Table 1.

Emergence from General Anesthesia and Stages of Recovery from Coma.^*

Emergence from General Anesthesia	Recovery from Coma
General anesthesia Stable administration of anesthetic drugs Arousal not possible, unresponsive; eyes closed, with reactive pupils Analgesia, akinesia Drug-controlled blood pressure and heart rate Mechanically controlled ventilation EEG patterns ranging from delta and alpha activity to burst suppression	Brain-stem death No respiratory response to apneic oxygenation test Total loss of brain-stem reflexes Isoelectric EEG pattern
	Coma Structural brain damage to both cerebral hemispheres, with or without injuries to tegmental midbrain, rostral pons, or both Isolated bilateral injuries to midline tegmental midbrain, rostral pons, or both Arousal not possible, unresponsive Functionally intact brain stem, normal arterial blood gases EEG pattern of low-amplitude delta activity and intermittent bursts of theta and alpha activity or possibly burst suppression
Emergence, phase 1 Cessation of anesthetic drugs Reversal of peripheral-muscle relaxation (akinesis) Transition from apnea to irregular breathing to regular breathing Increased alpha and beta activity on EEG	Vegetative state Spontaneous cycling of eye opening and closing Grimacing and nonpurposeful movements EEG pattern of high-amplitude delta and theta activity Absence of EEG features of sleep Usually able to ventilate without mechanical support
Emergence, phase 2 Increased heart rate and blood pressure Return of autonomic responsiveness Responsiveness to painful stimulation Salivation (7th and 9th cranial nerve nuclei) Tearing (7th cranial nerve nuclei) Grimacing (5th and 7th cranial nerve nuclei) Swallowing, gagging, coughing (9th and 10th cranial nerve nuclei) Return of muscle tone (spinal cord, reticulospinal tract, basal ganglia, and primary motor tracts) Defensive posturing Further increase in alpha and beta activity on EEG Extubation possible
Emergence, phase 3 Eye opening Responses to some oral commands Awake patterns on EEG Extubation possible	Minimally conscious state Purposeful guarding movements, eye tracking Inconsistent communication, verbalizations Following oral commands Return of sleep–wake cycles Recovery of some EEG features of normal sleep–wake architecture

^*EEG denotes electroencephalogram.