Repurposing General Anesthetic Drugs to Treat Depression: A New Frontier for Anesthesiologists in Neuropsychiatric Care.

During the last 100 years, the role of anesthesiologists in psychiatry has focused primarily on facilitating electroconvulsive therapy and mitigating postoperative delirium and other perioperative neurocognitive disorders. The discovery of the rapid and sustained antidepressant properties of ketamine, and early results suggesting that other general anesthetic drugs (including nitrous oxide, propofol, and isoflurane) have antidepressant properties, has positioned anesthesiologists at a new frontier in the treatment of neuropsychiatric disorders. Moreover, shared interest in understanding the biologic underpinnings of anesthetic drugs as psychotropic agents is eroding traditional academic boundaries between anesthesiology and psychiatry.

Discovering the Intriguing Properties of Extrasynaptic γ-Aminobutyric Acid Type A Receptors.

Tonic inhibition in mouse hippocampal CA1 pyramidal neurons is mediated by α5 subunit-containing γ-aminobutyric acid type A receptors. By Caraiscos VB, Elliott EM, You-Ten KE, Cheng VY, Belelli D, Newell JG, Jackson MF, Lambert JJ, Rosahl TW, Wafford KA, MacDonald JF, Orser BA. Proc Natl Acad Sci U S A 2004; 101:3662-7.

The Physician Anesthesia Workforce in Canada From 1996 to 2018: A Longitudinal Analysis of Health Administrative Data.

Background: A robust anesthesia workforce is essential to the provision of safe surgical, obstetrical, and critical care but information describing the physician anesthesia workforce and volume of clinical services delivered in Canada is limited. This study examines the Canadian physician anesthesia workforce, exploring trends in physician characteristics and activity levels over time. Practice patterns of specialist anesthesiologists and family physician anesthetists (FPAs) working in urban and rural communities were of particular interest.

Crosstalk between GABA receptors in astrocytes and neurons triggered by general anesthetic drugs.

General anesthetic drugs cause cognitive deficits that persist after the drugs have been eliminated. Astrocytes may contribute to such cognition-impairing effects through the release of one or more paracrine factors that increase a tonic inhibitory conductance generated by extrasynaptic γ-aminobutyric acid type A (GABA) receptors in hippocampal neurons. The mechanisms underlying this astrocyte-to-neuron crosstalk remain unknown.

Reduced excitatory neurotransmission in the hippocampus after inflammation and sevoflurane anaesthesia.

Background: Inflammation and general anaesthesia likely contribute to perioperative neurocognitive disorders, possibly by causing a neuronal imbalance of excitation and inhibition. We showed previously that treatment with lipopolysaccharide (LPS) and sevoflurane causes a sustained increase in a tonic inhibitory conductance in the hippocampus; however, whether excitatory neurotransmission is also altered remains unknown. The goal of this study was to examine excitatory synaptic currents in the hippocampus after treatment with LPS and sevoflurane.

Cell-surface biotinylation of GABA receptors in mouse hippocampal slices after sevoflurane anesthesia.

Here, we present a protocol for studying the cell-surface proteins in hippocampal slices after in vivo administration of sevoflurane, an inhaled general anesthetic drug, to mice. We describe steps for anesthetic delivery, hippocampal slice preparation, and cell-surface biotinylation. We then detail the isolation of surface proteins and their quantification through Western blotting.

Effect of inhaled anaesthetics on cognitive and psychiatric outcomes in critically ill adults: a systematic review and meta-analysis.

Background: Sedation of critically ill patients with inhaled anaesthetics may reduce lung inflammation, time to extubation, and ICU length of stay compared with intravenous (i.v.) sedatives.

The anesthesia workforce in Canada: a methodology to identify physician anesthesia providers using health administrative data.

Background: Safe and timely anesthesia services are an integral component of modern health care systems. There are, however, increasing concerns about the availability of anesthesia services in Canada. Thus, a comprehensive approach to assess the capacity of the anesthesia workforce to provide service is a critical need.

Proof-of-concept randomized controlled trial of single-session nitrous oxide treatment for refractory bipolar depression: Focus on cerebrovascular target engagement.

Background: There remain few efficacious treatments for bipolar depression, which dominates the course of bipolar disorder (BD). Despite multiple studies reporting associations between depression and cerebral blood flow (CBF), little is known regarding CBF as a treatment target, or predictor and/or indicator of treatment response, in BD. Nitrous oxide, an anesthetic gas with vasoactive and putative antidepressant properties, has a long history as a neuroimaging probe.

The Impact of Inflammation and General Anesthesia on Memory and Executive Function in Mice.

Background: Perioperative neurocognitive disorders (PNDs) are complex, multifactorial conditions that are associated with poor long-term outcomes. Inflammation and exposure to general anesthetic drugs are likely contributing factors; however, the relative impact of each factor alone versus the combination of these factors remains poorly understood. The goal of this study was to compare the relative impact of inflammation, general anesthesia, and the combination of both factors on memory and executive function.

Cognitive deficits after general anaesthesia in animal models: a scoping review.

Background: It remains controversial whether general anaesthetic drugs contribute to perioperative neurocognitive disorders in adult patients. Preclinical studies have generated conflicting results, likely because of differing animal models, study protocols, and measured outcomes. This scoping review of preclinical studies addressed the question: 'Do general anaesthetic drugs cause cognitive deficits in adult animals that persist after the drugs have been eliminated from the brain?'

Methods: Reports of preclinical studies in the MEDLINE database published from 1953 to 2021 were examined.

Perioperative Neurocognitive Screening Tools for At-Risk Surgical Patients.

Purpose Of Review: Perioperative neurocognitive disorders are common after surgery and have serious socioeconomic impacts. Despite this, these disorders remain under-recognized and underdiagnosed. To facilitate detection and direct patients toward appropriate preventative interventions, assessment of cognition during the perioperative period is of critical importance.