To investigate the effects of sub-anesthetic doses of esketamine on cerebral oxygenation and hemodynamics in elderly patients undergoing hip arthroplasty.

Sixty patients ( age ≥ 65 years and ASA classification Ⅱ to Ⅲ) for elective hip arthroplasty were selected and randomly divided into 2 groups of 30 patients each.Anesthesia was induced and maintained essentially in the same way in the two groups, with the addition of esketamine 0.5 mg·kg^-1 intravenously at the time of induction followed by continuous pumping with esketamine 0.25 mg·kg^-1·h^-1 in the experimental group, and an equal amount of sodium chloride injection given at the corresponding time point in the control group. The mean arterial pressure (MAP), heart rate (HR), surgical volume index (SPI), and regional cerebral oxygen saturation (rSO₂) were collected at the patient’s admission to the operating room (T₀), 3 min after the procedure of induction (T₁), intubation were immediately applied (T₂), 10 min after induction (T₃), skin incision (T₄) and 1 h after surgery (T₅). The intraoperative drug use and recovery quality during awakening were observed.

Compared with that at T₀, MAP (except T₄ in the experimental group) and SPI was significantly lower (P<0.05) and rSO₂ was significantly higher (P<0.05) at all time points from T₁ to T₅ in the two groups. Compared with the control group, MAP was significantly increased at T₁, T₂, T₃ in the experimental group (P<0.05). There was no significant difference in SPI, HR, and rSO₂ between the two groups from T₁ to T₅ (P>0.05). The intraoperative usage rates of atropine and ephedrine, and the dosages of propofol and remifentanil in the experimental group were significantly lower than those in the control group (P<0.05).There was no significant difference in postoperative eye opening time and extubation time between the two groups (P>0.05).

The sub-anesthetic doses of esketamine has no significant effect on the rSO₂ in elderly patients undergoing hip arthroplasty, which can provide more stable hemodynamics for patients undergoing anesthesia, and help maintain the balance between supply and demand of oxygen in brain tissue during perioperative period.