Definitions

Conscious - Appearance of wakefulness, awareness of the self and environment

Unconscious - Sleep like appearance and behaviorally unresponsive to all external stimuli

Levels of conciousness - Refers to the level or degree of alertness. Although not true levels or steps, the following terms describe a progressives worsening in the degree of a patient's alertness

Only the terms for the two extremes of levels of conciousness, alert and coma can be used to unequivocally describe a patient's level of consciousness. Terms like lethargy, obtundation, and stupor are too broad to enable you to adequately describe a patient's condition so that another observer knows exactly what you have seen. A subtle worsening in level of conciousness may signal an unstable patient that is ready to "crash" and require emergency intervention