Ciprofol and Remimazolam for Intraoperative Neurophysiological Monitoring During Spine Surgery

Official title

Effects of Alternating Ciprofol and Remimazolam on Intraoperative Motor and Somatosensory Evoked Potentials During Spine Surgery: A Randomized Crossover Trial

Overview

Intraoperative neurophysiological monitoring, including motor evoked potentials and somatosensory evoked potentials, is commonly used during spine surgery to help detect impending neurological injury. The quality of these signals can be affected by anesthetic agents. Ciprofol and remimazolam are newer intravenous hypnotic agents that may be suitable for total intravenous anesthesia during procedures requiring neurophysiological monitoring, but direct within-patient comparisons between the two agents are lacking. This single-center, prospective, randomized, two-sequence crossover trial will compare the effects of ciprofol and remimazolam, administered with remifentanil, on intraoperative MEP and SEP signal quality during spine surgery. Eligible participants will be randomized to receive either ciprofol followed by remimazolam or remimazolam followed by ciprofol during predefined stable intraoperative monitoring windows. The primary outcome is the within-participant difference in lower-extremity MEP peak-to-peak amplitude between the ciprofol and remimazolam periods. Secondary outcomes include SEP amplitude and latency, MEP latency, warning-threshold events, hemodynamic variables, rescue medication requirements, recovery characteristics, and postoperative neurological status.

Detailed description

MEP and SEP monitoring are important components of intraoperative neurophysiological monitoring during complex spine surgery. However, evoked potential amplitudes and latencies are influenced not only by neurological injury but also by anesthetic depth, hypnotic agents, opioids, blood pressure, temperature, carbon dioxide, residual neuromuscular blockade, stimulation parameters, patient positioning, and surgical stage. Total intravenous anesthesia is therefore commonly preferred when reliable MEP monitoring is required. Ciprofol is a propofol analogue acting mainly on GABAA receptors and may provide sedation or anesthesia with less circulatory depression in some settings. Remimazolam is a short-acting benzodiazepine metabolized by tissue esterases and can be antagonized by flumazenil. Existing studies have compared each drug with propofol or reported successful MEP monitoring under remimazolam, but there is no direct randomized crossover comparison of ciprofol and remimazolam during spine surgery requiring MEP and SEP monitoring. In this trial, each participant will serve as his or her own control. Participants will be randomized in a 1:1 ratio to one of two sequences: ciprofol followed by remimazolam or remimazolam followed by ciprofol. Both study periods will be conducted under remifentanil-based analgesia and similar targets for anesthetic depth, hemodynamics, ventilation, temperature, and neuromuscular recovery. MEP and SEP recordings will be obtained during stable intraoperative windows before and after drug transition. The study aims to determine whether one agent provides more favorable neurophysiological monitoring signal quality while maintaining acceptable hemodynamic stability and surgical conditions.

Interventions

• Drug Ciprofol
  Ciprofol will be administered intravenously for induction and/or maintenance according to the institutional anesthesia protocol and product labeling. A suggested maintenance range is approximately 0.8 to 1.5 mg/kg/h, adjusted according to anesthetic depth, hemodynamics, surgical conditions, and patient safety.
• Drug Remimazolam
  Remimazolam will be administered intravenously for induction and/or maintenance according to the institutional anesthesia protocol and product labeling. A suggested maintenance range is approximately 0.5 to 2 mg/kg/h or 1 to 2 mg/kg/h, adjusted according to anesthetic depth, hemodynamics, surgical conditions, body movement, and patient safety.

Primary outcome measures

• Within-participant difference in lower-extremity MEP peak-to-peak amplitude between ciprofol and remimazolam periods [Time frame: During surgery, at predefined stable monitoring windows under each study drug; up to 6 hours]

Secondary outcome measures (1)

• Within-participant difference in lower-extremity SEP amplitude [Time frame: During surgery, at predefined stable monitoring windows under each study drug; up to 6 hours]

Eligibility criteria

Inclusion criteria

• Age 18 to 75 years.
• Scheduled to undergo elective spine surgery.
• Planned intraoperative monitoring with MEP and SEP/SSEP.
• Expected surgical duration sufficient to complete two study drug periods and intraoperative monitoring windows, preferably at least 3.5 to 4 hours.
• American Society of Anesthesiologists physical status I to III.
• Able to provide written informed consent, or consent provided by a legally authorized representative where applicable.

Exclusion criteria

• Known allergy or contraindication to ciprofol, remimazolam, benzodiazepines, propofol-related formulations, opioids, or relevant excipients.
• Severe preoperative motor or sensory deficit preventing interpretable target MEP or SEP baseline recordings.
• Implanted cardiac pacemaker, skull defect, or other condition considered unsuitable for transcranial electrical stimulation.
• Severe neuromuscular disease, poorly controlled epilepsy, severe cognitive impairment, or inability to complete postoperative neurological assessment.
• Severe hepatic or renal dysfunction, severe hemodynamic instability, shock, or requirement for high-dose vasoactive medications before enrollment.
• Long-term benzodiazepine, sedative-hypnotic, antiepileptic drug use, or drug/alcohol dependence that may substantially alter anesthetic response.
• Expected need for continuous deep neuromuscular blockade during surgery, preventing valid MEP monitoring.
• Any other condition judged by the investigators to make participation unsuitable or unsafe.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Crossover

Masking

Single blind

Primary purpose

Supportive care

Study locations

Center list to be confirmed — check the primary protocol.

Identifiers

NCT: NCT07718152 · 2026-KT253

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗