After obtaining the approval of ethics committee and written informed consent. The study was registered with Chinese Clinical Trial Registry number: ChiCTR1900022268, which was registered in 2 April 2019, http://www.chictr.org.cn/edit.aspx. The work has been reported in line with Consolidated Standards of Reporting Trials (CONSORT) Guidelines.
80 patients undergoing elective cesarean section were recruited. The study was a randomized, placebo-controlled trial that was conducted from April to June 2019.
Inclusion criteria included ASA classⅠorⅡ women, aged 18 yr or more undergoing elective caesarean section under epidural anasthesia including epidural morphine. Exclusion criteria were as follows: no consent to study, coagulation dieases, liver or kidneyfailure, preexisting pruritus, previous surgery in the lumbar spine.
Ater arrival in the operating room, all patients received epidural anesthesia. Epidural catheterization was performed using an 18-gauge epidural needle and a epidural catheter at the T12-L1 or L1-L2 level. 0.5% ropicacaine 12ml (60mg) and morphine (3mg) were administered. Patients were placed in the supine position, and intraoperatively, systolic blood pressure was maintained above 100 mmHg by colloid liquid and intermittent injection of phenylephrine.
The patients were divided randomly into two groups: a placebo group (saline injection) and a nalmefene group(50ug nalmefene injection). The nalmefene or placebo was administered near the end of surgery, and other intraoperative anaesthetic and postoperative care were standardized in this study. Baseline date such as patient age, characteristics, operation time were collected. The incidence of intraoperative pain or nausea/vomiting was recorded. In the postoperative period, the level of pruritus, pain score, and other adverse effects included nausea and vomiting were evaluated 2, 4, 8, 12, and 24 h after nalmefene or saline administration. 24 hours after delivery, patients were reexamined to determine the total incidence of pruritus, whether treatment for pruritus or pain had been required. The severity of pruritus was assessed by verbal rating scale: 0 = no pruritus, 1 = mild pruritus, 2 = moderate pruritus, 3 = severe pruritus.3 Pain scores with VAS, range 0 and 10, with 0 = no pain and 10 = unbearable pain. Intravenous ondansteron (4mg) in the treatment of nausea and vomiting. When necessary, non-steroidal anti-inflmmatory drugs or intravenous morphine were used to assist postoperative analgesia.
Statistical analysis
Statistical analysis was performed by use of the statistical software SPSS 13.0. Power Analysis and Sample Size (PASS) software (NCSS), LLC, Kaysville, UT, USA) was used for the sample size calculation. Clinically, it is considered which has therapeutic significance to reduce the incidence of pruritus by 30%. The sample size was estimated with α = 0.05 and β = 0.95, respectively. In the preliminary study, the incidence of pruritus in the control group was 65%. Therefore, each group must include at least 32 patients for the requirement of 30% reduction of pruritus incidence.
After normality testing using Levene method, the patients’data will be presented as the mean and standard deviation (SD) if they are normally distributed; otherwise, they will be presented as the mean and interquartile range. count data groups were analyzed using chi-square test. The χ2 test and Fisher’s exact test will be used for compare proportional data, the Nemenyi test will be used to compare the difference between two groups. A P<0.05 was considered statistically significant.