general anaesthesia

General anaesthesia (UK) or general anesthesia (US) is medically induced loss of consciousness that renders a patient unarousable even by painful stimuli. It is achieved through medications, which can be injected or inhaled, often with an analgesic and neuromuscular blocking agent.

General anaesthesia is usually performed in an operating theatre to allow surgical procedures that would otherwise be intolerably painful for a patient, or in an intensive care unit or emergency department to facilitate endotracheal intubation and mechanical ventilation in critically ill patients. Depending on the procedure, general anaesthesia may be optional or required. No matter whether the patient prefers to be unconscious or not, certain pain stimuli can lead to involuntary responses from the patient, such as movement or muscle contractions, that make the operation extremely difficult. Thus, for many procedures, general anaesthesia is necessary from a practical point of view.