initiated, one-institutional, two-centre randomised controlled clinical trial for the treatment of delirium with dexmedetomidine versus propofol in 316 critically ill patients suffering from hyperactive and mixed delirium. The primary outcome measure is delirium duration in hours. Secondary outcomes include delirium-free days at day 28, death at day 28, delirium severity, amount of ventilator days, amount of rescue sedation with haloperidol, length of ICU and hospital stay, and pharmaceutical economic analysis of the treatments. Sample size was estimated to be able to show the superiority of dexmedetomidine compared with propofol regarding the duration of delirium in hours. The trial will be externally monitored according to good clinical practice (GCP) requirements. There are no interim analyses planned for this trial.

ETHICS AND DISSEMINATION

This study will be conducted in compliance with the protocol, the current version of the Declaration of Helsinki, the International Conference on Harmonization- Good Clinical Practice (ICH-GCP) or Europäische Norm International Organization for Standardization (ISO EN 14155; as far as applicable) as well as all national legal and regulatory requirements. Only the study team will have access to trial specific data. Anonymisation will be achieved by a unique patient identification code. Trial data will be archived for a minimum of 10 years after study termination. We plan to publish the data in a major peer-reviewed clinical journal.

TRIALS REGISTRATION

ClinicalTrials.gov Identifier: NCT02807467 PROTOCOL VERSION: Clinical Study Protocol Version 2, 16.08.2016.

Alpha-2 Agonists

Alpha-2 adrenergic receptors are spread throughout the central and peripheral nervous system, specifically in the pontine locus coeruleus, medullospinal tracts, rostral ventrolateral medulla, and the dorsal horn of the spinal cord. Alpha-2 agonist agents cause neuromodulation in these centers, leading to sedation, analgesia, vasodilatation, and bradycardia with little effect on the respiratory drive, which accounts for their good safety profile. The 2 major drugs in this group are clonidine and dexmedetomidine. Their clinical applications in anesthesia practice include providing sedation in the intensive care unit or for minor procedures, adjuvant to general and regional anesthesia, analgesia, and as premedicating agents.

Sedation of mechanically ventilated adults in intensive care unit: a network meta-analysis

Sedatives are commonly used for mechanically ventilated patients in intensive care units (ICU). However, a variety of sedatives are available and their efficacy and safety have been compared in numerous trials with inconsistent results. To resolve uncertainties regarding usefulness of these sedatives, we performed a systematic review and network meta-analysis. Randomized controlled trials comparing sedatives in mechanically ventilated ICU patients were included. Graph-theoretical methods were employed for network meta-analysis. A total of 51 citations comprising 52 RCTs were included in our analysis. Dexmedetomidine showed shorter MV duration than lorazepam (mean difference (MD): 68.7; 95% CI: 18.2-119.3 hours), midazolam (MD: 10.2; 95% CI: 7.7-12.7 hours) and propofol (MD: 3.4; 95% CI: 0.9-5.9 hours). Compared with dexmedetomidine, midazolam was associated with significantly increased risk of delirium (OR: 2.47; 95% CI: 1.17-5.19). Our study shows that dexmedetomidine has potential benefits in reducing duration of MV and lowering the risk of delirium.