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General anesthesia is a reversible state characterized by unconsciousness, analgesia, muscle relaxation, and depression of reflexes which is achieved by the administration of chemical agents1. It is a balance between the amount of anesthetic drugs administered and the state of arousal of the patient. As the intensity of surgical stimulation varies during a surgical procedure, so does the requirement of anesthetic agents. The organ system effects of anesthetic drugs may limit the amount that can be given safely. This would, at occasions, create a critical imbalance between anesthetic requirement and anesthetic drug administration resulting in varying depth of anesthesia.

Awareness during anesthesia (unintended intraoperative awareness) occurs when a patient can recall some or all of the events happening during a surgical procedure. The history of awareness dates back to the history of general anesthesia itself …