Background
pain
Surgical procedures cause profound physiological changes, including hemodynamic, endocrine, and immune functions [Moreover, in elderly patients, homeostatic balance is more easily altered by exogenous stimuli [Monitoring devices for estimating the effect of nociception during general anesthesia have recently become commercially available [Therefore, this randomized controlled trial aimed to investigate whether there is a change in the perioperative outcomes caused by a difference in opioid administrations during surgery according to the SPI value versus hemodynamic parameters such as heart rate (HR) or blood pressure (BP) in elderly patients undergoing laparoscopic colorectal surgery. In addition, changes in inflammatory and immunologic markers were investigated for homeostatic imbalance analysis. We hypothesized that SPI-guided intraoperative analgesia would reduce intraoperative remifentanil consumption, allowing for earlier awakening and better immune function with a similar pain level after surgery.