Bispectral index guided attenuation of hemodynamic and arousal response to endotracheal intubation using magnesium sulfate and fentanyl. Randomized, controlled trial

Abstract

Objectives: Airway manipulations induce marked fluctuations in heart rate and blood pressure. Strict narcotic legislations limit availability of fentanyl. This study was designed to compare the attenuating effects of intravenous magnesium sulfate with fentanyl on cardiovascular and arousal response following laryngoscopy and intubation, while ensuring anesthetic depth with Bispectral index monitoring. Methods: Seventy-five female patients ASA 1 or 2, scheduled for elective surgery under general anesthesia were randomized into three groups: Group M received 40 mg/kg magnesium sulfate, Group F, 2 μg/kg fentanyl, and Group C received saline prior to induction of anesthesia. Systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), and bispectral index (BIS) were measured at various time points. Maximum change in hemodynamic parameters and arousal response were calculated (ΔSBP, ΔDBP, ΔHR, ΔBIS). Adverse effects related to study drugs were recorded. Results: There was a statistically significant increase in BP and HR following intubation in all three groups compared to prelaryngoscopy levels. ΔSBP and ΔDBP were comparable in M and F groups, but p < 0.000 when compared with control group. Following infusion of the study drug, HR increased in M group p = 0.002, while decreased in F group, p < 0.001. BIS also increased significantly after intubation compared to prelaryngoscopy levels, ΔBIS was 9.2 (SD 2.4)%, 9.9 (1.9)% in F and M groups compared to 31.8 (7.8) in group C, p < 0.000. Hypertension, although transient, occurred in 44% in control group compared to none in other groups. Conclusion: Magnesium sulfate infusion prior to anesthesia induction effectively attenuated hemodynamic and arousal response to tracheal intubation comparable to fentanyl in normotensive patients.