Aging Brain-Heart-Immune Axis and Postoperative Delirium: A Prospective Observational Study of Preoperative Heart Rate Variability Using At-home Wearable Devices

Postoperative delirium, a common complication in geriatric surgery patients, increases dementia¹risk and is linked to excessive postoperative inflammation.² The autonomic nervous system regulates inflammation via the brain–heart–immune axis.³ We hypothesize that a well-functioning brain–heart–immune axis protects against postoperative delirium by preventing excessive postoperative inflammation. In other disease states, enhanced brain–heart–immune axis function via vagus nerve stimulation reduces inflammation and symptom burden.⁴ Notably, perioperative vagus nerve stimulation in aged mice lowers systemic inflammation and improves postoperative task performance.⁵ In human patients, we can assess an autonomic component of brain–heart–immune axis function preoperatively by using wearable devices that measure heart rate variability, a noninvasive marker for autonomic function, and thereby evaluate whether brain–heart–immune axis function reflects a patient’s capacity to avoid excessive postoperative inflammation and postoperative delirium.