Dynamic perioperative changes in baroreflex sensitivity predict postoperative pain

Although higher baroreflex sensitivity (BRS) is typically associated with reduced pain sensitivity, we previously reported that elevated preoperative BRS predicted greater postoperative pain after cardiothoracic surgery, a finding that challenges existing experimental evidence. This exploratory secondary analysis tested whether perioperative changes in BRS (ΔBRS) better predict postoperative pain severity.

Exploratory secondary analysis of a prospective observational cohort.

Seventy-two adults undergoing elective minimally invasive cardiothoracic surgery.

Spontaneous cardiovagal BRS was measured preoperatively (pain-free baseline) and on postoperative days (POD) 1 and 2 (during ongoing pain). Pain severity was assessed using the PEG scale. Inflammatory biomarkers (C-reactive protein, cytokines, albumin) were also measured. Multivariable regression models evaluated associations between BRS metrics and pain, adjusting for demographic, surgical, analgesic, and psychological covariates.

Higher preoperative BRS was associated with greater postoperative BRS decline (ΔBRS) by POD2 (R2 = 0.12, P = 0.008) and with more severe pain on POD2 (R2 = 0.15, P = 0.003). ΔBRS was independently and inversely associated with pain severity (R2 = 0.09, P = 0.025) even after covariate adjustment. Although inflammatory markers increased postoperatively, they did not mediate these associations.

Steep perioperative BRS declines, particularly among individuals with initially high values, may reflect autonomic destabilization and reduced baroreflex-mediated inhibition of nociception. These findings identify ΔBRS as a dynamic and mechanistically informative predictor of postoperative pain. Perioperative BRS monitoring could support individualized risk stratification and guide interventions aimed at stabilizing autonomic function to improve recovery outcomes.