Postoperative+Delirium+in+Elderly

toc =Incidence= =Definition= =Pathophysiologic mechanism= =Risk Factors= =Management= Cornerstone of management is identifying and treating the predisposing and/or precipitating factors
 * Varies depending on type of surgery.
 * estimated to be 10% in elderly after major elective surgery.
 * Incidence is higher than 10% after cardiac surgery and hip fx repair.
 * Review of data between 1966-1992 show delirium to be 36.8% for all types of surgery
 * Incidence (not prevalence) = important predictor of higher costs and increased duration of hospital stay.
 * DSM-IV - "The essential feature of delirium is a disturbance in the consciousness that is accompanied by a change in cognition that cannot be better accounted for by a preexisting or evolving dementia
 * Criteria
 * Disturbance of consciousness (i.e. reduced clarity of awareness of environment) with reduced ability to focus, sustain, or shift attention
 * A change in cognition (e.g, memory deficit, disorientation, language disturbance) or the development of a perceptual disturbance that is not better accounted for by a preexisting, established, or evolving dementia
 * The disturbance develops over a short time (usually hours to days) and tends to fluctuate during the course of the day
 * There is evidence from the history, physical examination, or laboratory findings that the disturbance is caused by the direct physiologic consequences of a general medical condition
 * Mechanism not fully understood
 * delirium epitomizes an atypical presentation of a disease in which process is manifested in vulnerable organ system ie -brain
 * Lack of "brain reserve" predisposes eldery to delirium when exposed to stressors
 * Most significant preoperative risk factors include
 * 1) advancing age (>70 yrs)
 * 2) preoperative cognitive impairment
 * 3) decreased functional status
 * 4) alcohol abuse
 * 5) previous history of deliriium
 * Risk model for delirium in medical patients, Charpentier and Inouye showed that the most important risk factors were
 * 1) visual impairment
 * 2) severe illness
 * 3) cognitive impairment
 * 4) dehydration
 * Intraoperative factors predictive of postoperative delirium
 * 1) surgical blood loss
 * 2) HCT < 30%
 * 3) # of intraoperative blood transfusions
 * Hemodynamic derangements, Nitrous oxide, and anesthetic technique have not been shown to increase the risk of postoperative delirium
 * Recent studies demonstrate that interventions of standardized protocols for risk factors (cognitive impairment, sleep deprivation, immobility, visual impairment, hearing impairment and dehydration) result in significant reductions # and duration of episodes of delirium in hospitalized elderly.
 * Anesthetic -specific interventions include
 * correcting metabolic and electrolyte disorders
 * perioperative continuation of medications for neuropsychiatric disorders
 * removing triggers (anticholinergics) or pain
 * alterations in blood transfusion

Reference: Miller, Ronald et al. __Miller's Anesthesia.__ 7th ed. 2009 Churchill Livingstone

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