Beta-endorphin, cortisol and postoperative delirium: a preliminary report

Area of Science:

• Neuroscience
• Endocrinology
• Critical Care Medicine

Background:

• Postoperative delirium is a common complication in intensive care units (ICUs).
• The neuroendocrine mechanisms underlying post-surgical delirium remain incompletely understood.

Purpose of the Study:

• To investigate the association between postoperative delirium and the neuroendocrine stress response.
• To examine the impact of surgery on circadian rhythms of beta-endorphin and cortisol in delirious versus non-delirious patients.

Main Methods:

• Plasma levels of beta-endorphin and cortisol were measured in patients undergoing elective surgery in an ICU.
• Measurements were taken preoperatively and throughout the 48-72 hour postoperative period.
• Patients were monitored for the occurrence of transient delirium, characterized by hallucinations and disorientation.

Main Results:

• Delirious patients exhibited significantly prolonged postoperative increases in beta-endorphin and cortisol levels.
• Normal plasma circadian rhythms of beta-endorphin and cortisol were disrupted in delirious patients.
• Non-delirious patients showed no significant elevation in mean 24-hr hormone levels, and their circadian rhythms remained largely intact, though phase-shifted.

Conclusions:

• Disruption of circadian rhythms in the endogenous opiate and hypothalamic-pituitary-adrenal (HPA) axis is associated with postoperative delirium.
• These neuroendocrine changes may play a crucial role in the psychological alterations observed in ICU patients post-surgery.