Effect of Different Doses of Esketamine on the Propofol Effect-Site Concentration Required to Suppress Cervical Dilation-Associated Movement During Hysteroscopy: A Prospective, Randomised, Controlled, Parallel-Group Dose-Response Trial.

BACKGROUND

Operative hysteroscopy is commonly performed under propofol-based intravenous anesthesia, but the relatively high propofol requirement needed to suppress movement during cervical dilation may increase the risk of respiratory and hemodynamic adverse events. Esketamine, the active enantiomer of ketamine, has greater analgesic potency and has been increasingly used as a propofol adjunct; however, its dose-dependent effects on propofol effect-site concentration during hysteroscopy remain unclear.

OBJECTIVE

To determine whether esketamine dose-dependently reduces the propofol effect-site concentration required to suppress movement during cervical dilation in operative hysteroscopy.

METHODS

In this randomised, double-blind, parallel-group dose-response trial, 112 adult women undergoing elective operative hysteroscopy were allocated across five parallel esketamine dose groups (0, 0.1, 0.2, 0.3, or 0.4 mg·kg-1) before anesthesia induction. Propofol was administered using target-controlled infusion, and the effect-site concentration was adjusted using a modified Dixon up-and-down method to estimate the median effective concentration (EC50) for suppressing movement during cervical dilation. Secondary outcomes included total propofol consumption, recovery characteristics, and perioperative adverse events.

RESULTS

Esketamine reduced the propofol effect-site EC50 in a dose-dependent manner, from 3.70 μg·mL-1 in the control group to 2.01 μg·mL-1 in the 0.4 mg·kg-1 group. Esketamine doses of 0.2-0.4 mg·kg-1 significantly reduced total propofol consumption and decreased the incidences of hypoxemia and hypotension compared with propofol alone. Higher esketamine doses were associated with more transient tachycardia. Recovery time was not clinically prolonged across groups.

CONCLUSION

Esketamine dose-dependently reduced the propofol effect-site concentration required to suppress movement during cervical dilation. In relatively healthy women undergoing short operative hysteroscopy, esketamine 0.2-0.3 mg·kg-1 appears to provide a favorable balance between propofol-sparing efficacy and cardiovascular stability.