Lidocaine versus magnesium sulfate infusion during isoflurane anesthesia for brain tumor resection, effect on minimum alveolar concentration reduction guided by bispectral index: a prospective randomized controlled trial

Objective: Goals of neuro-anesthesia include smooth induction, stable perioperative hemodynamics, early and quiet recovery with adequate analgesia. Intraoperative use of co-sedatives allows reduction of anesthetic agents consumption while maintaining a desirable depth of anesthesia. Many drugs like opioids and dexmedetomidine had been studied in different surgeries. Using such drugs enhances rapid recovery for early postoperative assessment and detection of complications.Methods: This study enrolled 50 adult patients undergoing supratentorial brain tumor surgery. Patients of the lidocaine group (group L) received 1.5 mg.kg−1 of lidocaine as a loading dose over 10 min before induction of anesthesia and followed by infusion at a rate of 1.5 mg.kg−1.h−1. Patients of the magnesium group (group M) received 30 mg.kg−1 of magnesium sulfate as a loading dose over 10 min before induction of anesthesia and followed by infusion at a rate of 10 mg.kg−1.h−1. Depth of anesthesia was guided by bispectral index in a range of 50 ± 2, with the primary outcome objective, minimum alveolar concentration reduction of inhaled isoflurane.Results: No significant difference was found regarding patient demographics, basal hemodynamic data, and anesthesia duration. The used isoflurane concentration at the matching time points (every 15 min intraoperatively) and the total dose of muscle relaxant (160 ± 15 mg, 175 ± 18 mg respectively, p 0.003) were statistically lower in group M than in group L. The time required for recovery was statistically shorter in group M than in group L (5.1 ± 0.99 min vs 9.8 ± 1.9 min, respectively, p 0.00). Conclusion: Compared to lidocaine infusion, magnesium sulfate (MgSO4) infusion during anesthesia for brain surgery resulted in lower anesthetic consumption, muscle relaxant requirement, a shorter recovery time, and a better postoperative pain profile. MgSO4 can be used effectively as a co-sedative adjuvant with superior clinical properties than lidocaine infusion.