This study was registered on April 2, 2019, and was assigned a Chinese Clinical Trial Registry number: ChiCTR1900022268
(http://www.chictr.org.cn/edit.aspx). This work has been
reported in accordance with the guidelines of the Consolidated Standards of Reporting Trials (CONSORT).
In this study, a randomized and placebo-controlled trial was performed on a total of 80 patients undergoing elective cesarean section from April of 2019 to June of 2019.
We recruited the following individuals in the study: ASA classⅠorⅡ women aged 18 years or older who were scheduled for an elective caesarean section under epidural anaesthesia. The following exclusion criteria were applied in this trial: no consent obtained for this study, coagulation dieases, liver or kidney failure, pre-existing itching, a history of lumbar spine surgery.
To perform epidural anesthesia, an 18-gauge epidural needle was used and an epidural catheter was inserted at the T12-L1 or L1-L2 level of the patients. 60 mg (12 ml) of 0.5% ropicacaine and 3 mg of morphine were then administered respectively. The patients were maintained at supine position, and maintenance of a systolic blood pressure of at least 100 mmHg throughout the operation was performed by using colloid liquid as well as intermittent injection of phenylephrine.
All patients were randomly assigned into the placebo group (injection with saline) and nalmefene group (injection with 50 ug of nalmefene). Nalmefene or placebo was administered just prior to the end of surgery, and intraoperative anaesthesia and postoperative care were routinely conducted. Baseline data of the patients, including age, characteristics, and operation time, were collected. The rate of pain or nausea/vomiting during the operation was recorded. Following the operation, the severity of itching, pain scores, and other side effects such as nausea and vomiting were evaluated 2, 4, 8, 12, and 24 h after administration of nalmefene or saline, respectively. At 24 hours following delivery, patients were reexamined to determine the total incidence of pruritus, regardless of the requirement for a treatment of pruritus or pain. The assessment of pruritus intensity was performed based on verbal rating scale (0 no pruritus, 1 mild pruritus, 2 moderate pruritus, 3 severe pruritus).3 VAS scores for pain ranged from 0 (no symptom) to 10 (unbearable pain). 4 mg of Intravenous ondansteron was administered for relieving nausea and vomiting. Non-steroidal anti-inflmmatory drugs or intravenous morphine were used to assist postoperative analgesia when necessary.
The software SPSS 13.0 was used for statistical analysis in this study. The sample size was calculated by using Power Analysis and Sample Size (PASS) software (NCSS) (LLC, UT, USA) with α=0.05 and β=0.95. Clinically, a reduction in the incidence of pruritus by 30% indicates a therapeutic significance. The preliminary analysis revealed a high incidence of pruritus (65%) in the control group. Thus, each of the groups in this study must contain no less than 32 patients in order to fulfill the requirement for a 30% reduction in the incidence of pruritus.
Levene method was used for testing normality. The normally distributed data was presented as the mean and standard deviation (SD), while the other data was presented as the mean and interquartile range. Count data groups were analyzed using chi-square test. Comparative analysis of proportional data was carried out based on the χ2 test as well as Fisher’s exact test. Nemenyi test was performed for determining the difference between the two groups. Statistically, P＜0.05 represented a significant difference.