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Daily interruption of sedative therapy and limitation of deep sedation have been shown in several randomized trials to reduce the duration of mechanical ventilation and hospital length of stay, and to improve the outcome of critically ill patients. However, patients with severe acute brain injury (ABI; including subjects with coma after traumatic brain injury, ischaemic/haemorrhagic stroke, cardiac arrest, status epilepticus) were excluded from these studies. Therefore, whether the new paradigm of minimal sedation can be translated to the neuro-ICU (NICU) is unclear. In patients with ABI, sedation has ‘general’ indications (control of anxiety, pain, discomfort, agitation, facilitation of mechanical ventilation) and ‘neuro-specific’ indications (reduction of cerebral metabolic demand, improved brain tolerance to ischaemia). Sedation also is an essential therapeutic component of intracranial pressure therapy, targeted temperature management and seizure control. Given the lack of large trials which have evaluated clinically relevant endpoints, sedative selection depends on the effect of each agent on cerebral and systemic haemodynamics. Titration and withdrawal of sedation in the NICU setting has to be balanced between the risk that interrupting sedation might exacerbate brain injury (e.g. intracranial pressure elevation) and the potential benefits of enhanced neurological function and reduced complications. In this review, we provide a concise summary of cerebral physiologic effects of sedatives and analgesics, the advantages/disadvantages of each agent, the comparative effects of standard sedatives (propofol and midazolam) and the emerging role of alternative drugs (ketamine). We suggest a pragmatic approach for the use of sedation-analgesia in the NICU, focusing on some practical aspects, including optimal titration and management of sedation withdrawal according to ABI severity.

S-ketamine and midazolam are frequently used to provide sedation while maintaining spontaneous respiration. However, the effects of these agents on respiratory variability, which reflects the adaptability of the respiratory system, have not been thoroughly explored. We evaluated these effects in a randomized controlled pilot trial. This study was conducted as part of a randomized controlled trial originally designed to assess the effects of s-ketamine conditioning on pain sensitivity in patients with fibromyalgia syndrome. Participants were randomly assigned to receive an infusion of either s-ketamine (0.3 mg kg -1 h -1 ), midazolam (0.05 mg kg -1 h -1 ), or saline in a blinded fashion. Mean respiratory rate, variability of respiratory rate (VRR), and variability of tidal volume (VTV) were measured continuously and non-invasively with a bio-impedance method. Changes during drug infusion were compared in a linear mixed model to assess the effects of s-ketamine and midazolam compared to saline. Data were analyzed for 57 experiments in 28 participants. Their median baseline variabilities of respiratory rate and tidal volume were 0.19 (IQR: 0.16–0.25) and 0.23 (0.19–0.34), respectively. While mean respiratory rate was not affected, midazolam resulted in a significant decrease in both VRR (ß = −0.071, 95% CI: −0.120 to −0.021) and VTV (ß = −0.117, 95% CI: −0.170 to −0.062). In contrast, s-ketamine appeared to produce a smaller decrease in VTV (ß = −0.062, 95% CI: −0.118 to −0.003) with VRR remaining unaffected (ß = −0.036, 95% CI: −0.092 to 0.019). In conclusion, our study demonstrates that midazolam reduces respiratory variability, potentially impairing the adaptability of the respiratory system. In contrast, s-ketamine largely preserved respiratory variability, suggesting it may be a safer alternative for sedation in patients with impaired spontaneous breathing. Further studies are needed to assess the clinical implications of these observations in patients undergoing sedation.

Inhibitors of acetylcholinesterase (AChE), which have an important role in the prevention of excessive AChE activity and β-amyloid (Aβ) formation are widely used in the symptomatic treatment of Alzheimer's disease (AD). The inhibitory effect of anesthetic agents on AChE was determined by several approaches, including binding mechanisms, molecular docking and kinetic analysis. Inhibitory effect of intravenous anesthetics on AChE as in vitro and in vivo have been discovered. The midazolam, propofol and thiopental have shown competitive inhibition type (midazolam > propofol > thiopental) and Ki values were found to be 3.96.0 ± 0.1, 5.75 ± 0.12 and 29.65 ± 2.04 µM, respectively. The thiopental and midazolam showed inhibition effect on AChE in vitro, whereas they showed activation effect in vivo when they are combined together. The order of binding of the drugs to the active site of the 4M0E receptor was found to be midazolam > propofol > thiopental. This study on anesthetic agents that are now widely used in surgical applications, have provided a molecular basis for investigating the drug-enzyme interactions mechanism. In addition, the study is important in understanding the molecular mechanism of inhibitors that are effective in the treatment of AD.

Midazolam is a rapidly effective benzodiazepine drug that is widely used as a sedative worldwide. Due to its poor solubility in a neutral aqueous solution, the clinical use of midazolam is significantly limited. As one of the most promising formulations for poorly water-soluble drugs, nanocrystals have drawn worldwide attention. We prepared a stable nanosuspension system that causes little muscle irritation. The particle size of the midazolam nanocrystals (MDZ/NCs) was 286.6 ± 2.19 nm, and the crystalline state of midazolam did not change in the size reduction process. The dissolution velocity of midazolam was accelerated by the nanocrystals. The pharmacokinetics study showed that the AUC0–t of the MDZ/NCs was 2.72-fold (p < 0.05) higher than that of the midazolam solution (MDZ/S), demonstrating that the bioavailability of the MDZ/NC injection was greater than that of MDZ/S. When midazolam was given immediately after the onset of convulsions, the ED50 for MDZ/NCs was significantly more potent than that for MDZ/S and DZP/S. The MDZ/NCs significantly reduced the malondialdehyde content in the hippocampus of the seizures model rats and significantly increased the glutathione and superoxide dismutase levels. These results suggest that nanocrystals significantly influenced the dissolution behavior, pharmacokinetic properties, anticonvulsant effects, and neuroprotective effects of midazolam and ultimately enhanced their efficacy in vitro and in vivo.

Objective Spreading depolarizations (SD) are characterized by breakdown of transmembrane ion gradients and excitotoxicity. Experimentally, N -methyl- d -aspartate receptor (NMDAR) antagonists block a majority of SDs. In many hospitals, the NMDAR antagonist s-ketamine and the GABA A agonist midazolam represent the current second-line combination treatment to sedate patients with devastating cerebral injuries. A pressing clinical question is whether this option should become first-line in sedation-requiring individuals in whom SDs are detected, yet the s-ketamine dose necessary to adequately inhibit SDs is unknown. Moreover, use-dependent tolerance could be a problem for SD inhibition in the clinic. Methods We performed a retrospective cohort study of 66 patients with aneurysmal subarachnoid hemorrhage (aSAH) from a prospectively collected database. Thirty-three of 66 patients received s-ketamine during electrocorticographic neuromonitoring of SDs in neurointensive care. The decision to give s-ketamine was dependent on the need for stronger sedation, so it was expected that patients receiving s-ketamine would have a worse clinical outcome. Results S-ketamine application started 4.2 ± 3.5 days after aSAH. The mean dose was 2.8 ± 1.4 mg/kg body weight (BW)/h and thus higher than the dose recommended for sedation. First, patients were divided according to whether they received s-ketamine at any time or not. No significant difference in SD counts was found between groups (negative binomial model using the SD count per patient as outcome variable, p  = 0.288). This most likely resulted from the fact that 368 SDs had already occurred in the s-ketamine group before s-ketamine was given. However, in patients receiving s-ketamine, we found a significant decrease in SD incidence when s-ketamine was started (Poisson model with a random intercept for patient, coefficient − 1.83 (95% confidence intervals − 2.17; − 1.50), p  < 0.001; logistic regression model, odds ratio (OR) 0.13 (0.08; 0.19), p  < 0.001). Thereafter, data was further divided into low-dose (0.1–2.0 mg/kg BW/h) and high-dose (2.1–7.0 mg/kg/h) segments. High-dose s-ketamine resulted in further significant decrease in SD incidence (Poisson model, − 1.10 (− 1.71; − 0.49), p  < 0.001; logistic regression model, OR 0.33 (0.17; 0.63), p  < 0.001). There was little evidence of SD tolerance to long-term s-ketamine sedation through 5 days. Conclusions These results provide a foundation for a multicenter, neuromonitoring-guided, proof-of-concept trial of ketamine and midazolam as a first-line sedative regime.

Suicidality is a transdiagnostic entity in patients with and without psychiatric disorders. Ketamine is a novel treatment for treatment-resistant depression with favorable effects on related suicidality in this population. Little is known about the effects of ketamine on suicidality as a distinct phenomenon. To assess whether a dose of 75 mg intranasal (IN) ketamine reduces acute suicidality relative to a 4 mg intranasal dose of the active placebo midazolam, 180 min after administration. A double-blind randomized placebo-controlled trial (N = 100) will assess the efficacy of fixed-dose IN racemic ketamine in patients presenting with acute suicidality, regardless of psychiatric diagnosis. Participants receive a single IN dose of either racemic ketamine (75 mg) or midazolam (4 mg) along with treatment as usual. The primary outcome is the reduction in suicidal ideation as measured by the Beck Scale for Suicide Ideation (BSSI) at 180 min. Secondary outcomes include depression severity with the Montgomery Åsberg Depression Rating Scale (MADRS) and tolerability with the Systematic Assessment for Treatment Emerging Effects (SAFTEE) as well as blood-based and neuroimaging markers. This study design considers key aspects such as patient selection, ketamine formulation, clinical management, and the follow-up time points. Potential risks, limitations, and future considerations are additionally discussed. EudraCT 2020-002905-24, registered 6 October 2021.

Benzodiazepines are widely used in clinics and for recreational purposes, but will lead to addiction in vulnerable individuals. Addictive drugs increase the levels of dopamine and also trigger long-lasting synaptic adaptations in the mesolimbic reward system that ultimately may induce the pathological behaviour. The neural basis for the addictive nature of benzodiazepines, however, remains elusive. Here we show that benzodiazepines increase firing of dopamine neurons of the ventral tegmental area through the positive modulation of GABA A (γ-aminobutyric acid type A) receptors in nearby interneurons. Such disinhibition, which relies on α1-containing GABA A receptors expressed in these cells, triggers drug-evoked synaptic plasticity in excitatory afferents onto dopamine neurons and underlies drug reinforcement. Taken together, our data provide evidence that benzodiazepines share defining pharmacological features of addictive drugs through cell-type-specific expression of α1-containing GABA A receptors in the ventral tegmental area. The data also indicate that subunit-selective benzodiazepines sparing α1 may be devoid of addiction liability. Benzodiazepine addiction Psychoactive benzodiazepines are widely used clinically and recreationally and although considered safe and effective in the short term, they are addictive in some individuals. All addictive drugs studied so far act to increase dopamine levels in the mesolimbic area of the brain and to trigger adaptive synaptic plasticity in the ventral tegmental area. A new study shows that benzodiazepines, which act by binding to GABA A receptors, also increase firing of dopamine neurons of the ventral tegmental area through the positive modulation of α1-containing GABA A receptors in nearby interneurons. This in turn triggers drug-evoked synaptic plasticity in dopamine neurons. The data also suggest that subunit-selective benzodiazepines that do not activate α1 receptors may lack addictive properties. Benzodiazepines, such as valium, are used both in clinics and for recreational purposes, but lead to addiction in some individuals. Addictive drugs increase the levels of dopamine and trigger synaptic adaptations in the mesolimbic reward system, but the neural basis for the addictive nature of benzodiazepines remains elusive. Here, they are shown to increase firing of dopamine neurons in the ventral tegmental area through GABA A receptor activation in nearby interneurons.

Linkage between early-life exposure to anesthesia and subsequent learning disabilities is of great concern to children and their families. Here we show that early-life exposure to midazolam (MDZ), a widely used drug in pediatric anesthesia, persistently alters chromatin accessibility and the expression of quiescence-associated genes in neural stem cells (NSCs) in the mouse hippocampus. The alterations led to a sustained restriction of NSC proliferation toward adulthood, resulting in a reduction of neurogenesis that was associated with the impairment of hippocampal-dependent memory functions. Moreover, we found that voluntary exercise restored hippocampal neurogenesis, normalized the MDZ-perturbed transcriptome, and ameliorated cognitive ability in MDZ-exposed mice. Our findings thus explain how pediatric anesthesia provokes long-termadverse effects on brain function and provide a possible therapeutic strategy for countering them.

We sought to explore relationships of acute dissociative effects of intravenous ketamine with change in depression and suicidal ideation and with plasma metabolite levels in a randomized, midazolam-controlled trial. Data from a completed trial in suicidal, depressed participants (n = 40) randomly assigned to ketamine was used to examine relationships between ketamine treatment-emergent dissociative and psychotomimetic symptoms with pre/post-infusion changes in suicidal ideation and depression severity. Nonparametric correlational statistics were used. These methods were also used to explore associations between dissociative or psychotomimetic symptoms and blood levels of ketamine and metabolites in a subset of participants (n = 28) who provided blood samples immediately post-infusion. Neither acute dissociative nor psychotomimetic effects of ketamine were associated with changes in suicidal ideation or depressive symptoms from pre- to post-infusion. Norketamine had a trend-level, moderate inverse correlation with dissociative symptoms on Day 1 post-injection (P  = .064; P =.013 removing 1 outlier). Dehydronorketamine correlated with Clinician-Administered Dissociative States Scale scores at 40 minutes (P = .034), 230 minutes (P = .014), and Day 1 (P = .012). We did not find evidence that ketamine's acute, transient dissociative, or psychotomimetic effects are associated with its antidepressant or anti-suicidal ideation actions. The correlation of higher plasma norketamine with lower dissociative symptoms on Day 1 post-treatment suggests dissociation may be more an effect of the parent drug.

This systematic review synthesized literature evidence and compared midazolam’s risks and clinical outcomes with other sedatives in critically ill mechanically ventilated patients. We included randomized controlled trials (RCTs) from databases of PubMed, Embase, Cochrane Library, Web of Science, and CINAHL without language restrictions. We used relative risk (RR) for binary outcomes and standardized mean difference (SMD) for continuous outcomes, with corresponding 95% confidence interval (CI). 17 RCTs involving 1509 patients were included. Compared to other sedatives, midazolam significantly increased the incidence of delirium (RR 2.39, 95 % CI, 1.75 to 3.26), the time up to extubation (SMD 1.99, 95 % CI, 0.81 to 3.16) and ICU length of stay (SMD 0.63, 95 % CI, 0.20 to 1.08), but significantly reduced the incidence of bradycardia (RR 0.52, 95 % CI, 0.36 to 0.76). No differences were identified in hypotension incidence (RR 0.69, 95 % CI, 0.37 to 1.31) or duration of mechanical ventilation (SMD 0.28, 95 % CI, −0.22 to 0.78). Midazolam caused a higher risk of delirium, a longer time up to extubation, and ICU length of stay, but a lower incidence of bradycardia. No significant evidence indicated midazolam was associated with a higher risk of hypotension or increased duration of mechanical ventilation. Clinicians should balance midazolam’s potential risks with its benefits. While other sedatives may be catering to patients at a higher delirium risk, midazolam remains indispensable for hemodynamically compromised patients, such as those with bradycardia. Precise sedation management is crucial for patient safety and outcomes.