Comparative effects of alfentanil-remimazolam versus fentanyl-remimazolam on anesthesia onset, emergence, and safety in first-trimester surgical abortion under intravenous anesthesia: a randomized controlled trial.

BACKGROUND

Alfentanil is a short-acting μ-opioid receptor agonist that can be used synergistically with other sedatives. This study aimed to investigate the clinical efficacy of an alfentanil-remimazolam combination for first-trimester surgical abortion (vacuum aspiration) under intravenous anesthesia.

METHODS

A total of 120 patients undergoing first-trimester surgical abortion under intravenous anesthesia at our hospital were recruited between January 1, 2025 and June 30, 2025, and were randomly assigned to two groups: the alfentanil-remimazolam group (AF-RMZ, n = 60) and the fentanyl-remimazolam group (F-RMZ, n = 60). The AF-RMZ group received alfentanil (10 μg kg-1) combined with remimazolam (0.3 mg kg-1), while the F-RMZ group received fentanyl (1 μg kg-1) combined with remimazolam (0.3 mg kg-1). The primary outcome was emergence time from anesthesia. Secondary outcomes included intravenous anesthesia induction time, total remimazolam dose, Visual Analog Scale (VAS) score at 30 min after awakening, and adverse events, including low pulse oximetry (SpO₂), bradycardia, hypotension, somatomotor response, and postoperative nausea and vomiting (PONV).

RESULTS

The AF-RMZ and F-RMZ groups had comparable demographic characteristics. AF-RMZ showed shorter induction (37.97 ± 4.38 s) and emergence times (68.40 ± 47.01 s) and reduced discharge time (36.38 ± 5.31 min) compared with F-RMZ, while total remimazolam use and postoperative 30-min VAS scores were similar. Heart rate and respiratory rate exhibited significant group-time interactions, whereas mean arterial pressure remained comparable. Peripheral oxygen saturation was transiently higher in the F-RMZ at early time points. All SpO₂ values remained clinically acceptable, supporting monitored respiratory safety. Adverse events were mild, with a lower incidence of somatomotor response in AF-RMZ (8.3% vs. 21.7%, p = 0.036).

CONCLUSION

Alfentanil combined with remimazolam showed a slight advantage in anesthesia induction and emergence times, with comparable postoperative recovery, clinically stable hemodynamics, and safety profiles compared with fentanyl-remimazolam in outpatient gynecological procedures; however, the clinical impact of these differences may be limited.

CLINICAL TRIAL REGISTRATION: https://www.chictr.org.cn, identifier ChiCTR2400094571.