Oral Dexmedetomidine Promotes Non-rapid Eye Movement Stage 2 Sleep in Humans

Electroencephalographic insights into the pathophysiological mechanisms of emergence delirium in children and corresponding clinical treatment strategies

Emergence delirium is a common postoperative complication in patients undergoing general anesthesia, especially in children. In severe cases, it can cause unnecessary self-harm, affect postoperative recovery, lead to parental dissatisfaction, and increase medical costs. With the widespread use of inhalation anesthetic drugs (such as sevoflurane and desflurane), the incidence of emergence delirium in children is gradually increasing; however, its pathogenesis in children is complex and unclear. Several studies have shown that age, pain, and anesthetic drugs are strongly associated with the occurrence of emergence delirium. Alterations in central neurophysiology are essential intermediate processes in the development of emergence delirium. Compared to adults, the pediatric nervous system is not fully developed; therefore, the pediatric electroencephalogram may vary slightly by age. Moreover, pain and anesthetic drugs can cause changes in the excitability of the central nervous system, resulting in electroencephalographic changes. In this paper, we review the pathogenesis of and prevention strategies for emergence delirium in children from the perspective of brain electrophysiology-especially for commonly used pharmacological treatments-to provide the basis for understanding the development of emergence delirium as well as its prevention and treatment, and to suggest future research direction.

Daytime dexmedetomidine sedation with closed-loop acoustic stimulation alters slow wave sleep homeostasis in healthy adults

Background

The alpha-2 adrenergic agonist dexmedetomidine induces EEG patterns resembling those of non-rapid eye movement (NREM) sleep. Fulfilment of slow wave sleep (SWS) homeostatic needs would address the assumption that dexmedetomidine induces functional biomimetic sleep states.

Methods

In-home sleep EEG recordings were obtained from 13 healthy participants before and after dexmedetomidine sedation. Dexmedetomidine target-controlled infusions and closed-loop acoustic stimulation were implemented to induce and enhance EEG slow waves, respectively. EEG recordings during sedation and sleep were staged using modified American Academy of Sleep Medicine criteria. Slow wave activity (EEG power from 0.5 to 4 Hz) was computed for NREM stage 2 (N2) and NREM stage 3 (N3/SWS) epochs, with the aggregate partitioned into quintiles by time. The first slow wave activity quintile served as a surrogate for slow wave pressure, and the difference between the first and fifth quintiles as a measure of slow wave pressure dissipation.

Results

Compared with pre-sedation sleep, post-sedation sleep showed reduced N3 duration (mean difference of -17.1 min, 95% confidence interval -30.0 to -8.2, P=0.015). Dissipation of slow wave pressure was reduced (P=0.02). Changes in combined durations of N2 and N3 between pre- and post-sedation sleep correlated with total dexmedetomidine dose, (r=-0.61, P=0.03).

Conclusions

Daytime dexmedetomidine sedation and closed-loop acoustic stimulation targeting EEG slow waves reduced N3/SWS duration and measures of slow wave pressure dissipation on the post-sedation night in healthy young adults. Thus, the paired intervention induces sleep-like states that fulfil certain homeostatic NREM sleep needs in healthy young adults.

Clinical trial registration

ClinicalTrials.gov NCT04206059.

Effect of prolonged sedation with dexmedetomidine, midazolam, propofol, and sevoflurane on sleep homeostasis in rats

BACKGROUND

Sleep disruption is a common occurrence during medical care and is detrimental to patient recovery. Long-term sedation in the critical care setting is a modifiable factor that affects sleep, but the impact of different sedative-hypnotics on sleep homeostasis is not clear.

METHODS

We conducted a systematic comparison of the effects of prolonged sedation (8 h) with i.v. and inhalational agents on sleep homeostasis. Adult Sprague-Dawley rats (n=10) received dexmedetomidine or midazolam on separate days. Another group (n=9) received propofol or sevoflurane on separate days. A third group (n=12) received coadministration of dexmedetomidine and sevoflurane. Wakefulness (wake), slow-wave sleep (SWS), and rapid eye movement (REM) sleep were quantified during the 48-h post-sedation period, during which we also assessed wake-associated neural dynamics using two electroencephalographic measures: theta-high gamma phase-amplitude coupling and high gamma weighted phase-lag index.

RESULTS

Dexmedetomidine-, midazolam-, or propofol-induced sedation increased wake and decreased SWS and REM sleep (P<0.0001) during the 48-h post-sedation period. Sevoflurane produced no change in SWS, decreased wake for 3 h, and increased REM sleep for 6 h (P<0.02) post-sedation. Coadministration of dexmedetomidine and sevoflurane induced no change in wake (P>0.05), increased SWS for 3 h, and decreased REM sleep for 9 h (P<0.02) post-sedation. Dexmedetomidine, midazolam, and coadministration of dexmedetomidine with sevoflurane reduced wake-associated phase-amplitude coupling (P≤0.01). All sedatives except sevoflurane decreased wake-associated high gamma weighted phase-lag index (P<0.01).

CONCLUSIONS

In contrast to i.v. drugs, prolonged sevoflurane sedation produced minimal changes in sleep homeostasis and neural dynamics. Further studies are warranted to assess inhalational agents for long-term sedation and sleep homeostasis.

Clinical Use of Adrenergic Receptor Ligands in Acute Care Settings

In this chapter, we review how ligands, both agonists and antagonists, for the major classes of adrenoreceptors, are utilized in acute care clinical settings. Adrenergic ligands exert their effects by interacting with the three major classes of adrenoceptors. Adrenoceptor agonists and antagonists have important applications, ranging from treatment of hypotension to asthma, and have proven to be extremely useful in a variety of clinical settings of acute care from the operating room to the critical care environment. Continued research interpreting the mechanisms of adrenoreceptors may help the discovery of new drugs with more desirable clinical profiles.

The nuts and bolts of multimodal anaesthesia in the 21st century: a primer for clinicians

PURPOSE OF REVIEW

This review article explores the application of multimodal anaesthesia in general anaesthesia, particularly in conjunction with locoregional anaesthesia, specifically focusing on the importance of EEG monitoring. We provide an evidence-based guide for implementing multimodal anaesthesia, encompassing drug combinations, dosages, and EEG monitoring techniques, to ensure reliable intraoperative anaesthesia while minimizing adverse effects and improving patient outcomes.

RECENT FINDINGS

Opioid-free and multimodal general anaesthesia have significantly reduced opioid addiction and chronic postoperative pain. However, the evidence supporting the effectiveness of these approaches is limited. This review attempts to integrate research from broader neuroscientific fields to generate new clinical hypotheses. It discusses the correlation between high-dose intraoperative opioids and increased postoperative opioid consumption and their impact on pain indices and readmission rates. Additionally, it explores the relationship between multimodal anaesthesia and pain processing models and investigates the potential effects of nonpharmacological interventions on preoperative anxiety and postoperative pain.

SUMMARY

The integration of EEG monitoring is crucial for guiding adequate multimodal anaesthesia and preventing excessive anaesthesia dosing. Furthermore, the review investigates the impact of combining regional and opioid-sparing general anaesthesia on perioperative EEG readings and anaesthetic depth. The findings have significant implications for clinical practice in optimizing multimodal anaesthesia techniques (Supplementary Digital Content 1: Video Abstract, http://links.lww.com/COAN/A96 ).

Ventricular Tachycardia Following Ephedrine During Dexmedetomidine Dental Procedural Sedation

We present the case of a 46-year-old man who received ephedrine for hypotension after surgery for a mandibular lesion under intravenous (IV) moderate sedation with dexmedetomidine (DEX) and experienced transient ventricular tachycardia (VT). The patient was scheduled to have cystectomy and multiple apicoectomies for the mandibular periapical infection and the simple bone cyst. Other than obesity, snoring, and a nonalcoholic fatty liver, he denied any other significant medical history, medications, or allergies. The surgery was successful; however, his blood pressure dropped after stopping the DEX infusion. Ephedrine was administered IV several times, which resulted in the onset of VT on the electrocardiogram (ECG). His blood pressure could not be measured at the time, but he was able to respond and breathe independently. A defibrillator was immediately made available. The ECG revealed a spontaneous transition from VT to atrial fibrillation with ST depression. Because he was unable to revert to a normal sinus rhythm, the patient was transferred to a general hospital, where he underwent additional testing. No abnormalities were observed in his heart or brain. After DEX administration, its long-lasting alpha-2 adrenoceptor agonist effects can cause vasodilation and inhibition of sympathetic activity, leading to hypotension in some patients. Should that occur, ephedrine can be used to increase blood pressure, but it may also provoke transient coronary artery spasms and lead to VT. Consequently, extreme caution should be exercised in patients who develop hypotension following DEX administration. We also recognize the significance of regular training sessions, such as advanced cardiac life support programs.

Clinical observation of dexmedetomidine nasal spray in the treatment of sleep disorders on the first night after undergoing maxillofacial surgery: a single-center double-blind randomized controlled study

Purpose: Dexmedetomidine exerts a sedative effect by promoting the sleep pathway endogenously and producing a state similar to N2 sleep. This study aimed to study the efficacy and safety of dexmedetomidine nasal spray in the treatment of postoperative sleep disturbance. Methods: This study enrolled 120 participants [men and women; age, 18-40 years; American Society of Anesthesiologists grade, I or II] who underwent maxillofacial surgery under general anesthesia through nasotracheal intubation. The participants were randomly divided into three groups: blank control group (BC group), 1.0 μg/kg dexmedetomidine group (1.0 Dex group), and 1.5 μg/kg dexmedetomidine group (1.5 Dex group), with 40 patients allocated to each group. At 21:30 on the night after the operation, the intervention groups were administered their corresponding doses of dexmedetomidine nasal spray. The Pittsburgh Sleep Quality Index (PSQI) scale was used to evaluate the baseline sleep status of participants 1 month preoperatively and on the night after the operation. Polysomnography (PSG) was used to record the sleep status on the night after the operation. We recorded the rescue times of sedative and analgesic drugs on the first night after surgery, adverse reactions, total hospital stay duration, and total costs. Results: Compared with patients in the BC group, those in 1.0 Dex and 1.5 Dex groups had longer N2 sleep duration, were awake for a shorter time after dose administration, woke up less often, and had significantly improved sleep efficiency (p < 0.05). Compared with the BC group, the PSQI scores of 1.0 Dex and 1.5 Dex groups were significantly lower on the night after operation, and the proportion of PSQI > 5 was significantly lower (p < 0.05). Compared with patients in the BC group and the 1.0 Dex group, those in the 1.5 Dex group had significantly prolonged N3 sleep, reduced frequency of requiring sufentanil rescue, lower incidence of sore throat after surgery, and shorter average length of hospital stay (all, p < 0.05). Conclusion: The sleep quality of participants on the night after having undergone maxillofacial surgery was safely and effectively improved by 1.0-1.5 μg/kg dexmedetomidine atomized nasal sprays. Notably, only the latter could prolong N3 sleep. Level of Evidence II: Evidence was obtained from at least one properly designed randomized controlled trial.

Dexmedetomidine Improved Sleep Quality in the Intensive Care Unit After Laryngectomy

Purpose

To examine whether nighttime dexmedetomidine infusion improved sleep quality in patients after laryngectomy.

Patients and Methods

Thirty-five post-laryngectomy patients admitted to the intensive care unit (ICU) were randomly assigned to a 9-h (from 2100 h on surgery day to 0600 h the morning after laryngectomy) dexmedetomidine (0.3 μg/kg/h continuous infusion) or placebo group. Polysomnography results were monitored during the dexmedetomidine infusion period. The percentage of stage 2 non-rapid eye movement (stage N2) sleep was the primary outcome measure.

Results

Thirty-five patients (18 placebo group; 17 dexmedetomidine group) had complete polysomnogram recordings. The percentage of stage N3 sleep was significantly increased in the dexmedetomidine infusion group (from median 0% (0 to 0) in placebo group to 0% (interquartile range, 0 to 4) in dexmedetomidine group (difference, -2.32%; 95% CI, -4.19 to -0.443; P = 0.0167)). Infusion had no effect on total sleep time, stage N1 or N2 sleep percentages, or sleep efficiency. It decreased muscle tensity and snore non-rapid eye movement. Subjective sleep quality improved. Hypotension incidence increased in the dexmedetomidine group, but significant intervention was not required.

Conclusion

Dexmedetomidine infusion improved overall patient sleep quality in the ICU after laryngectomy.

Effects of dexmedetomidine on postoperative sleep quality: a systematic review and meta-analysis of randomized controlled trials

STUDY OBJECTIVES

To assess the effect of dexmedetomidine (DEX) on postoperative sleep quality using polysomnography (PSG) to identify possible interventions for postoperative sleep disturbances.

METHODS

An electronic search of PubMed/MEDLINE, EMBASE, Cochrane Library and Web of Science was conducted from database inception to November 20, 2022. Randomized controlled trials (RCTs) on the effect of DEX administration on postoperative sleep quality using PSG or its derivatives were included. No language restrictions were applied. The sleep efficiency index (SEI), arousal index (AI), percentages of stage N1, N2 and N3 of non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep were measured in our meta-analysis.

RESULTS

Five studies, involving 381 participants were included. Administration of DEX significantly improved SEI, lowered AI, decreased the duration of stage N1 sleep and increased the duration of stage N2 sleep compared to placebo groups. There were no significant differences in the duration of stage N3 sleep and REM sleep. DEX administration lowered the postoperative Visual Analogue Scale (VAS) score and improved the Ramsay sedation score with no adverse effect on postoperative delirium (POD). However, high heterogeneity was observed in most of the primary and secondary outcomes.

CONCLUSIONS

Our study provides support for the perioperative administration of DEX to improve postoperative sleep quality. The optimal dosage and overall effect of DEX on postoperative sleep quality require further investigation using large-scale randomized controlled trials.

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.

Nighttime dexmedetomidine for delirium prevention in non-mechanically ventilated patients after cardiac surgery (MINDDS): A single-centre, parallel-arm, randomised, placebo-controlled superiority trial

BACKGROUND

The delirium-sparing effect of nighttime dexmedetomidine has not been studied after surgery. We hypothesised that a nighttime dose of dexmedetomidine would reduce the incidence of postoperative delirium as compared to placebo.

METHODS

This single-centre, parallel-arm, randomised, placebo-controlled superiority trial evaluated whether a short nighttime dose of intravenous dexmedetomidine (1 μg/kg over 40 min) would reduce the incidence of postoperative delirium in patients 60 years of age or older undergoing elective cardiac surgery with cardiopulmonary bypass. Patients were randomised to receive dexmedetomidine or placebo in a 1:1 ratio. The primary outcome was delirium on postoperative day one. Secondary outcomes included delirium within three days of surgery, 30-, 90-, and 180-day abbreviated Montreal Cognitive Assessment scores, Patient Reported Outcome Measures Information System quality of life scores, and all-cause mortality. The study was registered as NCT02856594 on ClinicalTrials.gov on August 5, 2016, before the enrolment of any participants.

FINDINGS

Of 469 patients that underwent randomisation to placebo (n = 235) or dexmedetomidine (n = 234), 75 met a prespecified drop criterion before the study intervention. Thus, 394 participants (188 dexmedetomidine; 206 placebo) were analysed in the modified intention-to-treat cohort (median age 69 [IQR 64, 74] years; 73.1% male [n = 288]; 26·9% female [n = 106]). Postoperative delirium status on day one was missing for 30 (7.6%) patients. Among those in whom it could be assessed, the primary outcome occurred in 5 of 175 patients (2.9%) in the dexmedetomidine group and 16 of 189 patients (8.5%) in the placebo group (OR 0.32, 95% CI: 0.10-0.83; P = 0.029). A non-significant but higher proportion of participants experienced delirium within three days postoperatively in the placebo group (25/177; 14.1%) compared to the dexmedetomidine group (14/160; 8.8%; OR 0.58; 95% CI, 0.28-1.15). No significant differences between groups were observed in secondary outcomes or safety.

INTERPRETATION

Our findings suggested that in elderly cardiac surgery patients with a low baseline risk of postoperative delirium and extubated within 12 h of ICU admission, a short nighttime dose of dexmedetomidine decreased the incidence of delirium on postoperative day one. Although non-statistically significant, our findings also suggested a clinical meaningful difference in the three-day incidence of postoperative delirium.

FUNDING

National Institute on Aging (R01AG053582).

Effect of mini-dose dexmedetomidine supplemented intravenous analgesia on sleep structure in older patients after major noncardiac surgery: A randomized trial

STUDY OBJECTIVES

In previous studies, low-dose dexmedetomidine supplemented opioid analgesia improved sleep architecture but increased sedation level. Herein we tested the hypothesis that mini-dose dexmedetomidine supplemented analgesia improves sleep structure without increasing sedation.

METHODS

In this randomized trial, 118 older patients (≥65 years) following major noncardiac surgery were randomized to receive patient-controlled intravenous analgesia supplemented with either placebo or dexmedetomidine (median 0.02 μg kg^-1 h^-1) for up to 3 days. Polysomnogram was monitored from 9:00 p.m. on the day of surgery until 6:00 a.m. on the first day after surgery. Our primary outcome was the percentage of non-rapid eye movement stage 2 (N2) sleep. Secondary outcomes included other sleep structure parameters during the night of surgery and the sedation score during the first five postoperative days.

RESULTS

All 118 patients completed the study; of these, 85 were included in sleep structure analysis. Dexmedetomidine supplemented analgesia increased the percentage of N2 sleep (median difference, 10%; 95% CI, 1%-20%; P = 0.03). It also prolonged total sleep time (median difference, 78 min; 95% CI, 21 to 143; P = 0.01), increased sleep efficiency (median difference, 14%; 95% CI, 4%-26%; P = 0.01), decreased percentage of N1 sleep (median difference, -10%; 95% CI, -20% to -1%; P = 0.04), and lowered sleep fragmentation index (median difference, -1.6 times⋅h^-1; 95% CI, -3.7 to 0.1; P = 0.04). Sedation score within 5 days did not differ between the two groups.

CONCLUSIONS

Supplementing intravenous analgesia with mini-dose dexmedetomidine improved sleep structure without increasing sedation in older patients recovering from major surgery.

CLINICAL TRIALS

www.

CLINICALTRIALS

gov (NCT03117790), registered 2 April 2017.

Could dexmedetomidine be repurposed as a glymphatic enhancer?

Cerebrospinal fluid (CSF) flows through the central nervous system (CNS) via the glymphatic pathway to clear the interstitium of metabolic waste. In preclinical studies, glymphatic fluid flow rate increases with low central noradrenergic tone and slow-wave activity during natural sleep and general anesthesia. By contrast, sleep deprivation reduces glymphatic clearance and leads to intracerebral accumulation of metabolic waste, suggesting an underlying mechanism linking sleep disturbances with neurodegenerative diseases. The selective α₂-adrenergic agonist dexmedetomidine is a sedative drug that induces slow waves in the electroencephalogram, suppresses central noradrenergic tone, and preserves glymphatic outflow. As recently developed dexmedetomidine formulations enable self-administration, we suggest that dexmedetomidine could serve as a sedative-hypnotic drug to enhance clearance of harmful waste from the brain of those vulnerable to neurodegeneration.

Dexmedetomidine-mediated sleep phase modulation ameliorates motor and cognitive performance in a chronic blast-injured mouse model

Multiple studies have shown that blast injury is followed by sleep disruption linked to functional sequelae. It is well established that improving sleep ameliorates such functional deficits. However, little is known about longitudinal brain activity changes after blast injury. In addition, the effects of directly modulating the sleep/wake cycle on learning task performance after blast injury remain unclear. We hypothesized that modulation of the sleep phase cycle in our injured mice would improve post-injury task performance. Here, we have demonstrated that excessive sleep electroencephalographic (EEG) patterns are accompanied by prominent motor and cognitive impairment during acute stage after secondary blast injury (SBI) in a mouse model. Over time we observed a transition to more moderate and prolonged sleep/wake cycle disturbances, including changes in theta and alpha power. However, persistent disruptions of the non-rapid eye movement (NREM) spindle amplitude and intra-spindle frequency were associated with lasting motor and cognitive deficits. We, therefore, modulated the sleep phase of injured mice using subcutaneous (SC) dexmedetomidine (Dex), a common, clinically used sedative. Dex acutely improved intra-spindle frequency, theta and alpha power, and motor task execution in chronically injured mice. Moreover, dexmedetomidine ameliorated cognitive deficits a week after injection. Our results suggest that SC Dex might potentially improve impaired motor and cognitive behavior during daily tasks in patients that are chronically impaired by blast-induced injuries.

A randomized placebo-controlled double-blind study of dexmedetomidine on postoperative sleep quality in patients with endoscopic sinus surgery

Background

Postoperative sleep disorder is common and may cause aggravated postoperative pain, delirium, and poor prognosis. We accessed the effect of intraoperative intravenous dexmedetomidine on postoperative sleep quality in patients with endoscopic sinus surgery. 

Methods

This single-center, double-blind, placebo-controlled randomized clinical trial enrolled a total of 110 participants aged 18 years to 65 years who were scheduled to receive endoscopic sinus surgery. Placebo (normal saline) or dexmedetomidine infusion (load dose 0.5 μg kg⁻¹ over 10 min, followed by maintenance dose 0.2 ug kg⁻¹ h⁻¹) during surgery. The primary outcome was postoperative sleep quality. Secondary outcomes were postoperative Ramsay sedation scores, Visual Analog Scale (VAS) scores, serum cortisol, 5-hydroxytryptamine (5-HT) and hypocretin, delirium, and postoperative nausea and vomiting (PONV).

Results

Among enrolled 110 patients, 55 were randomized to administer intraoperative dexmedetomidine and placebo. In total, 14 patients (7 in each group) were excluded because of protocol deviations, and 96 patients (48 in each group) were included in the per-protocol analysis. The dexmedetomidine group had a significantly higher sleep efficiency index(SEI) (66.85[3.00] vs 65.38[3.58]), the ratio of rapid eye movement sleep to total sleep(REM)(13.63[1.45] vs 12.38[2.11]) and lower arousal index (AI) (7.20[1.00] vs 8.07[1.29]), higher Ramsay sedation score at post-operation 1 h, 12 h point, lower VAS scores at post-operation 1 h, 12 h, 24 h point, lower cortisol, higher 5-HT and hypocretin in serum than the placebo group.

Conclusion

In this randomized clinical trial, dexmedetomidine can improve the sleep quality of patients undergoing endoscopic sinus surgery. These results suggest that this therapy may be a viable strategy to enhance postoperative sleep quality in patients with endoscopic sinus surgery.

Trial registration

The study was approved by the Bethune International Peace Hospital Ethics Committee (2021-KY-129) and registered in the Chinese Clinical Trial Registry (ChiCTR2100051598, 28/09/2021). 

Recent Advances in the Clinical Value and Potential of Dexmedetomidine

Dexmedetomidine, a highly selective α2-adrenoceptor agonist, has sedative, anxiolytic, analgesic, sympatholytic, and opioid-sparing properties and 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. Recent studies indicate several emerging clinical applications via different routes. We review recent data on dexmedetomidine studies, particularly exploring the varying routes of administration, experimental implications, clinical effects, and comparative advantages over other drugs. A search was conducted on the PubMed and Web of Science libraries for recent studies using different combinations of the words “dexmedetomidine”, “route of administration”, and pharmacological effect. The current routes, pharmacological effects, and application categories of dexmedetomidine are presented. It functions by stimulating pre- and post-synaptic α2-adrenoreceptors within the central nervous system, leading to hyperpolarization of noradrenergic neurons, induction of an inhibitory feedback loop, and reduction of norepinephrine secretion, causing a sympatholytic effect, in addition to its anti-inflammation, sleep induction, bowel recovery, and sore throat reduction effects. Compared with similar α2-adrenoceptor agonists, dexmedetomidine has both pharmacodynamics advantage of a significantly greater α2:α1-adrenoceptor affinity ratio and a pharmacokinetic advantage of having a significantly shorter elimination half-life. In its clinical application, dexmedetomidine has been reported to present a significant number of benefits including safe sedation for various surgical interventions, improvement of intraoperative and postoperative analgesia, sedation for compromised airways without respiratory depression, nephroprotection and stability of hypotensive hemodynamics, reduction of postoperative nausea and vomiting and postoperative shivering incidence, and decrease of intraoperative blood loss. Although the clinical application of dexmedetomidine is promising, it is still limited and further research is required to enhance understanding of its pharmacological properties, patient selection, dosage, and adverse effects.

Sleep, Pain, and Cognition: Modifiable Targets for Optimal Perioperative Brain Health

The prevention of perioperative neurocognitive disorders is a priority for patients, families, clinicians, and researchers. Given the multiple risk factors present throughout the perioperative period, a multicomponent preventative approach may be most effective. The objectives of this narrative review are to highlight the importance of sleep, pain, and cognition on the risk of perioperative neurocognitive disorders and to discuss the evidence behind interventions targeting these modifiable risk factors. Sleep disruption is associated with postoperative delirium, but the benefit of sleep-related interventions is uncertain. Pain is a risk factor for postoperative delirium, but its impact on other postoperative neurocognitive disorders is unknown. Multimodal analgesia and opioid avoidance are emerging as best practices, but data supporting their efficacy to prevent delirium are limited. Poor preoperative cognitive function is a strong predictor of postoperative neurocognitive disorder, and work is ongoing to determine whether it can be modified to prevent perioperative neurocognitive disorders.

Postoperative delirium mediates 180-day mortality in orthopaedic trauma patients

BACKGROUND

Frailty has been associated with increased incidence of postoperative delirium and mortality. We hypothesised that postoperative delirium mediates a clinically significant (≥1%) percentage of the effect of frailty on mortality in older orthopaedic trauma patients.

METHODS

This was a single-centre, retrospective observational study including 558 adults 65 yr and older, who presented with an extremity fracture requiring hospitalisation without initial ICU admission. We used causal statistical inference methods to estimate the relationships between frailty, postoperative delirium, and mortality.

RESULTS

In the cohort, 180-day mortality rate was 6.5% (36/558). Frail and prefrail patients comprised 23% and 39%, respectively, of the study cohort. Frailty was associated with increased 180 day mortality from 1.4% to 12.2% (11% difference; 95% confidence interval [CI], 8.4-13.6), which translated statistically into an 88.7% (79.9-94.3%) direct effect and an 11.3% (5.7-20.1%) postoperative delirium mediated effect. Prefrailty was also associated with increased 180 day mortality from 1.4% to 4.4% (2.9% difference; 2.4-3.4), which was translated into a 92.5% (83.8-99.9%) direct effect and a 7.5% (0.1-16.2%) postoperative delirium mediated effect.

CONCLUSIONS

Frailty is associated with increased postoperative mortality, and delirium might mediate a clinically significant, but small percentage of this effect. Studies should assess whether, in patients with frailty, attempts to mitigate delirium might decrease postoperative mortality.

Perioperative Sleep Disorder: A Review

Patients in the perioperative period usually present with different types and degrees of sleep disorders, which can severely affect their post-operative outcomes. Multiple risk factors may lead to the occurrence of perioperative sleep disorders, including personal factors, psychological factors, surgery factors, and environmental factors. In this review, we summarize the potential risk factors for perioperative sleep disorders during hospitalization. And it also provides an overview of perioperative outcomes and potential therapeutic prevention of perioperative sleep disorders. However, the further search is necessary to investigate the effectiveness and safety of preventions in the clinical practice and push forward the therapies.

Effect of Dexmedetomidine on Postoperative Sleep Quality: A Systematic Review

In this article, we conduct a systematic review of the literature to explore the specific role of dexmedetomidine (DEX) on postoperative sleep and its associated mechanisms at present. The electronic database Embase, MEDLINE/PubMed, the Cochrane Library, Web of Science, and Google Scholar were searched. The restriction terms included “dexmedetomidine”, “sleep” and “surgery”. The inclusion criteria were as following: 1) patients 18 years old or older; 2) DEX used in the perioperative period not just for critically ill patients in the intensive care unit (ICU); 3) prospective or retrospective studies. The review articles, conference abstracts, and animal studies were excluded. Out of the 22 articles which met the above criteria, 20 of them were randomized controlled studies and 2 of them were retrospective cohort studies. Infusion of DEX including during the surgery and after surgery at a low or high dose was shown to improve subjective and objective sleep quality, although 2 studies showed there is no evidence that the use of DEX improves sleep quality and 1 showed less sleep efficiency and shorter total sleep time in the DEX group. Other postoperative outcomes evaluated postoperative nausea and vomiting, pain, postoperative delirium bradycardia and hypotension. Outcomes of our systematic review showed that DEX has advantages in improving patients’ postoperative sleep quality. Combined with the use of general anesthetic, DEX provides a reliable choice for procedural sedation.

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.