The relationship between the level of μ-opioid receptor (μORs) and postoperative analgesic use in patients undergoing septoplasty: A prospective randomized controlled trial.
Abstract Background: In this study, the μ-Opioid receptor activity was assessed pre-operatively for its association with postoperative pain level and second analgesic requirement in patients undergoing septoplasty. Methods: In our prospective study, 120 adult patients underwent septoplasty from June 2015 to January 2019 were randomly divided into 2 pre-operative groups. The first group (n=60) was patients given tramadol (1-2 mg/kg) for post-operative analgesia, and the second group (control group) (n=60) was initially prescribed only fentanyl (1 µg/ kg-i.v.) in the induction. Acetaminophen with codeine analgesic 325/30 mg (p.o.) was used as an rescue painkiller in the post-operative period. The μ-Opioid receptor activity was investigated in pre-operative blood samples and compared to post-operative pain level and time required for second round of analgesic administration. The visual analogue score (VAS) was used to evaluate the post-operative pain degree (0 no pain; 10 worst pain). The patients’ post-operative VAS scores were evaluated upon arrival to recovery room, and at the 1st, 3rd, 7th, 10th, and 24th hour post-operative period. Results: Demographic data and peri-operative variables was similar in both study group (p<0.05).There was no significant difference between the receptor levels in both groups and the mean receptor level was 200.94±15.34 pg/Ml (max:489.92±22.36 pg/mL, min: 94.56±11.23 pg/mL).In patients who used tramadol as the levels of μ-Opioid receptors increased, VAS scores of patients and second analgesic use decreased in post-operative period.The VAS scores in patients with higher receptor levels were lower in the recovery room, (p<0.05), 1st (p<0.05) and 3rd hours (p<0.05).The VAS scores were lower in the tramadol group compared to the control group p <0.05.Number of secondary analgesic requirement was significantly lower in patients of the tramadol group with higher receptor levels compared to the ones with lower receptor (p<0.05) for arrival at the recovery room and 1st hour.Patients in the tramadol group needed a second pain killer much later than patients in the control group.Conclusions: Our study demonstrates that patients with higher μOR levels have a higher efficacy of opioid analgesic agents and an lesser need for additional analgesic agents. Trial registration:This trial was registered retrospectively (The ACTRN: ACTRN12619001652167, registration date: 26/11/2019).