Propofol sparing effect of dexmedetomidine and magnesium sulfate during BIS targeted anesthesia: A prospective, randomized, placebo controlled trial

BACKGROUND AND AIMS: Maintenance of adequate depth of anesthetic is crucial to prevent awareness and to reduce stress response associated with surgery. Goals of balanced general anesthetic are met by use of adjuvants to facilitate use of lower anesthetic dose, while ensuring adequate anesthetic depth. This study employed BIS monitoring to compare the anesthetic sparing effects of intravenous dexmedetomidine and magnesium sulphate on induction dose of propofol by maintaining a BIS value of 40-50. MATERIAL AND METHODS: One hundred and twenty ASA I and II patients undergoing elective surgery under general anesthetic were included in three groups of forty each. Group D received 1 μg/kg of dexmedetomidine, Group M was given 30 mg/kg of magnesium sulphate in 100 ml saline and Group N received 100 ml saline over 15-20 minutes 15 minutes before induction. Data compared were dose of propofol and vecuronium, Ramsay sedation score, BIS values and hemodynamic parameters intraoperatively. RESULTS: Propofol required in group D was significantly lower 101.3 ± 16.5 than group M and N with dose of 114 ± 15.5 and 160.50 ± 25.08 respectively (p <0.001). Dose requirement of vecuronium was significantly reduced in group M 5.4 ± 0.8 and group D 6.6 ± 1.2 as compared to N 7.9 ± 1.4 (p <0.001). No significant differences were seen regarding baseline hemodynamics, RSS and BIS values in all groups. After study drug infusion, RSS was 4.59 ± 0.75 in dexmedetomidine group compared to 1.9 ± 0.7 and 1.4 ± 0.5 in group M and N (p <0.001). During maintenance, significantly lower HR, MAP and BIS values were seen in group D and M than N (p <0.001). CONCLUSION: Our study showed that pretreatment with dexmedetomidine and magnesium sulphate significantly reduced the induction dose of propofol by maintaining a constant BIS in value at 40-50. However, both the drugs reduced the time to reach BIS 40-50 but sedation and sparing of propofol was more in dexmedetomidine group.