Effect of remifentanil infusion rate on stress response in orthopedic surgery using a tourniquet application

Background: Currently, in the field of general anesthesia, balanced anesthesia in combination with analgesic, hypnotic, and muscle relaxant is commonly used. Remifentanil is the standard analgesic used in balanced anesthesia, and has contributed greatly to reduce the physical stress of the patient during surgery. We compared the stress response suppression effect of remifentanil by measuring stress hormones in 2 groups treated with different analgesic doses in orthopedic surgery using a tourniquet. Methods: Twenty patients were randomly divided into 2 groups (10 patients each) undergoing maintenance of general anesthesia with 0.25 mu g/kg/min remifentanil and sevoflurane (Group A) and 1.0 mu g/kg/min remifentanil and sevoflurane (Group B). Hemodynamic changes, adrenocorticotropic hormone (ACTH), cortisol, antidiuretic hormone (ADH), adrenaline (Ad), noradrenaline (NAd), dopamine (DOA), insulin, and blood glucose were measured at the initiation of general anesthesia, 10 minutes after the initiation of tourniquet application, and immediately before and 10 minutes after the completion of tourniquet application. Results: ACTH, cortisol, ADH, Ad, and NAd levels in Group B were significantly lower (ACTH and cortisol: P < 0.01, ADH, Ad, and NAd: P < 0.05) than those in Group A. No significant differences were noted in DOA, insulin, or blood glucose levels between the groups. Conclusion: Anesthesia management with high-dose remifentanil (1.0 mu g/kg/min) suppressed intraoperative tourniquet pain-induced stress hormone release, suggesting its usefulness in stabilizing hemodynamics.