Impact of fentanyl on acute and chronic pain and its side effects when used with epidural analgesia after thoracic surgery in multimodal analgesia: a retrospective cohort study

BACKGROUND We investigated the effects adding opioids to epidural anesthesia on acute and chronic pain and its side effects in multimodal analgesia. METHODS Retrospective cohort study. We retrospectively studied patients who received epidural anesthesia after thoracic surgery. Patients were divided into two groups: epidural anesthesia with fentanyl (group F) and without fentanyl (group N). Pain visual analog scale (VAS) scores at rest and after movement, use of nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen, side effects (nausea, vomiting, pruritus, hypotension, urinary retention), and post-thoracotomy pain syndrome (PTPS) were compared between the two groups. A Mann-Whitney U test and chi-squared test were used for statistical analysis, with significance set at P<0.05. Values were presented as median [interquartile range]. RESULTS A total of 282 patients received epidural anesthesia, 142 in group F and 140 in group N. Resting pain and movement pain were lower in group F than those in group N {resting pain: group F 12 [0-29], group N 20.5 [7-38.5], P=0.01; movement pain, group F 43 [17-65]; group N, 51.5 [39-72]; P<0.001}. Incidence of hypotension was 9.9% in group F and 2.1% in group N (P=0.01), and that of pruritus was 41.5% in group F and 10.7% in group N (P<0.001). There is no difference in the incidence of nausea and vomiting and PTPS. CONCLUSIONS In multimodal analgesia management after thoracic surgery, the addition of fentanyl to epidural anesthesia reduced acute pain and increased the incidence of hypotension and pruritus but did not affect that of PTPS.