Chapter 12: General & Local Anaesthetics

General anaesthetics induce a complete loss of consciousness, body reflexes, and respiratory drive by progressively depressing sensory and motor functions of the central nervous system (CNS). These powerful drugs, including inhaled agents like sevoflurane and intravenous (IV) types like propofol, often leverage a multi-drug approach called balanced anaesthesia to maximize therapeutic effects and minimize dose-dependent adverse outcomes. The potency of these agents is linked to their lipid solubility, as described by the Overton–Meyer theory. A critical, genetically linked adverse event to watch for with general anaesthesia is malignant hyperthermia, characterized by a rapid elevation in body temperature and muscle rigidity, requiring treatment with dantrolene. In contrast, local anaesthetics, such as lidocaine (an amide), function regionally by interfering with nerve conduction to eliminate pain sensation without causing systemic CNS depression or loss of consciousness; these are administered via topical, infiltration, nerve block, or central spinal (intrathecal or epidural) techniques. Procedural sedation represents a middle ground, causing partial consciousness loss and marked anxiety reduction while generally preserving the patient's normal respiratory drive. Furthermore, Neuromuscular Blocking Drugs (NMBDs) are vital surgical adjuncts, providing skeletal muscle paralysis to facilitate intubation and controlled ventilation; these agents are categorized as either depolarizing (e.g., succinylcholine, which acts as a competitive agonist) or nondepolarizing (e.g., vecuronium, which acts as a competitive antagonist). Nursing management for all anaesthetic types requires stringent pre-anaesthesia assessments, focused on the patient's ABCs, organ function (especially liver/kidney), and history of conditions that affect drug metabolism, while post-anaesthesia care prioritizes continuous monitoring of respiratory and cardiovascular status, especially in high-risk groups like older adults and pediatric patients.