Anesthesia has traditionally meant the condition of having sensation (including the feeling of pain) blocked. This allows patients to undergo surgery and other procedures without the distress and pain they would otherwise experience.
Patients undergoing surgery usually undergo preoperative evaluation. It includes gathering history of previous anesthetics, and any other medical problems, physical examination, ordering required blood work and consultations prior to surgery.
There are several forms of anesthesia. The following forms refer to states achieved by anesthetics working on the brain:
- General anesthesia: "Drug-induced loss of consciousness during which patients are not arousable, even by painful stimulation." Patients undergoing general anesthesia can often neither maintain their own airway nor breathe on their own.
- Deep sedation/analgesia: "Drug-induced depression of consciousness during which patients cannot be easily aroused but respond purposefully following repeated or painful stimulation." Patients may sometimes be unable to maintain their airway and breathe on their own.
- Moderate sedation/analgesia or conscious sedation: "Drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation." In this state, patients can breathe on their own and need no help maintaining an airway.
- Minimal sedation or anxiolysis: "Drug-induced state during which patients respond normally to verbal commands." Though concentration, memory, and coordination may be impaired, patients need no help breathing or maintaining an airway.