SUMMARY OF THE PROTOCOL 

Hemodynamic responses to laryngoscopy and tracheal intubation are concerning, as adverse cardiovascular events may develop in patients with and without cardiovascular disease. Videolaryngoscopes minimize oropharyngolaryngeal stimulation during laryngoscopy and hence might attenuate this stress response.  Previous studies have shown that tracheal intubation using Truview EVO2 and McGrath^® blade provided improved laryngeal view as compared to Macintosh blade.

We aim to do a prospective randomized controlled study to see if hemodynamic responses can be attenuated with the use of videolaryngoscopes.  After approval from our institutional ethics committee and obtaining written preoperative informed consent, sixty adult patients , undergoing elective CABG, will be randomly allocated using computer generated random numbers to either MC (MacIntosh) group (n = 20), MG (McGrath^®) group (n = 20) or TV(Truview PCD^TM) group (n=20) for orotracheal tube placement using direct laryngoscopy by a number 3 or 4 Macintosh blade, McGrath^® or a Truview PCD^TM videolaryngoscope,  respectively.  Cases where intubation will not be successful despite three attempts will be excluded from the trial.

5-lead ECG for heart rate (HR)and ST segment analysis, invasive systemic arterial pressures (SBP,DBP,MAP), diastolic and mean pulmonary arterial pressures (PADP, MPAP), central venous pressure (CVP),cardiac output (CO), systemic  vascular resistance index (SVRI), pulmonary vascular resistance index (PVRI), pulse oximetry, end tidal capnography, nasopharyngeal temperature monitoring and arterial blood gas analysis will be performed in all patients. Hemodynamic changes, laryngoscopic grade, number of attempts, the time required for laryngoscopy and tracheal intubation and intra/post-operative complications will be recorded. Glottic view will be evaluated using modified Cormack and Lehane Scoring System (mC-L) and percentage of glottis opening (POGO) score. Three attempts at intubation will be allowed for all groups. Intubation difficulty score will also be assessed. Failure to intubate will be defined as inability to intubate after three attempts. An alternative technique will be used in cases of failure as per the discretion of the anesthesiologist. The duration of each attempt will also be recorded. Glyceryltrinitrate (NTG) at a dose of 1μg/kg iv will be instituted whenever the SBP increases by ≥ 20% of baseline or is persistently ≥160  mm Hg for a minute, whichever is higher. Total requirement of NTG will also be assessed. Patients will be evaluated at 24 hours after intubation for any throat pain or sore throat.