Reducing Pain with Methadone and Ketamine in Liver Transplant

Pain control following liver transplantation (LT) has been the subject of interest of many research projects due to invasive nature of the procedure, significant comorbidities of recipients, effect of hepatic metabolism on many common pain medications and difficulties in performing some neuraxial and regional techniques given patient coagulopathy. Some newer regional nerve blocks such as External Oblique Intercostal (EOI) block has also been successfully utilized in pain management of patients undergoing liver resections but their utilization in perioperative setting for high-MELD patients and after-hour operations are limited. Methadone and ketamine are well-known drugs that have been recently emerged as components of new pain management pathways in many open surgeries due to their availability, cost, well-known metabolism, good safety profile and prolonged effects. Evidence has emerged that their use is associated with decreased likelihood of development of chronic pain and need for long term opioids. The combination of methadone and ketamine has been shown to be superior to opioids alone due to synergistic effect on N-methyl-d-aspartate and μ-opioid receptors. But these medications have not been extensively studied in LT recipients except for a few case reports and small studies. Current standards of care for intraoperative pain management during LT are systemic short and medium long-acting opioids such as fentanyl and hydromorphone which both have numerous concerns such as respiratory depression and opioid dependency. The aim of this study is to prospectively evaluate the effect of intraoperative methadone and ketamine administration on postoperative pain in liver transplant recipients. These drugs have been safely used during liver transplantation at LHMC and other centers and showed to be effective and safe, but the exact dosing and timing of administration requires further studies.