Introduction: Opioids are the “gold standard” for pain treatment during and after colorectal surgery. They can inhibit cellular and humoral immunity and it is assumed that can promote cancer cell proliferation and metastatic spread. Adequate pain management can be achieved not only with opioids, but also with non-opioid drugs, which can be used together in small doses, i.e., multimodal analgesia, and can lower the need for opioids during and after surgery. Opioid free anesthesia (OFA) is part of multimodal analgesia, where opioids are not used in the intraoperative period.
Materials and methods: In this prospective and randomized clinical study 60 patients scheduled for open colorectal surgery were enrolled. They were between the ages of 45 and 70 with the American Association of Anesthesiologists (ASA) classifications 1, 2 and 3, divided in three groups. The first group of patients, or Opioid-based anesthesia group (OBAG), received the following for induction to anesthesia: lidocaine at 1 mg/kg, fentanyl 100 at µgr, propofol at 2mg/kg and rocuronium bromide at 0.6 mg/kg. They intermittently received 50-100 µgr fentanyl intravenously and 0.25 % bupivacaine 2-3 ml every 30-45 minutes, given in the epidural catheter during surgery. The second group of patients, or Low opioid anesthesia group (LOAG), received the following for induction to anesthesia: lidocaine at 1 mg/kg, fentanyl at 100 µgr, propofol at 2mg/kg and rocuronium bromide at 0.6 mg/kg. Prior to surgery, 50 µgr of fentanyl with 5 ml 0.25% bupivacaine was given into the epidural catheter, and the same dose was received at the end of surgery. The third group, or Opioid free anesthesia group (OFAG), received the following before the induction to general anesthesia: dexamethasone at 0.1 mg/kg and 1 gr of paracetamol. Induction to general anesthesia was with lidocaine at 1 mg/kg, propofol at 2mg/kg, ketamine at 0.5 mg/kg and rocuronium bromide at 0.6 mg/kg. After intubation, intravenous continuous infusion with lidocaine was at 2 mg/kg/h, ketamine 0.2 mg/kg/h and magnesium 15 mg/kg/h loaded on and intermittently 0.25 % bupivacaine 2-3 ml every 30-45 minutes given in the epidural catheter during surgery. The primary goal was to measure the patients’ pain after the first 72 postoperative hours in all three groups (2, 6, 12, 24, 36, 48 and 72 hours after surgery). The secondary goal was to measure the total amount of morphine given in the epidural catheter in the postoperative period in all three groups. Other secondary goals were: to compare the total amount of fentanyl given intravenously during surgery in the first and second groups, determine if there was a need to use rescue analgesia in the postoperative period, measure the occurrence of PONV, and to measure the total amount of bupivacaine given in the epidural catheter during operation in all three groups.
Results: Visual Analogue Scale (VAS) score comparisons between groups showed patients from the OBA and LOA groups had significantly higher VAS scores, compared to the patients from the OFA group 2, 12, 24 and 48 hours after operation. After 6 hours postoperatively, patients from the LOA group had significantly higher VAS scores, compared to patients from the OBA and OFA groups. After 36 hours postoperatively, patients from the OBA group had significantly higher VAS scores compared to patients from the LOA and OFA groups. At the last follow-up point, 72 hours after the intervention, the patients from the OBA and LOA groups had significantly higher VAS scores compared to the patients from the OFA group. All patients from the OBA and LOA groups, and only 9 from the OFA group received morphine in the postoperative period via epidural catheter. Patients from the Opioid group received significantly higher amounts of fentanyl during surgery. Additional administration of another analgesic drug in the postoperative period was prescribed in 55% of patients in the OBAG, in 50% in the LOAG and in 35% of the OFA group. PONV was registered in 60% of patients from the OBAG and in 40% of patients from the LOAG. In the OFA group did not register PONV in any of the patients. The biggest amount of bupivacaine given during surgery was in the OBAG (26.37 ± 2.6 mg), in LOAG was 25.0 ± 0 and the less in OFAG group (24.50 ± 4.3).
Conclusion: Patients from OFA group, compared with patients from OBAG and LOAG, have the lowest pain score in first 72 hours after open colorectal surgery, received fewer opioids via an epidural catheter in the postoperative period, had less need for rescue analgesia, no occurrence of PONV, and less need for bupivacaine via an epidural catheter in the intraoperative period.
