Determination of TOF Test Threshold for Obtaining Reliable Pedicle Screw Stimulation Test During Lumbar Spine Surgery

Both Rocuronium Bromide and Cisatracurium Besylate are administered intravenously following induction of anesthesia initially by bolus, and subsequently re-bolused or administered in continuous infusion as clinically indicated to maintain muscle relaxation. Initial doses of Rocuronium range from 0.45 to 1.2 mg/kg IV, and doses for continuous infusion range from 0.01-0.012 mg/kg/min IV. Initial doses of Cisatracurium range from 0.15 to 0.2 mg/kg, and doses for continuous infusion range from 0.5 to 3 µg/kg/min. Following recovery and baseline screw stimulation at TOF \>0.9, the dosing regimen for this study will rely on restarting a continuous infusion, and adjusting the infusion until the desired TOF ratios are reached. Following screw stimulations and data collection, the infusion will be terminated, and neuromuscular blockade allowed to recover.