AoA Guided Thoracic Epidural Analgesia for Abdominal Aortic Repair

Open major abdominal surgery is one of the most risky surgical procedures performed under general anaesthesia (GA) for inappropriate postoperative pain perception (IPPP), whereas thoracic epidural analgesia (TEA) still constitutes the golden standard of analgesic regimen in the upper abdomen because its was proven to provide improved postoperative analgesia, reduce the incidence of chronic postoperative pain, as compared with parenteral opioids. Therefore, it should always be considered as a routine adjunct to GA for elective open lumbar infrarenal aortic repair (OLIAAR). Monitors of analgesia that measure nociception / antinociception balance - intensity of nociception (painful stimulation) and efficacy of anti-nociception (pain relief) - are increasingly gaining popularity. The Adequacy o Anesthesia (AoA) concept is based on monitoring the depth of GA detected from a forehead sensor using an entropy electroencephalogram (Response Entropy, RE; State Entropy, SE) and the surgical pleth index (SPI) derived from a finger photoplethysmography signal, both of which do not require complex preoperative preparations Observance of the SE value within the range of 40-60 as a result of proper administration of the hypnotic GA component, reflecting the proper suppression of the limbic system, alongside observance of the increase in the SPI value on the monitor (0-no painful stimulation, 100-maximum painful stimulation) after a painful stimulus and returning to the baseline level after the intravenous rescue opioid analgesia (IROA) bolus (anti-nociception), makes the monitoring with AoA guidance easy SPI has been successfully used to monitor analgesia intra- and postoperatively and less postoperative pain have already been reported, when SPI monitoring was employed. Considering all the above, the investigators designed a randomised controlled study to assess the effect of TEA using a combination of either 0,2 % ropivacaine (RPV) and fentanyl (FNT) or 0,2% bupivacaine (BPV) and FNT on intra- and postoperative demand for opioids, haemodynamic stability as compared to intravenous preventive analgesia using metamizole/tramadol in patients undergoing open lumbar infrarenal aortic aneurysm repair (OLIAAR) under AoA-guided GA