Ciprofol and Remimazolam for Intraoperative Neurophysiological Monitoring During Spine Surgery (CIRIONM)

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

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Anesthesia; Spine Surgery; Intraoperative Neurophysiological Monitoring
• Intervention / Treatment: Drug: Ciprofol; Drug: Remimazolam

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.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Phase 4

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

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

Exclusion Criteria:

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Ciprofol-Remimazolam Sequence; Participants assigned to this sequence will receive ciprofol-based total intravenous anesthesia during the first stable intraoperative monitoring period. After the predefined first-period MEP and SEP recordings are completed, the hypnotic agent will be switched to remimazolam. After an approximately 45- to 60-minute stabilization and washout period, second-period MEP and SEP recordings will be obtained under remimazolam-based anesthesia. Remifentanil analgesia and standard physiologic targets will be maintained as consistently as clinically feasible across both periods.	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.
Experimental: Remimazolam-Ciprofol Sequence; Participants assigned to this sequence will receive remimazolam-based total intravenous anesthesia during the first stable intraoperative monitoring period. After the predefined first-period MEP and SEP recordings are completed, the hypnotic agent will be switched to ciprofol. After an approximately 45- to 60-minute stabilization and washout period, second-period MEP and SEP recordings will be obtained under ciprofol-based anesthesia. Remifentanil analgesia and standard physiologic targets will be maintained as consistently as clinically feasible across both periods.	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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Within-participant difference in lower-extremity MEP peak-to-peak amplitude between ciprofol and remimazolam periods	Lower-extremity target-muscle motor evoked potential peak-to-peak amplitudes will be recorded during stable intraoperative monitoring windows under ciprofol and remimazolam. The primary analysis will compare log-transformed MEP amplitude or amplitude ratio between the two drug periods within the same participant.	During surgery, at predefined stable monitoring windows under each study drug; up to 6 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Within-participant difference in lower-extremity SEP amplitude	Lower-extremity somatosensory evoked potential amplitudes will be compared between the ciprofol and remimazolam periods.	During surgery, at predefined stable monitoring windows under each study drug; up to 6 hours

Collaborators and Investigators

• Sponsor: Affiliated 2 Hospital of Nantong University

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): January 1, 2027

Study Registration Dates

• First Submitted: July 17, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 21, 2026

Study Record Updates

• Last Update Posted (Actual): July 21, 2026
• Last Update Submitted That Met QC Criteria: July 17, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Somatosensory evoked potential; Ciprofol; Spine surgery; Remimazolam; Total intravenous anesthesia; Crossover trial; Intraoperative neurophysiological monitoring; Motor evoked potential
• Additional Relevant MeSH Terms: remimazolam; (2-(1R)-1-cyclopropyl)ethyl-6-isopropyl-phenol
• Other Study ID Numbers: 2026-KT253

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No