Pharmacological Risk Factors for Delirium after Cardiac Surgery: A Review

PURPOSE:

The objective of this review is to
evaluate the literature on medications associated with delirium after
cardiac surgery and potential prophylactic agents for preventing it.

SOURCE:

Articles
were searched in MEDLINE, Cumulative Index to Nursing and Allied
Health, and EMBASE with the MeSH headings: delirium, cardiac surgical
procedures, and risk factors, and the keywords: delirium, cardiac
surgery, risk factors, and drugs. Principle inclusion criteria include
having patient samples receiving cardiac procedures on cardiopulmonary
bypass, and using DSM-IV-TR criteria or a standardized tool for the
diagnosis of delirium.

PRINCIPAL FINDINGS:

Fifteen
studies were reviewed. Two single drugs (intraoperative fentanyl and
ketamine), and two classes of drugs (preoperative antipsychotics and
postoperative inotropes) were identified in the literature as being
independently associated with delirium after cardiac surgery. Another
seven classes of drugs (preoperative antihypertensives,
anticholinergics, antidepressants, benzodiazepines, opioids, and
statins, and postoperative opioids) and three single drugs
(intraoperative diazepam, and postoperative dexmedetomidine and
rivastigmine) have mixed findings. One drug (risperidone) has been shown
to prevent delirium when taken immediately upon awakening from cardiac
surgery. None of these findings was replicated in the studies reviewed.

CONCLUSION:

These
studies have shown that drugs taken perioperatively by cardiac surgery
patients need to be considered in delirium risk management strategies.
While medications with direct neurological actions are clearly
important, this review has shown that specific cardiovascular drugs may
also require attention. Future studies that are methodologically
consistent are required to further validate these findings and improve
their utility.