Is Intraoperative Remifentanil Associated With Acute or Chronic Postoperative Pain After Prolonged Surgery? An Update of the Literature

OBJECTIVE:: Remifentanil is an ultra-short-acting opioid that is used commonly during both short-term and prolonged surgery. This review investigated associations of intraoperative remifentanil administration with acute postoperative pain, hyperalgesia, and chronic postoperative pain, with emphasis on the perioperative coanesthetic drug regimen used. METHODS:: Medline and Embase databases were searched for randomized studies, evaluating the intraoperative use of remifentanil (>2▒h) versus another analgesic or a different dosage of remifentanil, and reporting acute postoperative pain parameters such as postoperative pain scores, hyperalgesia, acute opioid tolerance, or analgesics requirements. Furthermore, all studies in which remifentanil was used intraoperatively and parameters for chronic postoperative pain were measured were included (pain levels after a prolonged period of time after surgery). RESULTS:: From the 21 studies that were identified, less than half of the studies found higher acute postoperative pain and/or higher postoperative analgesic requirements after intraoperative remifentanil use. Coanesthetics to some extent determined this incidence, with mainly studies using volatile agents reporting increased pain levels. There was less evidence when remifentanil was combined with total intravenous anesthesia or a combination of anesthetics. The limited number of studies (n=4) evaluating chronic pain suggested a potential association with the intraoperative use of remifentanil. DISCUSSION:: Although studies are diverse and sample sizes small, coanesthetics used in combination with remifentanil may influence the occurrence of postoperative hyperalgesia. No firm conclusions could be made regarding acute and chronic pain, indicating that further research with the goal to investigate the effect of volatile or intravenous anesthetics along with simultaneous remifentanil infusion on acute and chronic postoperative pain is needed