RATIONALE: Laryngoscopic and intubation response, though transient, can have profound adverse effects. There has been a never ending quest amongst anaesthetists to find an ideal drug to attenuate the same. This study aims to find the optimal drug and dose to prevent laryngoscopic response while producing least side effects.

TITLE: Comparative assessment of two different doses of dexmedetomidine with magnesium sulphate for attenuation of the pressor response to laryngoscopy and intubation by assessment of hemodynamic parameters and plasma cortisol levels under Bi Spectral index guided anaesthesia - A randomized controlled study

OBJECTIVES:  

Primary objective:  To study and compare the Heart rate (HR) and systolic blood pressure (SBP), after administration of the study drug according to group allocation at different time intervals, maintaining Bispectral Index (BIS) values between 40-60.

Secondary objectives:

To study and compare the change in- 

1. Serum cortisol values obtained at baseline and at 3 minutes following endotracheal intubation in all the three study groups.

2. Diastolic blood pressure (DBP) at various time intervals in all the three study  groups            

3. Mean blood pressure (MBP) at various time intervals in all the three study groups

METHODS: This prospective, randomized, double blind study will be conducted in the Department Of Anaesthesiology and Critical Care, UCMS and GTB Hospital from June 2024 to June 2025 after approval by the Hospital Ethics committee. 114 consenting adult patients aged 18-65 years of age of either sex, ASA Grade I & II undergoing elective surgery under general anesthesia with endotracheal intubation will be included in this sudy. Patients will be allocated in three different groups (38 patients in each group). Prior to induction of anaesthesia, an infusion of dexmeditomidine 0.75μg/kg or 1μg/kg or magnesium sulphate 30mg/kg will be initiated according to the group that the patient is allocated. Induction of anaesthesia will be performed using standard anaesthesia techniques and laryngoscopic response using hemodynamic parameters and serum cortisol levels will be compared in the groups at various specified time intervals.

SAMPLE SIZE AND STATISTICAL ANALYSIS: Sample size was calculated using a previous study by Mahajan et al who compared dexmeditomidine and MgSO4 with normal saline as the control group. Systolic blood pressure was taken as the primary parameter for sample size calculation. Sample size was calculated using G power software using MANOVA (Multivariate Analysis Of Variance) test. The estimates used were: alpha = 5%, power = 90% and effect size of 0.25 (calculated using G power, assuming conservative estimate of eta squared = 0.06). Each group will have 38 patients with a total sample size of 114.