Clinical effects of low‐dose esketamine for anaesthesia induction in the elderly: A randomized controlled trial

Esketamine is an N-methyl-D-aspartic acid (NMDA) receptor antagonist, which has stronger sedative and analgesic effects and fewer adverse events than ketamine. The effects of low-dose esketamine on haemodynamics and postoperative quality of recovery in elderly patients have not been evaluated. To evaluate whether low-dose esketamine can be safely used for anaesthesia induction in the elderly.Eighty elderly patients were selected for unilateral total knee replacement under general anaesthesia from February 2021 to August 2021. Patients were randomly divided into two groups (n = 40): control group (C group) and esketamine group (K group). During induction of anaesthesia, the control group was intravenously injected with normal saline of equal volume, and the esketamine group was intravenously injected with 0.2-mg/kg esketamine. Both groups were induced by etomidate, sufentanil and rocuronium and maintained by combined intravenous and inhaled anaesthesia during operation.HR, SBP, DBP, MAP and BIS values were recorded before induction of anaesthesia (T0 ), immediately before endotracheal intubation (T1 ), 1min(T2 ) and 5min(T3 ) after endotracheal intubation, surgical skin incision (T4 ), 1min(T5 ) and 5min(T6 ) after surgical skin incision.Compared with the C group, SBP, DBP, MAP, HR and BIS of the K group were significantly higher at T1 -T3 (p < 0.05). There were no significant differences in SBP, DBP, MAP, HR and BIS between the two groups at T4 -T6 (p > 0.05). Compared with T0 , SBP, MAP and BIS values of the two groups at T1 -T6 were decreased (p < 0.05). DBP of the K group at T2 was not significantly different from DBP at T0 (p < 0.05), but DBP of the C group decreased from T1 to T6 (p < 0.05). Compared with T0 , HR in both groups decreased at T1 , T3 , T4 , T5 and T6 (p < 0.05). Compared with the C group, the incidence of cough in the K group was significantly lower (p < 0.05); There was no significant difference in the number of myoclonus during induction between the two groups (p > 0.05). Compared with the C group, the number of hypotension episodes in the K group during induction was much smaller (p < 0.05). There were no significant differences in the incidence of hypertension, bradycardia and tachycardia (p > 0.05). There were no significant differences in postoperative recovery quality and incidence of adverse events between the two groups (p > 0.05).Low-dose esketamine for anaesthesia induction in the elderly undergoing knee arthroplasty may better maintain the stability of haemodynamics and has no adverse effect on the quality of early recovery after operation.