Hormonal responses to surgical stress

Area of Science:

• Physiology
• Endocrinology
• Anesthesiology

Background:

• Surgical stress activates the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system.
• Emergence from anesthesia is a significant stimulus for these stress responses.
• Understanding the hormonal regulation during surgery is crucial for patient outcomes.

Purpose of the Study:

• To investigate the relative contributions of surgery and anesthesia emergence to HPA axis and sympathetic nervous system activation.
• To elucidate the role of glucocorticoids, specifically cortisol, in modulating the stress response to surgery.
• To explore the interaction between glucocorticoids and catecholamines during the perioperative period.

Main Methods:

• Human studies assessing HPA axis and sympathetic nervous system activation during surgery and anesthesia emergence.
• Studies in adrenalectomized nonhuman primates receiving physiologic cortisol replacement.
• Measurement of cortisol levels and catecholamine activity in response to surgical stress.

Main Results:

• Anesthesia emergence is a more potent stimulus for HPA axis and sympathetic nervous system activation than the surgical procedure itself.
• Intraoperative HPA activation is typically moderate, with mild cortisol elevation correlating with an uncomplicated perioperative course.
• Cortisol replacement at a physiologic dose was necessary and sufficient for adrenalectomized nonhuman primates to tolerate surgical stress.

Conclusions:

• Glucocorticoids, particularly cortisol, appear to have a primarily permissive role in managing surgical stress.
• Catecholamines and glucocorticoids likely act synergistically to modulate the body's response to surgical stress.
• These findings highlight the importance of hormonal balance in perioperative stress management.