To investigate the safety and feasibility of opioid-free anesthesia with esketaminein patients undergoing total knee arthroplasty (TKA).

A total of 202 patients aged 18 to 75 years who underwent TKA in Panzhihua Central Hospital were enrolled, with American Society of Anesthesiologists (ASA) grades Ⅱ to Ⅲ, body mass index (BMI) of 18 to 30 kg/m², and without coagulation abnormalities before surgery or history of anesthetic drug allergy. Using a computer generated random number table, patients were randomly divided into the opioid anesthesia (OA) group (n=101) and the opioid-free anesthesia (OFA) group (n=101) according to odd/even numbers. Independent samples t test, chi square test, and repeated measures analysis of variance were used to compare the two groups in terms of anesthesia-related indicators, analgesic and sedative effects, hemodynamic indicators, incidence of postoperative chronic woundpain, and incidence of adverse reactions.

Compared with the OA group, the OFA group showed significant reductions in wake-up time, time to extubation, post-anesthesia care unit (PACU) stay, time to first ambulation, and total dosage of sufentanilin 48 h after surgery (t=12.558, 15.065, 11.830, 15.126, 30.852, all P<0.05). There were statistically significant differences in the visual analogue scale (VAS) scores in resting and motion states, and Ramsay sedation scale (RSS) scores in terms of interaction, inter-group, and time effects (F=13.111, 42.860, 57.079; F=9.683, 28.574, 42.106; F=9.091, 32.258, 65.217; all P<0.05). Compared with the OA group, the OFA group had lower VAS scoresin resting state at four, six, 12, 24 and 48 h after surgery (t=32.648, 21.55, 24.448, 24.428, 29.700, all P<0.05), andlower RSS scores at 6 h and 12 h after surgery (t=11.126, 31.115; all P<0.05). There were statistically significant differences in heart rate, mean arterial pressure and bispectral index (BIS) values in terms of interaction effect (F=15.789, 98.765, 12.346; F=13.462, 78.947, 10.870; F=3.875, 43.478, 57.011; all P<0.05). Compared with the OA group, the OFA group had significantly higher heart rate, mean arterial pressure and BIS values at T1, T2, T3, and T4 (t=11.751, 10.081, 7.688, 3.108; t=14.235, 9.270, 4.612, 2.085; t=5.624, 6.857, 5.813, 6.717, all P<0.05). The incidence of chronic wound pain was significantly lower in the OFA group than in the OA group at one, three, and six months after surgery (χ²=6.931, 9.727, 15.732, all P<0.05). The incidence rates of postoperative nausea and vomiting, and respiratory depression were significantly lower in the OFA group (χ²=4.028, 6.733, all P<0.05).

Opioid-free anesthesia with esketamine can achieve good anesthetic and analgesic effects on patients undergoing TKA, with clear advantages in reducing perioperative opioid dosage, stabilizing perioperative hemodynamics, and reducing postoperative chronic pain.