Frances F. Chung, M.D.
Professor of Anaesthesia
University of Toronto
Toronto Western Hospital, Toronto, ON, Canada M5T 2S8
Frances.Chung@uhn.on.ca

Postoperative delirium, a transient mental dysfunction, can result in increased morbidity, delayed functional recovery and prolonged hospital stay in the elderly. The distinguishing features of this transient global disorder are impaired cognition, fluctuating levels of consciousness, altered psychomotor activity, and a disturbed sleep-wake cycle. It is usually seen on the first or second postoperative day and symptoms are often worse at night. The condition can be silent and go unnoticed, or it may be misdiagnosed as depression. The postoperative delirium are defined as clinical situations in which patients think and speak incoherently, are disoriented and show impairment of memory and attention. The Mini-Mental Status Exam (MMSE) and other tests can assess speech, consciousness, perception, orientation, coherence, memory and motor activity. The MMSE is easy to conduct, reliable and can be used for serial testing in fluctuating conditions.

The reported incidence of postoperative delirium varies from 1 percent to 61.3 percent in different studies. Differences in diagnostic criteria, populations under study and methods of surveillance used probably account for the wide range of figures. However, some surgeries such as joint replacement, are particularly likely to result in delirium. One hypothesis for the mechanism behind postoperative delirium is a decrease in the oxidative metabolism of the brain, which results in the decline of neurotransmitter levels within the brain and causes mental dysfunction. Another hypothesis suggests that an increase of serum cortisol from the stress of surgery or anesthesia may be responsible for postoperative confusion.

Aging, pathologic states in the brain, polypharmacy and drug interaction, alcohol and sedative-hypnotic withdrawal, endocrine and metabolic problem, depression, dementia and anxiety and gender are considered to be preoperative risk factors. Hypoperfusion and microemboli of air or blood cells in cardiac surgery, fat embolism in orthopedic surgical patients, regular use of anticholinergic drugs or drops and severe bilateral loss of vision in ophthalmologic patients may also contribute to the postoperative confusion. Anticholinergics, barbiturate premedication and benzodiazepines are implicated in the development of postoperative delirium. There is no difference in the effects of general, epidural or spinal anesthesia on postoperative confusion. Perioperative hypoxia, hypocarbia and sepsis are also risk factors for postoperative confusion.

Preoperative assessment of the patientās physical and mental status and medications is very important. Pre-existing sensory or perceptual deficits compound a patientās chances of developing confusional states. The mainstay of intraoperative preventive measures is maintaining good oxygenation, normal blood pressure, correct drug dosage and normal electrolyte levels. Drug cocktails should be avoided. Atropine, scopolamine and flurazepam should be used only if necessary, and the dose should be as low as possible. Glycopyrrolate may be a better choice than atropine as the former is a quaternary amine and should penetrate the blood-brain barrier less effectively than will atropine. Ambulatory surgery should be encouraged because elderly patients are maintained in the familiar home environment. Adequate postoperative analgesia, especially in patients who cannot communicate easily because of endotracheal tubes or tracheostomy, is crucial. Nurses should be well versed in detecting the earliest signs of delirium, which in the elderly may be withdrawal rather than agitation. The central nervous depressants, H2-antagonists, anticholinergics, digitalis, phenytoin, lidocaine and aminophylline should be used with discretion. In general, drugs with short elimination half-lives are preferable to long-acting drugs.

In all likelihood, patient predisposition, type of surgery and postoperative factors may be even more important to the development of delirium than the choice of anesthesia. Prevention of delirium will therefore involve control of many more factors than just the drugs used during surgery (though as mentioned above, certain classes of drugs should be avoided). Not much is known about prevention in surgical patients, but in hospitalized elderly medical patients a regimen designed to manage pre-existing cognitive impairment, sleep deprivation, immobility, visual impairment, hearing impairment and dehydration reduced the incidence of delirium to 10 percent in comparison to a 15-percent incidence in patients who received standard ward medical care.

Once postoperative confusion has been diagnosed, the patient should be managed with extra vigilance. First, the underlying organic cause of the confusion should be found and treated. For acute control of delirium, doses of 0.25-2 mg oral haloperidol 1-2 h before bedtime is the preferred treatment. For more agitated patients, IM haloperidol can be used. A small dose of 0.5 mg is given every hour until symptoms are adequately controlled. Droperidol has been used for rapid tranquilization. Although chlorpromazine is extremely effective, it can lead to a severe drop in blood pressure. Diazepam, used alone or in combination with other antipsychotic drugs, is especially effective for delirium tremens. Thiamine is the key drug for the management of Korsakoffās psychosis. Neither muscle relaxants nor physical restraints are particularly effective. Finally, if delirium progresses to coma, standard treatment for control of airway, breathing and circulation should be instituted. After recovery from an acute episode, a psychiatric or psychosocial referral may aid early functional rehabilitation. Similarly, the use of nursing assistance at home will permit a quicker discharge from the hospital. Physiotherapy and occupational therapy are also important adjuncts in the management of postoperative delirium.

A final concern that may be related to the phenomenon of postoperative delirium is the development of postoperative cognitive decline. Cognitive decline is not the same as delirium; patients who suffer cognitive loss are generally fully alert and oriented. In the past, changes in cognition have mostly been reported in an anecdotal fashion. More recently, a study that performed extensive neuropsychological testing demonstrated significant decrements in cognition in 10 percent of the subjects at three months after surgery. Age was the only significant risk factor. Whether the changes are permanent is unknown, nor is it apparent how it can be prevented.

Bibliography:

• Sullivan EM, Wanich CK, Kurlowicz LH. Nursing assessment, management of delirium in the elderly. AORN J. 1991; 53:824-828.
  
• Tune LE. Postoperative delirium. Int Psychogeriatr. 1991; 3:325-332.
  
• Chung F. Postoperative mental dysfunction. In: McLeskey CH, ed. Geriatric Anesthesiology. Williams & Wilkins; 1997:487-495.
  
• Folstein MF, Folstein SE, McHugh PR. "Mini-mental state." A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975; 12(3):189-198.
  
• Linn L, Kahn RL, Coles R, et al. Patterns of behaviour disturbance following cataract operation. Am J Psychiatr. 1953; 110:281-289.
  
• Seymour G. Acute and chronic confusional states in the elderly surgical patients. In: Medical Assessment of the Elderly Surgical Patient. Kent, England: Croom Helm; 1986:229-239.
  
• Gustafson Y, Brannstrom B, Berggren D, et al. A geriatric-anesthesiologic program to reduce acute confusional states in elderly patients treated for femoral neck fractures. J Am Geriatr Soc. l99l; 39:655-662.
• Williams-Russo P, Urquhart BL, Sharrock NE, Charlson ME. Post-operative delirium: Predictors and prognosis in elderly orthopedic patients. J Am Geriatr Soc. 1992; 40(8):759-767.
• Rogers MP, Liang MH, Daltroy LH, et al. Delirium after elective orthopedic surgery: Risk factors and natural history. Int J Psychiatry Med. 1989; 19:109-121.
• Blass JP, Gibson GE. Carbohydrates and acetylcholine synthesis: Implications for cognitive disorders. In: Davis KL, Berger PA, eds. Brain Acetylcholine and Neuropsychiatric Disease. New York: Plenum; 1979:215-236.
• Blass JP, Plum F. Metabolic encephalopathies in older adults. In: Katzman R, Terry R, eds. The Neurology of Aging. Philadelphia: FA Davis; 1983:189-220.
• McIntosh TK, Bush HL, Yeston NS, et al. Beta-endorphin, cortisol and postoperative delirium: A preliminary report. Psychoneuroendocrinology. 1985; 10:303-313.
• Moller JT, Cluitmans P, Rasmussen LS, et al. Long-term postoperative cognitive dysfunction in the elderly ISPOCD1 study. ISPOCD investigators. International Study of Post-Operative Cognitive Dysfunction. Lancet. 1998;3 51:357-361.
• Kaneko T, Takahashi S, Naka T, et al. Postoperative delirium following gastrointestinal surgery in elderly patients. Surg Today. 1997; 27:107-111.
• Seibert CP. Recognition, management, and prevention of neuropsychological dysfunction after operation. Int Anesthesiol Clin. 1986; 24(4):39-58.
• Larson EB, Kukull WA, Buchner D, Reifler BV. Adverse drug reactions associated with global cognitive impairment in elderly persons. Ann Intern Med. 1987; 107:169-173.
• Scott RB, Mitchell MC. Aging, alcohol and the liver. J Am Geriatr Soc. 1988; 36:255-265.
• Morgan K, Dallosso H, Ebrahim S, et al. Prevalence, frequency and duration of hypnotic drug use among the elderly living at home. Br Med J. 1988; 296:60l-602.
• Lambert SR, Benson D, Grosenick DJ, et al. Psychiatric manifestations of common endocrine disorders in the elderly. Psychiatr Med. 1984; 1(4):407-427.
• Lipov EG. Emergence delirium in the PACU. Crit Care Nurs Clin North Am. 1991; 3:145-149.
• Nevin M, Colchester AC, Adams S, Pepper JR. Evidence for involvement of hypocapnia and hypoperfusion in aetiology of neurological deficit after cardiopulmonary bypass. Lancet. 1987; 2(8574):1493-1495.
• Taylor KM. Brain damage during open-heart surgery. Thorax. 1982; 37(12):873-876.
• Eddy AC, Rice CL, Carrico CJ. Fat embolism syndrome. Monitoring and management. J Crit Illness. 1987; 2:24-37.
• Carpenter WT, Jr. Precipitous mental deterioration following cycloplegia with 0.2% cyclopentolate HCl. Arch Ophthalmol. l967; 78:445-447.
• Miller PS, Richardson JS, Jyu CA, et al. Association of low serum anticholinergic levels and cognitive impairment in elderly pre-surgical patients. Am J Psychiatry. 1988; 145:342-345.
• Lipowski ZJ. Delirium (acute confusional states). JAMA. 1987;258: 1789-1792.
• Castleden CM, George CF, Marcer D, Hallett C. Increased sensitivity to nitrazepam in old age. Br Med J. 1977; 1:10-12.
• Resnick M, Burton BT. Droperidol vs haloperidol in the initial management of acutely agitated patients. J CIin Psychiatry. 1984; 45:298-299.
• Ellison JM, Jacobs D. Emergency psychopharmacology: A review and update. Ann Emerg Med. 1986; 15:962-968.

return to top