Postoperative Delirium
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Definition:
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DSM-IV definition: “a disturbance in consciousness that is
accompanied by a change in cognition that can not be better
accounted for by a pre-existing or evolving dementia.”
A global impairment of upper brain functions that involves
transient, fluctuating disturbances of consciousness,
attention, cognition, and perception.
Postoperative delirium often occurs acutely within 48-72
hrs after surgery and can pose danger to patient and/or
therapeutic surgical intervention
Symptoms often observed:
o Impaired consciousness – decreased awareness of
environment
o Cognitive impairment
o Emotional disturbances – anxiety, fear, irritability,
anger, etc.
o Disturbances of perception (therapeutic acts may
be erroneously interpreted as being harmful)
Incidence:
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Wide range of incidences cited 10-60% of noncardiac
surgery
Dependent on age of population studied, type of surgery,
duration of surgery, surgical risks of hypotension/hypoxia,
other co-morbidities
Associated with increased morbidity/mortality, including
postoperative cognitive dysfunction, functional impairment
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Hip replacement procedures (? 2/2
immobilization)
o Surgery > 10 hours
o Premed with benzodiazepine in elderly
(paradoxical effect)
Medications – preoperative/intraoperative/postoperative
(see Table 1)
Table 1. Drugs and Substances that May Cause Postoperative
Delirium
A. Analgesics
Codeine, Meperidine, Morphine.
B. Antibiotics
Acyclovir, Amphotericin B, Cephalosporins, Ciprofloxacin, Imipenen—cilastatin,
Ketoconazole, Metronidazole, Penicillin, Rifampin,
Trimethoprim—sulfamethoxazole.
C. Anticonvulsants
Phenobarbital, Phenytoin.
D. Cardiovascular drugs
Captopril, Clonidine, Digoxin, Dopamine, Labetalol, Lidocaine, Nifedipine,
Nitroprusside, Procainamide, Propranolol.
E. Drugs of abuse
Alcohol, Amphetamines, Cannabis, Cocaine, Hallucinogens, Inhalants, Opioids,
Phencyclidine, Sedatives, Hypnotics.
F. Corticosteroids
Dexamethasone, Methylprednisolone.
G. Miscellaneous Drugs
Hydroxyzine, Ketamine, Metoclopramide, Theophylline, Atropine, Scopolamine,
Benzodiazepines, Nonsteroidal anti-inflammatory agents.
(Cavaliere, F et al. Postoperative Delirium)
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No significant difference between regional vs general
anesthesia (Bryson, G. Evidence-based clinical update)
Environmental factors
Pathophysiology/Underlying Causes:
Treatment/Mangement:
1.
2.
3.
4.
5.
6.
Dopamine – Anticholinergic Imbalance:
a. Reciprocal relationship
b. Delirium caused when ↑ dopaminergic systems
and ↓ cholinergic activity
c. Anticholinergic syndrome
d. Scopolamine/atropine premed, meperidine
Metabolic alterations: acid-base disturbance, electrolyte
abnormalities (hyper/hyponatremia), infection,
hyperthermia, vitamin deficiency states (vitamin D),
alterations in melatonin/circadian rhythm
Hypoventilation – hypercarbia/hypoxia
Pain/Inadequate analgesia
a. Urinary urgency, gastric distension/NGT, tight
dressings, infiltrated IVs, corneal abrasion
Intoxication/Withdrawl – EtOH, benzodiazepenes, nicotine
Residual neuromuscular blockade
1.
Torsades de Pointes and QT prolongation,
some fatal, have been associated with the
use of haloperidol, haloperidol decanoate,
and haloperidol lactate, especially when
administered intravenously (not an approved
route of administration)
2.
Risk Factors:
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3.
Age
Underlying dementia
Previous history of postoperative delirium
Others
o Vascular surgery (? 2/2 risks of blood pressure
lability/hypotension intraop, risks of cerebral
atherosclerosis)
Antipsychotics – antagonize dopamine-mediated
neurotransmission (D2)
a. Butyrophenones – Haloperidol (1-2 mg bolus q
2-4 hrs; 0.2-0.5 mg in elderly patients) &
Droperidol
i. Black Box Warning for Halperidol –
4.
5.
b. Atypical Neuroleptics – no controlled studies
Benzodiazepenes
a. No studies demonstrate effectiveness as sole
agent apart from delirium 2/2
EtOH/benzodiazepine withdrawal
b. Used to augment treatment with antipsychotic
Anticholinergic – Physostigmine 2 mg IV (no faster than 1
mg/min)
a. Monitor for vagotonic state
Dexmedetomidine
Environmental Factors
a. Orientation – maintenance of glasses/hearing aids
b. Avoidance of overstimulation/understimulation