This was a parallel-group, randomized, double-blind, controlled trial. Ethical approval for this study (HEC-KYJJ-2021-145-01) was provided by the Institutional Review Board of Yichang Central People’s Hospital, Wujiagang District, Yichang City, Hubei Province (contact: Yan Kejun) on January 7, 2022. The trial was registered on January 15, 2022 in the Chinese Clinical Trial Registry (http://www.chictr.org.cn/showprojen.aspx?proj=149386), registration number ChiCTR2200055623. The study was conducted from January 25 to April 30, 2022 at Yichang Central People’s Hospital. All patients provided written informed consent. The patients were randomly assigned to two groups in a 1:1 ratio by computer-generated randomization. One anesthesiologist, who was blinded to the study, generated the random allocation sequence and assigned each patient a patient code.

We included female patients (age: 18–65 years, American Society of Anesthesiologists Physical Status Class I–II) scheduled for elective hysteroscopy. Patients were divided into two groups: Group S, who received general anesthesia (sufentanil, Yichang Renfu Pharmaceutical Co. LTD, Yichang city, China) and Group L, who received OFA (lidocaine, Anhui Changjiang Pharmaceutical Co. LTD, Wuhu City, China). The exclusion criteria were as follows: history of drug abuse, refusal to provide consent, history of psychotropic medication or psychological disorders, treatment using angiotensin-converting enzyme inhibitors, gastro-esophageal reflux, morbid obesity (BMI ≥ 30 kg/m2 ), allergy to any of the study drugs, use of medications or nutraceuticals that affect blood pressure (BP) or heart rate (HR), surgical procedure exceeding one hour in duration, unexpected bleeding complications, or repeated laryngeal mask airway insertion attempts.

Preoperatively, all patients fasted for 8 h and were asked to avoid oral intake of clear fluids for 2 h. Upon entry into the operating room, non-invasive BP, HR, and pulse oxygen saturation were measured, and electrocardiography was performed using a multifunctional monitor (GE Healthcare, Chicago, IL, USA), with 5 min of stabilization after each measurement. A 24-gauge intravenous catheter was subsequently placed into a vein on the dorsum of the hand.

After preoxygenation, either 1.5 mg kg− 1 lidocaine or 0.3 µg kg− 1 sufentanil was injected intravenously over a 3 s period with activation of the pump, followed by either 1.5 mg kg− 1 h− 1 lidocaine or 0.9% saline, respectively, at the same rate and volume. The anesthetic nurse who prepared the research treatment solutions and activated the pump was blinded to the study groups. Two minutes after activation, general anesthesia was standardized with 2.0 mg kg− 1 propofol (Fresenius Kabi Deutschland GmbH, Homburg, Germany) and 1 mg kg− 1 scoline (Xi’an Hanfeng Pharmaceutical Co. LTD, Xi’an City, China). If the patient exhibited no eyelash reflex, an appropriately sized laryngeal mask airway was selected using standard guidelines and the patient was intubated. After intubation without complications, 0.3 mg kg− 1 of rocuronium (Zhejiang Xianju Pharmaceutical Co., Ltd., Taizhou City, China) was administered to maintain muscle relaxation. Anesthesia was maintained using 2–3% sevoflurane (Maruishi Pharmaceutical Co., Ltd., Osaka, Japan) and 50% oxygen.

At the end of the surgery, sevoflurane and the infusions were discontinued. Patients were administered 0.04 mg kg− 1 neostigmine (Zhejiang Xianju Pharmaceutical Co., Ltd., Taizhou City, China) and 0.02 mg kg− 1 atropine (Suicheng Pharmaceutical Co., LTD, Xinzheng City, China) to antagonize any residual neuromuscular blockade, after evaluation with a neuromuscular monitor. During anesthesia, an anesthesiologist blinded to the group assignments oversaw patients’ emergence from anesthesia and graded their postoperative pain. Oral suction was performed immediately after surgery, with the patient still under anesthesia. Extubation was performed when the patient regained consciousness, with confirmation of adequate tidal volume, a regular spontaneous respiratory pattern, and purposeful behavior (eye opening upon request). After extubation, patients were monitored for ≥ 5 min to ensure regular spontaneous respiration, and were subsequently transferred to the post-anesthesia care unit (PACU). Here, patients were monitored with electrocardiography, peripheral pulse oximetry, and non-invasive BP measurements.

Patients were discharged from the PACU when their Steward score reached > 4. Other operative care was provided according to usual clinical practice. Postoperative quality of recovery was investigated using the QoR-40 questionnaire. Postoperative pain was quantified using a 100-mm visual analog scale (VAS), marked from “no pain” to “severe pain.” [9]. If the VAS score was ≥ 30/100 at rest, the attending PACU nurse administered 30 mg kg− 1 of intravenous propacetamol. The QoR-40 questionnaire was performed in the ward 24 h postoperatively by an anesthetist that was blinded to the study.

The primary outcome was the quality of recovery 24 h postoperatively as assessed using the QoR-40 questionnaire.

Secondary outcomes included the incidence of postoperative nausea and vomiting (PONV), and time to extubation. Safety-related outcomes included intraoperative respiratory/cardiovascular complications (laryngospasm, postoperative hypoxemia,arrhythmia) and rescue methods.

The sample size was calculated based on the results of our preliminary experiments and an expected QoR-40 score difference of 10 with 95% power (α = 0.05 and β = 0.1), which indicated that 40 patients were required per group. The QoR-40 scores, patient characteristics (age, height, weight, and body mass index), surgery duration, time to extubation, and time to recovery are expressed as the mean ± standard deviation, and analyzed using student’s t test. The incidence of PONV was expressed as ratio using the chi-square or Fisher exact test; P < 0.05 indicated statistical significance. Statistical analyses were performed using GraphPad Prism 8.4.3 (GraphPad Software Inc., San Diego, CA, USA).

The data associated with the paper are not publicly available but are available from the corresponding author on reasonable request.