This was a pilot prospective interventional study from January 2020 to October 2023. This study was approved by the ethics review committee of Fuxing Hospital, Capital Medical University (Ethics approval number: 2020FXHEC-KY036). Trial registration number: NCT03524950.

The inclusion criteria were: age 40–60 years; ASA grade 1–2; scheduled to undergo elective laparoscopic UF surgery.

The exclusion criteria were: patients with unstable cardiovascular disease; hepatic and renal insufficiency; obesity; alpha-blocker use; severe obstructive sleep apnea hypopnea syndrome (OSAHS); severe allergies, history of specific drug use; history of psycho-psychological disorders and emergency operation.

The 214 patients who received laparoscopic UF surgery in the Fuxing Hospital, Capital Medical University were randomly divided into two groups, the non-dexmedetomidine group (Group1) or the dexmedetomidine group (Group2), via a computer generated random number table. The random numbers were sealed in envelopes by a trial coordinator. The coordinator opened the envelopes to assign the treatment and prepared the study drugs according to the group assignment (the Group1: normal saline 50 mL; the Group2: dexmedetomidine, Yangzijiang Pharmaceutical Company, Taizhou, Jiangsu, China. 200 µg, diluted with normal saline to 50 mL). The coordinator was not involved in anesthesia management or data collection. All providers were blinded to the individual patient assigned group.

Before anesthesia induction, both groups were injected with the study drug pump for 10 minutes (the injection rate was 1 µg/kg/h of dexmedetomidine when calculating the pump rate). During anesthesia induction, the two groups received sufentanil 0.5 µg/kg, propofol initiated at 6 µg/mL via target-controlled infusion (TCI), and rocuronium 0.6 mg/kg. During the maintenance phase, the two groups received continuous remifentanil 0.1–0.3 µg/kg/min and propofol. The dosage of propofol was adjusted to maintain the bispectral index (BIS) at 45–55. In addition, the two groups received the study pump (the injection rate was 0.7 µg/kg/h of dexmedetomidine when calculating the pump rate). The monitor was an Infinity Vista XL (Dräger, Lubeck, Germany), and the anesthesia machine was a Fabius 2000 (Dräger, Lubeck, Germany).

The other procedures were same in both groups. The BIS value was maintained at 45–55 through adjusting the dosage of propofol. The end-expiratory carbon dioxide partial pressure was maintained at 35–45 mmHg during the operation. If the mean arterial pressure increased by 30%, urapidil hydrochloride 10–30 mg was used. Repeat administration could occur after 5–10 min. If the mean arterial pressure decreased by 30%, ephedrine hydrochloride 6–10 mg was used, with repeat after 5–10 min. There was no significant decrease in blood pressure in this study, resulting in ephedrine hydrochloride not being used.

During the operation, the surgeon performed the operation through three perforations performed in the patient’s abdomen, injecting a specific dose of pituitrin in the surgical site, and then removed the uterine fibroids. The surgeons are all senior doctors who performed laparoscopic UF surgery for over 500 patients.

Demographic information, including age, height, weight, number of the UF, size and location of the UF, were obtained from the medical records. The mean arterial pressure (MAP) and heart rate (HR) were used as the indicators of hemodynamic status at multiple time points: when entering the operating room (MAP1, HR1), immediately at the time of local pituitrin injection (MAP2, HR2), and at 5 min after injection of pituitrin (MAP3, HR3). The medications and dosages (propofol, urapidil hydrochloride, fluid) used during the operation, and the recovery (drowsiness, chills, nausea, vomiting and dysphoria) after the operation were recorded. Total mean time from the beginning of the operation to pituitrin injection (Time1) and recovery time after peak blood pressure with pituitrin injection (Time2) were recorded. Data recording was done by the anesthesiologist.

SPSS 26.0 (IBM Corp., Armonk, NY, USA) was used for statistical analysis. The continuous variables conforming to the normal distribution (Kolmogorov-Smirnov test) were presented as means $\pm$ standard deviations and analyzed using the independent sample t-test; Categorical variables were expressed in frequency (percentage) and analyzed using Chi-square tests. p-values 0.05 were considered statistically significant.

There were 214 patients in each group. Four cases of conversion to laparotomy and 2 cases of voluntary abandonment from the study were excluded. The remaining 210 patients underwent surgery successfully. Their baseline characteristics are shown in Table 1. There were no significant differences in age, height, weight, size and number of UF, and the location of uterine fibroids between the two groups (Fig. 1).

Fig. 1.

Flow chart. UF, uterine fibroids.

Table 2 presents the surgery-related data. There were no differences between the groups for MAP1, MAP2, HR1, HR2, HR3, Time1 (all p $>$ 0.05), but the dexmedetomidine group was smaller in MAP3 (p = 0.041) and Time2 (p = 0.000) than the non-dexmedetomidine group.

Table 3 presents the changes in hemodynamic index data. There were no differences between the groups for MAP2-MAP1, MAP3-MAP2, HR2-HR1, HR3-HR1, and HR3-HR2 (p $>$ 0.05). There was significant difference in MAP3-MAP1 (p = 0.025) between the two groups.

Table 4 presents the surgery-related parameters data. There were no differences between the two groups for fluid volume (p $>$ 0.05). There was significant difference in propofol (p = 0.011) and urapidil hydrochloride (p = 0.000) use between the two groups.

Table 5 presents the relevant indicators of postoperative recovery data. There were no differences between the groups for drowsiness (p $>$ 0.05). There was significant difference in chills (p = 0.002), nausea (p = 0.000), vomiting (p = 0.043), and dysphoria (p = 0.024), between the two groups.