Preoperative versus postoperative ultrasound-guided rectus sheath block for improving pain, sleep quality and cytokine levels in patients with open midline incisions undergoing transabdominal gynecological surgery: a randomized-controlled trial

BACKGROUND: Nerve block is usually performed before surgery because it inhibits reflection of the skin incision and reduces the amount of intraoperative anesthetic used. We hypothesized that performing rectus sheath block (RSB) after surgery would result in a longer duration of the analgesic effects and have a subtle influence on sleep time after surgery but that it would not decrease the perioperative cytokine levels of patients undergoing gynecological surgery. METHODS: A randomized, double-blinded, controlled trial was conducted from October 2015 to June 2016. Seventy-seven patients undergoing elective transabdominal gynecological surgery were randomly assigned to the following two groups: a general anesthesia group who received 0.5% ropivacaine hydrochloride RSB preoperatively and saline RSB postoperatively, and another group who received the opposite sequence. The objective of the trial was to evaluate the postoperative pain, sleep and changes in cytokine levels of patients during the postoperative 48 h. RESULTS: A total of 61 female patients (mean age: 50 years; range: 24–65 years) were included in the final study sample. There was no significant difference in the pain, consumption of oxycodone, or time to first administration of patient-controlled intravenous analgesia between the two groups. The postoperative sleep stages N2 and N3 were increased by 52.9 and 29.1 min per patient, respectively, in the preoperative RSB group compared with those in the postoperative group. The preoperative IL-6 concentration in the preoperative RSB group was lower than that in the same group at the end of surgery and 24 h postoperatively. CONCLUSIONS: We concluded that preoperative RSB might preserve postoperative sleep by inhibiting the increase of IL-6 without shortening the analgesia time compared with postoperative RSB in female patients undergoing elective midline incision transabdominal gynecological surgery. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02477098, registered on 15 June 2015.