Neurologic Illness and Critical Care

In a critically ill patient, an abnormal mental status has been associated with a higher mortality rate and a longer stay in the intensive care unit (ICU). Normally, patients should be aware of their surroundings and themselves and have an accurate perception of what they are experiencing. A patient should be able to process information into judgment and reasoning and store and retrieve information as memory. Orientation, judgment and reasoning, and memory constitute cognition. Therefore, disorders of awareness or mental status can be classified as problems with consciousness or cognition.