Cerebral autoregulation after aneurysmal subarachnoid haemorrhage. A preliminary study comparing dexmedetomidine to propofol and/or midazolam

Progress on the Mechanisms and Neuroprotective Benefits of Dexmedetomidine in Brain Diseases

INTRODUCTION

Dexmedetomidine, a highly specific α2 agonist, has been extensively utilized in clinical sedation and surgical anesthesia since its introduction in 2000 due to its excellent sympatholytic, sedative, and analgesic effects. This review aimed to identify new approaches for the treatment of patients with brain disorders by thoroughly describing the mechanism of action of dexmedetomidine and examining its neuroprotective effects from the standpoints of basic and clinical research.

METHODS

The PubMed and Web of Science databases were searched using the keywords dexmedetomidine and related brain diseases, although relevant articles from the last decade were included for detailed summarization and analysis.

RESULTS

Dexmedetomidine has shown strong neuroprotective effects, such as protection of the blood-brain barrier, decreased neuronal death, maintained hemodynamic stability, and reduced postoperative agitation and cognitive dysfunction. Furthermore, dexmedetomidine has been shown to exert various neuroprotective effects, including anti-inflammatory and antioxidative stress effects, modulation of autophagy, and reduction of apoptosis in cerebral diseases.

CONCLUSIONS

Dexmedetomidine acts as a neuroprotective agent against brain diseases during all phases of treatment. However, clinical trials with larger sample sizes are required to optimize dosage and dosing strategies.

The Impact of Sedative Choice in the Management of Aneurysmal Subarachnoid Hemorrhage: A Scoping Review

Aneurysmal subarachnoid hemorrhage (aSAH) is characterized by high mortality and morbidity. This scoping review assesses the current evidence regarding the use of sedatives and analgesics in the acute intensive care unit management of aSAH. We conducted a systematic search of Ovid MEDLINE, Ovid Embase, Ovid EmCare, APA PsycInfo, CINAHL, and the Cochrane Database of Systematic Reviews from inception to June 2023. Studies were included if they enrolled intensive care unit patients aged 18 or older with a significant proportion (> 20%) who had aSAH and evaluated the impact of one or more commonly used analgosedatives on physiological parameters in the management of aSAH. The methodological quality of the studies was assessed using the Methodological Index for Nonrandomized Studies score. Of 2,583 articles, 11 met the inclusion criteria. The median sample size was 47 (interquartile range 10-127), and the median Methodological Index for Nonrandomized Studies score was 9.5 (interquartile range 8-11). The studies' publication years ranged from 1980 to 2023. Dexmedetomidine and ketamine showed potential benefits in reducing the incidence of cortical spreading depolarization and delayed cerebral ischemia. Propofol and opioids appeared safe but lacked robust evidence for efficacy. Benzodiazepines were associated with increased delayed cerebral ischemia-related cerebral infarctions and cortical spreading depolarization events. The evidence available to guide the use of analgosedative medications in aSAH is critically inadequate. Dexmedetomidine and ketamine warrant further exploration in large-scale prospective studies because of their potential benefits. Improved study designs with consistent definitions and a focus on patient-centered outcomes are necessary to inform clinical practice.

The glymphatic system and subarachnoid hemorrhage: disruption and recovery

The glymphatic system, or glial-lymphatic system, is a waste clearance system composed of perivascular channels formed by astrocytes that mediate the clearance of proteins and metabolites from the brain. These channels facilitate the movement of cerebrospinal fluid throughout brain parenchyma and are critical for homeostasis. Disruption of the glymphatic system leads to an accumulation of these waste products as well as increased interstitial fluid in the brain. These phenomena are also seen during and after subarachnoid hemorrhages (SAH), contributing to the brain damage seen after rupture of a major blood vessel. Herein this review provides an overview of the glymphatic system, its disruption during SAH, and its function in recovery following SAH. The review also outlines drugs which target the glymphatic system and may have therapeutic applications following SAH.

Anesthetic Effect of Dexmedetomidine in Clinical Functional Neurosurgery

Background

Dexmedetomidine is a highly selective and efficient α2-adrenoceptor agonist with good antianxiety, analgesic, hypnotic, and sedative effects without causing respiratory depression.

Aim

To investigate the anesthetic effect of dexmedetomidine in clinical neurosurgery.

Methods

A total of 94 patients who received functional neurosurgical treatment in our hospital from March 2019 to October 2020 were selected and divided into the study and control groups. Routine anesthesia was adopted in the control group, while dexmedetomidine was used in the study group. Perioperative hemodynamic indicators such as mean arterial pressure, heart rate, and peripheral capillary oxygen saturation, cognitive function score, pain score VAS, stress response index level, and incidence of adverse reactions were compared between the two groups.

Results

Before surgery (T0), no significant differences in MAP, HR, and SpO2 were observed between the two groups. However, at the beginning of the operation (T1), 30 min after the operation (T2), and immediately after the operation (T3), these indicators in the study group were significantly higher than in the control group. The postoperative MMSE of the study group 3 d later was significantly higher than that of the control group. The VAS scores after the operation of the study group were lower than those of the control group. The serum cortisol (COR) and aldosterone (ALD) levels in the study group were not significantly different from those in the control group before surgery. The levels of each index in the two groups were higher than those before and 24 h after surgery. The incidence rate of adverse reactions in the study group was lower.

Conclusion

The application of dexmedetomidine in clinical functional neurosurgery is safe and can maintain hemodynamic stability and reduce the degree of stress response, cognitive impairment, and pain caused by invasive surgery.