Intraoperative Analgesia Based on ANI

Osteoarthritis of the knee joint is common and total knee arthroplasty (TKA) is performed in patients with advanced joint degeneration, no response to conservative treatments, severe pain and joint instability. Severe pain levels between 4 and 8 in visual analog pain scale (VAS) scores have been reported in the postoperative period. Multimodal analgesia is considered to be the best option for pain control after total knee arthroplasty. Multimodal analgesia is defined as the combined use of different analgesia techniques such as neuraxial analgesia, peripheral nerve blocks, patient-controlled analgesia and different analgesic drugs. For this purpose, peripheral nerve blocks are effectively applied as a component of multimodal analgesia. Thus, side effects such as nausea, vomiting, pruritus and sedation that may occur due to opioid use are reduced. At the same time, in addition to providing effective analgesia, peripheral blocks contribute to early initiation of rehabilitation of the knee joint, early ambulation, reduction of pulmonary complications and early discharge from the hospital.

Recently, objective methods such as skin vasomotor reflex analysis, pupilometry, pulse plethysmographic signals and analgesia nociceptive index (ANI) have been used to standardize the need for intraoperative analgesia in patients under general anesthesia. Among these methods, ANI is a non-invasive method that provides continuous measurement of parasympathetic tone, which is a part of the autonomic nervous system. Electrodes are placed on the chest wall on both sides of the heart and the patient is monitored.

The investigators aimed to compare the analgesia nociception index (ANI) and the conventional method to determine perioperative analgesic needs in patients undergoing total knee arthroplasty under general anesthesia with femoral nerve block.