To evaluate the effect of opioid-free anesthesia (OFA) under the guidance of analgesia-nociception index (ANI) on the postoperative recovery quality of patients undergoing laparoscopic thyroid surgery.

A total of 120 female patients aged 18-65 years, with BMI of 18.5-28 kg/m² and ASA grade Ⅰ-Ⅱ, who underwent elective endoscopic thyroid surgery at Changde Hospital, Xiangya School of Medine, Central South University from March to December 2023 were selected. They were divided into OFA group and control group (C group) using a random number table method, with 60 cases in each group. The OFA group was induced by anesthesia with esketamine, dexmedetomidine, propofol, and rocuronium bromide, while esketamine, dexmedetomidine, and propofol were maintained; Group C was induced with sufentanil, propofol, and rocuronium bromide, while maintained with remifentanil and propofol. The dosage of anesthetic drugs was adjusted based on the bispectral index (BIS) and ANI, maintaining BIS 40-60 and ANI 50-70. The 15-item quality of recovery (QoR-15) was used to evaluate the patients’ recovery quality 1 day before (D_-1) and 1 day after surgery (D₁). The following data were recorded of HR, MAP, SpO₂, BIS, and ANI before anesthesia induction (T₀), before tracheal intubation (T₁), immediately after tracheal intubation (T₂), at skin incision (T₃), immediately after tracheal intubation (T₄), and 10 minutes after tracheal intubation (T₅). The surgical time, extubation time, recovery room stay time, first postoperative anal exhaust time, first postoperative out-of-bed activity time, and postoperative hospitalization stay were recorded. The numeric rating scale (NRS) scores at the 2nd, 6th, and 24th hour after surgery, the occurrence of perioperative adverse reactions (bradycardia, hypotension, nausea and vomiting, dizziness) and patient satisfaction were recorded.

Compared with D_-1, both groups of patients showed a decrease in QoR-15 scores on D₁ (P<0.05). Compared with Group C, the OFA group had a higher QoR-15 score on D₁ (QoR-15 total score: t=17.503, P<0.001), earlier first postoperative anal exhaust time, earlier first postoperative out-of-bed time, lower incidence of postoperative nausea and vomiting, and higher patient satisfaction (all P<0.05). HR was faster at T_1-3, MAP was higher at T_1-3 (all P<0.05). SpO₂ was lower at T₄, higher at T₅. BIS was higher at T_1-3. ANI was lower at T_1-3, higher at T_4-5. There were no statistically significant differences in surgical time, extubation time, recovery room stay time, postoperative hospitalization time, postoperative NRS pain scores at the 2nd, 6th, and 24th hour and the incidence of other perioperative adverse reactions between the two groups of patients.

OFA can advance the first anal exhaust time and ambulation time, reduce the incidence of postoperative nausea and vomiting, and improve the quality of postoperative recovery in patients after laparoscopic thyroid surgery.