Anaesthesia essentials: Overview

Abstract
Psychedelic drugs, known for their perception-altering properties, are gaining popularity in the treatment of mental health and pain disorders. As exploratory studies demonstrate clinical efficacy with few adverse events, it is expected that more patients will ingest psychedelic drugs. For therapeutic reasons, as with any drug, anaesthesiologists must be aware of its physiological effects and contraindications to ensure the safe provision of anaesthesia. Psilocybin is a 5HT1A and 5HT2A serotonin receptor agonist thought to act on excitatory and inhibitory neurons in the brain. Acute ingestion causes sympathetic nervous system activation, which can precipitate haemodynamic instability. Activation of the 5HT serotonin receptors can also place the patient at risk of serotonin syndrome. Chronic use increases plasma concentrations of cortisol, which has implications on prophylactic stress-dosing of glucocorticoids preoperatively. Lysergic acid diethylamide (LSD), a synthetic psychoactive substance, is also a 5HT2A agonist. LSD has been shown to potentiate opioid analgesics, and monoamine oxidase (MAO) inhibition. Historical reports suggest that LSD has anticholinesterase activity and can prolong neuromuscular block with depolarising muscle relaxants. Mescaline is a poorly understood psychedelic with similar autonomic effects. Historical studies have shown decreased neuromuscular transmission and an association with malignant hyperthermia. When managing patients who have consumed psychedelics drugs, it is important to consider delaying surgery whenever possible, to allow acute intoxication to wane. A high degree of suspicion and an understanding of management principles is vital to the safe conduct of anaesthesia. Future research should explore therapeutic doses of psychedelic drugs to understand physiologic effects at various concentrations

Abstract
Background: There are concerns whether (repeated) exposure to general anaesthesia is associated with long-term cognitive decline.

Objective: We investigated the potential, negative relationship between total exposure to surgery under general anaesthesia and its impact on long-term cognitive development.

Design: A prospective longitudinal cohort study.

Setting: The Netherlands.

Participants: 1823 Adults, aged 25-84 with normal cognitive functioning on inclusion with three serial cognitive assessments between 1995 and 2008, with comprehensive documentation on demographic, lifestyle, and health factors.

Main outcome measures: The primary outcomes were test scores in the cognitive domains of learning and memory, executive function, selective attention, mental speed, and information processing speed. Linear mixed models were used to analyse the effects of the estimated total time under general anaesthesia at baseline on cognitive development during a 12-year follow-up period.

Results: When adjusting for demographic and systemic health-related factors, prolonged exposure to surgery under general anaesthesia (measured in total baseline minutes) negatively affected three cognitive domains. These included the CST (executive functioning, P < 0.05), Stroop (selective attention and mental speed, P < 0.001) and LDST (information processing speed, P < 0.005). Age and education were the primary factors impacting lifetime cognitive decline. Hypertension, diabetes, and smoking negatively affected various cognitive domains.

Conclusion: Increased exposure to surgery under general anaesthesia independently contributes to long-term cognitive decline. Demographic variables and health-related factors are key contributors to accelerated cognitive decline over an individual's lifetime.