Anaesthesia essentials: Overview

Regional Anesthesia & Pain Medicine, the official publication of the American Society of Regional Anesthesia and Pain Medicine (ASRA Pain Medicine), is a monthly journal that publishes peer-reviewed scientific and clinical studies to advance the understanding and clinical application of regional techniques for surgical anesthesia and postoperative analgesia. Coverage includes intraoperative regional techniques, perioperative pain, chronic pain, obstetric anesthesia, paediatric anesthesia, outcome studies, and complications.

Abstract
Background: Administration of conventional anaesthetic agents is associated with changes in electroencephalogram (EEG) oscillatory dynamics, including a reduction in the peak alpha frequency. Computational models of neurones can reproduce such phenomena and are valuable tools for investigating their underlying mechanisms. We hypothesised that EEG data acquired during xenon anaesthesia in humans would show similar changes in peak alpha frequency and that computational neuronal models of recognised cellular actions of xenon would be consistent with the observed changes.

Methods: EEG recordings were obtained for 11 participants from a randomised controlled trial of xenon anaesthesia and for 21 participants from a volunteer study of xenon administration. The frontal peak alpha frequency was calculated for both cohorts at awake baseline and during xenon administration. In silico simulations with two computational models of neurones were performed to investigate how xenon antagonism of hyperpolarisation-activated cyclic nucleotide-gated channel 2 (HCN2) and glutamatergic excitatory neurotransmission would influence peak alpha frequency.

Results: Compared with awake baseline, frontal peak alpha frequency was significantly lower during xenon administration in the randomised controlled trial cohort, median (inter-quartile range) frequency 7.73 Hz (7.27-8.08 Hz) vs 8.81 Hz (8.35-9.03 Hz), P=0.012, and the volunteer cohort, 8.69 Hz (8.34-8.98 Hz) vs 9.41 Hz (9.11-9.92 Hz), P=0.001. In silico simulations with both computational models suggest that antagonism of HCN2 and glutamatergic excitatory neurotransmission are associated with a reduction in peak alpha frequency.

Conclusions: Xenon administration is associated with a reduction of peak alpha frequency in the frontal EEG. In silico simulations utilising two computational models of neurones suggest that these changes are consistent with antagonism of HCN2 and glutamatergic excitatory neurotransmission.

Clinical trial registration: The Australian New Zealand Clinical Trials Registry: ANZCTR number 12618000916246.

Abstract
Anaesthesia is integral to a wide range of clinical procedures; however, there is a global challenge in the anaesthesia workforce due to several contributing factors. This study seeks to assess the knowledge and perceptions of medical students regarding anaesthesia as a specialty. Understanding these perspectives is essential to addressing the global shortage of anaesthesia professionals. PubMed, Scopus, African Journal Online, and ProQuest were searched from the database inception to July 2024 to identify relevant studies. A total of 2,575 articles were identified. After title and abstract screening, 2,137 articles were excluded. After full-text screening, 2,098 articles were excluded. Eight articles were included in this qualitative analysis. We included primary studies published in peer-reviewed journals that reported the perception and choice of anaesthesiology as a future career by medical students in their clinical years (years five and six), with reasons, irrespective of medical institution, age, or gender, were included. In total, 2,135 students from six countries were included in the eight studies: Pakistan, Saudi Arabia, Nigeria, Austria, the United States of America, and South Africa, with Nigeria and Saudi Arabia each contributing two studies. The study designs utilised included cross-sectional surveys, descriptive cross-sectional studies, and questionnaire-based studies. The mean age of the students ranged from 23 to 28 years across the studies, with 748 male students, 530 female students, and 857 students whose gender was not specified. A significant proportion of students were aware of the role of anaesthetists; however, only 178 students expressed an interest in specialising in anaesthesia, with the most common reason being a genuine interest in the specialty. The studies reviewed identified several reasons why students did not consider anaesthesiology as a preferred speciality, including limited patient contact, which affects the doctor-patient relationship, lack of recognition or respect from peers, low income, limited availability of local job opportunities or training positions, and the presence of anaesthetic nurses. A critical factor highlighted across all studies was the length of exposure to anaesthesia during clinical rotations. Medical students recognise the importance of anaesthetists but are often deterred from pursuing the specialty due to various factors, which could be mitigated through enhanced exposure, increased visibility, financial incentives, and mentorship.

Abstract
General anesthesia is a widely used medical practice, affecting more than 300 million patients annually. Despite its ubiquity, the underlying mechanisms through which anesthetic agents induce amnesia remain poorly understood. This review explores the impact of general anesthetics on memory function, with a particular focus on the role of neural oscillations in anesthesia-induced memory suppression. Neural oscillations, such as theta, gamma, delta oscillations, slow oscillations (SO), spindles, and sharp wave ripples (SWR), are critical for memory formation and consolidation. Various anesthetics modulate these oscillations in ways that affect memory, even at subanesthetic concentrations. We highlight recent findings on the molecular and electrophysiological mechanisms by which general anesthetics influence memory-related neural oscillations, including the inhibition of synaptic plasticity, alterations in spike-timing-dependent plasticity (STDP), and disruption of cross-frequency couplings like theta-gamma and SO-spindle-SWR. Additionally, the review addresses the significance of age in anesthesia-related memory loss, with elderly patients being particularly vulnerable to long-term cognitive decline. Electrophysiological techniques, such as Electroencephalography (EEG); and advanced neuromodulation techniques, such as chemogenetics, and optogenetics, have provided insights into the neural dynamics underpinning anesthesia-induced amnesia, yet the causal relationship between EEG rhythms and memory impairment remains to be fully elucidated. This review underscores the importance of further research into the interaction between anesthesia, neural oscillations, and memory. Understanding these mechanisms will not only advance theoretical knowledge of general anesthesia but also aid in the development of safer anesthetic strategies to mitigate postoperative cognitive dysfunction, especially in high-risk populations.