Evaluation of the effect of rectus sheath block and transversus abdomnis plan block on sevofluran and fentanyl consumption by entropy measurement in cases of laparoscopic cholecystectomy under general anesthesia: A prospective randomized study

In gallbladder surgery, the most commonly applied technique is laparoscopic cholecystectomy. In contemporary surgical interventions, general anesthesia is the most frequently used anesthesia method. Postoperative laparoscopic cholecystectomy, despite resulting in less postoperative pain and lower analgesic consumption compared to open cholecystectomy, is not a completely painless procedure. Peripheral blocks, encompassing a significant portion of postoperative analgesia due to the increasing clinical use of ultrasound in recent years, provide pain control in the early postoperative period and contribute to a reduction in systemic opioid use.The use of anesthesia depth monitoring has been proven to reduce drug consumption during anesthesia and facilitate faster wake-up and recovery after anesthesia. In this study, we aimed to compare the total amount of inhalation anesthetic consumed and the additional dose of fentanyl used at the end of laparoscopic cholecystectomy cases where general anesthesia was combined with ultrasound-guided abdominal wall peripheral nerve blocks (TAP and Rectus sheath block) and cases where it was not. We aimed to compare the total amount of inhalation anesthetic consumed at the end of the procedure and the additional dose of fentanyl used, while maintaining the depth of anesthesia monitored by "entropy" within the target range (40-60) Our study included 80 patients scheduled for elective laparoscopic cholecystectomy, ASA I-II, aged 18-75 years. Patients were divided into two groups: those who received general anesthesia combined with TAP and rectus sheath block, and those who received general anesthesia with analgesia provided by tramadol. Entropy monitoring was applied to both groups to maintain the entropy target value between 40-60 throughout the case. Parameters such as heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, oxygen saturation, end-tidal carbon dioxide values seen after orotracheal intubation, SE and RE entropy values, and end-tidal sevoflurane concentration (%) were recorded. At the end of the case, the total amount of inhalation agent consumed and the need for additional fentanyl were noted. When comparing the total amount of inhalation agent consumed throughout the entire case, it was observed to be 27.05±7.43ml in the control group and 12.25±4.34ml in the blocked group, with a statistically significant difference between the groups (p:0.002; p<0.05). Only 30% of patients required additional fentanyl during the intraoperative period. The need for intraoperative additional fentanyl and the total fentanyl consumed showed a significant difference between the groups. It was determined that more intraoperative additional doses of fentanyl were needed in Group I (control group) than in Group II (block group) (21 people in Group I, 3 people in Group II). In total, 115±33.62 µcg and 84±22.10 µcg fentanyl were consumed, respectively, and a significant statistical difference was detected between the two groups (p:0.000; p:0.001; p<0.05). In laparoscopic cholecystectomy cases, we observed that applying bilateral TAP and rectus sheath blocks standardized with an entropy monitor to general anesthesia reduced the consumption of inhalation anesthetic, intraoperative additional doses, and the total opioid requirement. Keywords: Laparoscopic Cholecystectomy, Transversus Abdominis Plane Block, Rectus Sheath Block, Entropy