Selection of the anesthetic technique to be employed during a procedure begins during the preoperative evaluation with consideration of factors such as the patient’s comorbidities and preferences and the type of procedure to be performed. Oftentimes, general anesthesia is not necessary and the procedure can be performed under a lesser depth of sedation. Procedural sedation is a technique that allows the patient to tolerate the discomfort of a procedure while still maintaining cardiorespiratory function. In order to accomplish this, the anesthesia provider administers sedative, dissociative, and/or analgesic agents alone or in combination [1].

Preoperatively, the patient will transition from different depths of anesthesia, including the levels of sedation, to general anesthesia (GA). Sedation is a continuum of symptoms that range from minimal symptoms of anxiolysis to symptoms of moderate and deep sedation. Moderate sedation is defined by the patient remaining asleep, but being easily arousable. Deep sedation is achieved when the patient is only arousable to painful stimulation. GA refers to medically induced loss of consciousness with concurrent loss of protective reflexes and skeletal muscle relaxation. GA is most commonly achieved via induction with intravenous sedatives and analgesics, followed by maintenance of volatile anesthetics [1]. Table 9.1 lists the depths of anesthesia and associated characteristics.