REMIfentanil (2 vs. 4 mcg/kg) Facilitated Intubation Without Neuromuscular Blockade Versus Succinylcholine and Rocuronium With Sugammadex for Endotracheal Intubation in Spine Surgery Requiring Motor Evoked Potential Monitoring

Excellent intubating conditions are defined as all assessed intubating condition domains rated as excellent. Domains include ease of laryngoscopy, vocal cord position and movement, and participant reaction to intubation. The outcome will be reported as the percentage of participants in each arm with excellent intubating conditions.

Successful first-attempt endotracheal intubation is defined as successful placement of the endotracheal tube on the first laryngoscopy attempt, confirmed by capnography over four respiratory cycles. The outcome will be reported as the percentage of participants in each arm with successful first-attempt intubation.

Glottic visualization will be assessed using the Cormack-Lehane grading system. Grades range from 1 to 4, with lower grades indicating better visualization of the glottis and higher grades indicating poorer visualization. The outcome will be reported by grade for each arm.

Intubation difficulty will be assessed using the Intubation Difficulty Scale. Scores range from 0 to infinity, with 0 indicating an easy intubation and scores greater than 5 indicating difficult intubation. The outcome will be reported as the Intubation Difficulty Scale score for each arm.

The number of laryngoscopy attempts required to achieve successful endotracheal intubation will be recorded. The outcome will be reported as the number of attempts for each arm.

Time to successful endotracheal intubation is defined as the elapsed time, in seconds, from administration of the assigned study drug to successful endotracheal tube placement confirmed by capnography. The outcome will be reported in seconds for each arm.

Rescue neuromuscular blockade is defined as administration of succinylcholine in participants assigned to a remifentanil arm because of poor intubating conditions or unsuccessful intubation after two attempts. The outcome will be reported as the percentage of participants in the remifentanil arms who required rescue neuromuscular blockade.

Alternative intubation technique is defined as use of an additional airway technique or device, such as a bougie or different laryngoscope blade, to facilitate endotracheal intubation. The outcome will be reported as the percentage of participants in each arm requiring an alternative intubation technique.

Participant movement during intubation will be assessed by the blinded observer and recorded as present or absent. Movement may include diaphragmatic movement, coughing, bucking, or other clinically observable movement during intubation. The outcome will be reported as the percentage of participants in each arm with movement during intubation.

Adjunct medication is defined as any additional medication administered to facilitate induction or intubation beyond the assigned study drug and standardized induction regimen. Examples may include midazolam, fentanyl, or lidocaine. The outcome will be reported as the percentage of participants in each arm requiring adjunct medication.

Mean arterial pressure will be measured using standard intraoperative monitoring. Change from baseline will be calculated as the post-induction or intubation value minus the baseline value recorded before induction of anesthesia. The outcome will be reported for each arm.

Heart rate will be measured using standard intraoperative monitoring. Change from baseline will be calculated as the post-induction or intubation value minus the baseline value recorded before induction of anesthesia. The outcome will be reported for each arm.

Hypotension, bradycardia, and oxygen desaturation occurring during induction and intubation will be recorded according to protocol-defined safety monitoring procedures. The outcome will be reported as the percentage of participants in each arm with one or more of these events.

Intubation-related complications include dental trauma, aspiration, airway trauma, or other clinically documented complications related to endotracheal intubation. The outcome will be reported as the percentage of participants in each arm with at least one intubation-related complication.

Time to baseline motor evoked potential acquisition is defined as the elapsed time, in minutes, from successful endotracheal intubation to acquisition of baseline motor evoked potential signals according to institutional neuromonitoring procedures. The outcome will be reported in minutes for each arm.

Motor evoked potential signal quality will be assessed using neuromonitoring documentation, including signal amplitude and successful detection of baseline signals. The outcome will be reported for each arm using the protocol-specified signal quality variables.

Postoperative myalgia is defined as participant-reported muscle pain after surgery, assessed at approximately 24 hours postoperatively. The outcome will be reported as the percentage of participants in each arm with postoperative myalgia at 24 hours.

Postoperative myalgia is defined as participant-reported muscle pain after surgery, assessed at approximately 48 hours postoperatively. The outcome will be reported as the percentage of participants in each arm with postoperative myalgia at 48 hours.

Postoperative opioid consumption will be obtained from the medical record and summarized using the protocol-specified opioid consumption unit or conversion method. The outcome will be reported for each arm over the postoperative assessment period.