Effects of rocuronium dosage on intraoperative neurophysiological monitoring in patients undergoing spinal surgery.

WHAT IS KNOWN AND

OBJECTIVE

Intraoperative neurophysiological monitoring (IONM) has been widely used in clinical practice. Therefore, the influence of neuromuscular blockers essential for spinal anaesthesia on IONM is worthy of our attention, but no randomized study has evaluated the dose-response effect. This study investigated the effects of different doses of rocuronium bromide on the intraoperative monitoring of motor evoked potentials (MEPs).

METHODS

We conducted a randomized, double-blind trial to assess the effects of three rocuronium bromide doses (6.0, 9.0, 12 μg·kg-1 ·min-1 ) combined with intravenous infusion of propofol 6-8 mg·kg-1 ·h-1 and remifentanil 10 μg·kg-1 ·h-1 on the amplitudes of somatosensory evoked potentials (SEPs) and MEPs at the time of the baseline recording (T1 ), before pedicle screw placement (T2 ) and before spinal canal decompression (T3 ). Secondary outcomes included measurement of neuromuscular function, the occurrence of unexpected intraoperative body movement and recovery of spontaneous breathing.

RESULTS AND DISCUSSION: A total of 123 patients were enrolled, and 120 patients were ultimately analysed. No differences were observed in the amplitude of SEPs among the three groups (p > 0.05). The MEP amplitude differences at T1 , T2 and T3 in all limbs did not differ in patients receiving rocuronium at 6.0 μg·kg-1 ·min-1 and 9.0 μg·kg-1 ·min-1 (p > 0.05). However, when rocuronium was administered at 12.0 μg·kg-1 ·min-1 , MEP amplitudes at the time point T3 were significantly attenuated compared with the time points T1 and T2 in both right upper limb and left lower limb (p = 0.002, p = 0.025, respectively). In patients treated with rocuronium 6.0 μg·kg-1 ·min-1 , the incidence of unexpected body movement was significantly higher (p = 0.026), and the train-of-four count (TOF count) showed a significant increase at T2 and T3 (p < 0.001) compared to other doses.

WHAT IS NEW AND

CONCLUSION

Rocuronium bromide at a rate of 9.0 μg·kg-1 ·min-1 provided suitable and adequate muscle relaxation without inhibiting IONM; thus, this dose is recommended for spinal surgery.