Postoperative Delirium

Type of surgery/reason for admission
Incidence of delirium
ICU care (surgical and medical patients >65 years old) [3]
70–87 %
Elective vascular surgery [1, 2]
34.5 % (29–39 %)
Cardiac surgery [4]
32 % (0–73 %)
Hip fracture [5]
21.7 % (4–53 %)
Elective hip or knee replacement [3]
12.1 % (9–28 %)
Major elective surgery [1, 2]
10 % (9–17 %)

Preoperative Evaluation

Certain patient populations are inherently vulnerable to developing delirium. In addition, the duration and physiologic stress of the surgery influence the likelihood of precipitating delirium. Inherent risk factors are shown in Table 46.2 [1, 2]. Cardiopulmonary bypass may be a surgery-specific risk factor for delirium associated with more protracted cognitive dysfunction, but studies in this area are heterogeneous. Current evidence suggests it is most important to focus on reducing patient-specific risk factors, rather than the form of surgery or anesthesia [7].
Table 46.2
Patient risk factors for delirium
Age > 65
Cognitive dysfunction, especially dementia
Prior stroke
Prior history of delirium
Depression
Reduced preoperative functional status
Vision and hearing impairment
Preoperative psychotropic drug use
HIV
Drug and alcohol abuse
Renal or liver disease
Male gender
Malnutrition
 

Perioperative Management

Prevention

Prevention trials utilizing behavioral and environmental approaches have demonstrated a reduction in delirium incidence (absolute risk reduction 5–18 %) [8, 9]. Geriatrics consultation has also been shown to be helpful [9]. Pharmacologic prevention trials in high-risk patients have not consistently shown a reduction in delirium incidence, but may affect duration and severity. In the absence of better data, prophylactic antipsychotics are not warranted for most patients [10]. Anticholinesterase inhibitors have not been shown to effectively prevent delirium. During postoperative ICU care, the use of dexmedetomidine instead of benzodiazepines for sedation has been associated with lower rates of delirium, but is more costly and associated with bradycardia [11]. Effective prevention strategies are shown in Table 46.3.
Table 46.3
Prevention of delirium in postoperative patients
Providing visual and hearing aids when appropriate
Early mobilization
Avoid volume depletion and electrolyte abnormalities
Discontinue or substitute high-risk medications
Frequent reorientation
Maintain day/night cycle by limiting naps, opening blinds, avoiding nighttime interruptions
Adequate pain control without oversedation
Consider geriatric consultation

Diagnosis

First, confirm the diagnosis of delirium by excluding other neurologic and psychiatric conditions. Then, focus on identifying precipitants with history, medication review, physical exam (particularly neurologic and cognitive exam), and basic lab tests (CBC, Chem 7, UA). When appropriate, ECG, CXR, drug levels, or a toxin screen may confirm a suspected etiology. Remember that the etiology may be multifactorial. Head CT scan is often not helpful unless there is a risk factor for intracranial bleeding (e.g., history of fall or anticoagulant use) or evidence of new focal neurologic impairment.

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Oct 6, 2016 | Posted by in RESPIRATORY | Comments Off on Postoperative Delirium

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