Effect of intraperitoneal infusion of ropivacaine combined with dexmedetomidine in patients undergoing total laparoscopic hysterectomy: a single-center randomized double-blinded controlled trial

Ethics Committee of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University approved this study (Ref. 2020YJ164). Each participant provided informed consent.

Women who met the ASA I–II, aged 18–65 years, scheduled for elective laparoscopic hysterectomy for uterine fibroids under spinal anesthesia were enrolled. This single-center trial was conducted at Fujian Maternity and Child Health Hospital between June 2020 and April 2021. Exclusion criteria were allergy to ropivacaine, dexmedetomidine, or other anesthetics; patients with hypertension, diabetes, heart disease, or chronic pain; mental disorders and communication disorders; conversion to open surgery; severe renal and/or hepatic disease.

This was a single-center prospective, double-blind, randomized controlled trial. Patients were randomized using a computerized simple randomization scheme in a 1:1 ratio to the R and RD groups. The group sequence was concealed in sealed opaque envelopes, which were opened only after obtaining informed consent. They received either 40 ml 0.25% ropivacaine (R group) or 40 ml 0.25% ropivacaine and 1 µg/kg dexmedetomidine mixture (RD group) [12, 13]. The study drug was prepared by an anesthesiologist who was not involved in the study. The patient, attending anesthesiologists, surgeons, recovery ward nurses, data collectors, and the person who performed the final statistical analysis were all blinded to group assignment.

The two groups of patients routinely abstained from drinking and fasted before the operation. Noninvasive blood pressure, pulse frequency, peripheral oxygen saturation, end-tidal gas monitoring, electrocardiography, and the bispectral index (BIS) were monitored throughout the procedure. One peripheral iv-lines was inserted, and 200–300 ml sodium lactate Ringer’s solution was injected. Endotracheal intubation was performed after the injection of midazolam 2 mg, sufentanil 0.5 µg/kg, etomidate 0.3 mg/kg, and rocuronium 0.6 mg/kg. After intubation, the anesthesia machine was used for mechanical ventilation, VT 6–8 ml/kg, RR 10–12 times/min, I:E 1:2, oxygen flow rate 1 L/min, and P_ETCO₂ maintained at 35–45 mmHg. During the operation, intravenous anesthesia was maintained, and propofol 4–8 mg kg⁻¹ h⁻¹ and remifentanil 0.1–0.25 μg kg⁻¹ min⁻¹ were continuously pumped according to the change of MAP and HR of the patients. The BIS was maintained at 40–60. Rocuronium 10 mg was intermittently injected during the operation. Moreover, 6 mg of ephedrine was given when MAP < 60 mmHg, and 0.5 mg of atropine was given when HR < 50 times/time.

Intra-abdominal hemostasis was completed before the end of the operation, during which the R group was sprayed with 0.25% ropivacaine 40 ml, and the RD group was sprayed with 0.25% ropivacaine and 1 µg/kg dexmedetomidine mixture 40 ml under laparoscopy. The surgeon sprayed drugs through an epidural catheter, aiming to cover the whole peritoneum with the liquid. After the operation, the tracheal tube was removed after the patient resumed spontaneous breathing. Thereafter, patients were connected to a patient-controlled analgesia pump with 1 μg/kg sufentanil 0.9% normal saline (100 ml of total volume) to deliver a bolus of 5 ml above the analgesics, with continuous background infusion of 2.5 mL/h, and a lockout time of 15 min. All patients were encouraged to use this pump so that the pain was mild. The same surgeon with more than 15 years of work experience performed all operations. The nurses recorded all the signs and symptoms of systemic toxicity induced by local anesthetics.

The primary outcome was the quality of recovery, which was assessed on the day before surgery and 24 h after surgery using a 40-item questionnaire (QoR-40) [14]. The total score ranged from a minimum of 40 to 200 points, respectively, representing the worst and best recovery quality.

Secondary outcomes were postoperative NRS score, the time to the first dosage of postoperative opioid, and the cumulative number and the effective number of PCA compressions 24 h after the operation. NRS score is a numeric rating scale patients use to evaluate their pain on a scale from 0 to 10, with 0 indicating no pain and 10 indicating the worst imaginable pain. The time to ambulation, anal exhaust, and urethral catheter removal were also evaluated. The incidence of dizziness, nausea, and vomiting was also analyzed.

Our sample size calculation for the two-tailed testing was based on the global QoR-40 score. A 10-point difference represents a clinically relevant improvement in the quality of recovery based on data from a previous study [14]. A mean (standard deviation) of the QoR score at 24 h postoperative equivalent to 171 (14.6) was estimated based on our pilot study. A power analysis with a type I error estimate of 5% (alpha = 0.05), and a power (1-Beta) of 90% indicated that a sample of 46 subjects per group was required. Allowing for approximately 10% incomplete follow-up or dropout, 112 subjects were enrolled in this study.

SPSS version 18.0 was used to perform statistical analysis (SPSS Inc., Chicago, IL, USA). The normality of distribution was assessed with the Kolmogorov–Smirnov test. Parameters with normal distribution were reported as mean ± standard deviation (SD) and analyzed with the independent test, and those with non-normal distribution were reported as the median and interquartile range (IQR) and analyzed using the Mann–Whitney test. Categorical variables were reported as the number of patients (%) and evaluated using the X² or Fisher’s exact test when appropriate. A p < 0.05 was considered statistically significant.