Discussion
delirium, colorectal cancer, postoperative pain, tachycardia, postoperative delirium, cardiovascular disease, arrhythmia, pain, trauma
COLORECTAL CANCER, CARDIOVASCULAR DISEASE, ARRHYTHMIA, INTRAOPERATIVE HYPERTENSION, EVENTS, HYPERTENSION, CORONARY ARTERY DISEASE, INFLAMMATORY RESPONSE
In this study, we found that in elderly patients, SPI-guided remifentanil administration during laparoscopic colorectal cancer surgery under general anesthesia was significantly higher than that in the conventional analgesia practices, resulting in lower intraoperative hypertension and tachycardia events without compromising postoperative pain and recovery in the PACU.These results suggest several important points regarding SPI-guided analgesia in elderly patients. First and foremost, contrary to the hypotheses for our study, the results differ from those of previous studies [The cardiovascular response to pain appears blunted in the elderly during general anesthesia for reasons such as decreased myocardial contractility, myocardial and vascular elasticity, baroreceptor reflex activity, and β-adrenergic response [PPGA and HBI influence the SPI value, and the PPGA is affected by vascular wall distensibility and intravascular pulse pressure [As a result, these characteristics may keep the SPI target range of 20–50 to properly reflect intraoperative nociception in patients of this study, resulting in more remifentanil consumption in the SPI group than in the control group. Similarly, due to the blunted autonomic responses, conventional analgesia responding to hemodynamic response can be under-dosed in the elderly patients. In contrast, SPI guided analgesia may provide a more appropriate level of analgesia with sufficient remifentanil dose.Second, In the SPI-guided analgesia group, there was less postoperative pain and analgesic consumption in the PACU as a result of the appropriate analgesia during surgery and the incidence of delirium in the PACU was significantly lower. These findings suggest that reducing pain during and after surgery, via intraoperative SPI-guided analgesia may be a factor that can reduce postoperative delirium [Third, our study differs from previous studies in that it excluded patients with cardiovascular disease or those taking medications that interfered with the cardiovascular response and prevented SPI values based on PPGA and HBI from deteriorating. However, most elderly patients have comorbidities, such as DM, hypertension, and coronary artery disease, without arrhythmia [Surgical stress is characterized by an inflammatory response with immune suppression, and surgical trauma initiates a cascade of reactions involving the immune response and nociception [This study has several limitations. First, because of the study design, staff in the operation room could not be blinded to the group assignment. However, the investigators who conducted follow-ups outside the operating room, including laboratory investigations and postoperative data assessment, were unaware of the patient’s group assignment. Second, the vasoactive agents (ephedrine, phenylephrine, and nicardipine) used in this study may affect SPI values by alternating the PPGA and HBI, which may interfere with the interpretation of proper SPI values [