Yanping Shen,1 Lijun Yin,1 Binnan Hu,1 Yilun Xia,1 Liangguang Zhang2 

1Department of Anesthesiology, The Affiliated Women and Children’s Hospital of Ningbo University, Ningbo, Zhejiang, People’s Republic of China; 2Department of Anesthesiology, Ningbo No.6 Hospital, Ningbo, Zhejiang, People’s Republic of China

Correspondence: Liangguang Zhang, Department of Anesthesiology, Ningbo No.6 Hospital, 1059 East Zhongshan Road, Ningbo, Zhejiang, 315040, People’s Republic of China, Email lgzhang1987@163.com

Background: Propofol injection pain (PIP) is a frequent adverse effect during anesthesia induction, impacting patient comfort and satisfaction. Esketamine has been shown to alleviate PIP, but the optimal dose, especially in relation to preoperative anxiety levels, remains unclear. Preoperative anxiety may heighten pain perception and influence analgesic requirements.
Methods: A randomized, double-blind, controlled trial was conducted at The Affiliated Women and Children’s Hospital of Ningbo University. A total of 150 eligible patients scheduled for painless abortion were assessed using the Spielberger State Anxiety Inventory - State form (STAI-S) and categorized into non-anxious (STAI-S score < 40) and anxious (STAI-S score ≥ 40) groups. Patients were randomized using a computer-generated random number table to receive one of five escalating doses of esketamine (0.10, 0.12, 0.14, 0.17, or 0.20 mg/kg) prior to propofol administration. The primary outcome was the occurrence of PIP, assessed using Ambesh’s four-point pain scale. Secondary outcomes included hemodynamic parameters and adverse events such as hypotension, bradycardia, and hypoxemia.
Results: A clear dose-response relationship was observed, with higher doses of esketamine significantly reducing the incidence of PIP in both groups. Anxious patients required higher doses of esketamine to achieve comparable pain relief to non-anxious patients. The effective dose for 50% of patients (ED50) in the non-anxious group was 0.114 mg/kg (95% CI: 0.096– 0.129 mg/kg), whereas it was 0.133 mg/kg (95% CI: 0.117– 0.146 mg/kg) in the anxious group, with the difference being statistically significant (P < 0.05). No significant differences were observed between groups in terms of adverse events or hemodynamic stability.
Conclusion: Preoperative anxiety significantly increases the ED50 of esketamine required to alleviate propofol injection pain in patients undergoing painless abortion. Anxious patients require higher doses of esketamine to achieve effective analgesia. Individualizing esketamine dosing based on preoperative anxiety levels may enhance patient comfort and optimize pain management during anesthesia.

Keywords: propofol injection pain, esketamine, preoperative anxiety, painless abortion, anesthesia, dose-response