The psychiatrist in the surgical intensive care unit. I. Postoperative delirium.

Delirium has been defined as a condition of cerebral insufficiency consisting of impairment of cognitive processes, with a characteristic slowing of the electroencephalographic pattern. Present also is a global "clouding" of consciousness, resulting from a potentially reversible impairment of ability to maintain attention. In these states there is usually a simultaneous diminution of the ability to think, perceive, and remember. Although drowsiness may be a part of this state, patients can be awake and yet delirious, with diminished consciousness of their surroundings. Postoperative delirium is seen more often in patients over 50 years of age, in those who are "vigilant" or overalert, and in those undergoing more complex surgery. Adverse influences in the postoperative period are certain drugs and the psychological stresses engendered by the ICU environment. Appropriate management obtains from attention to the impact of the strange enviornment on the patient.