A COMPARATIVE CROSSOVER RANDOMIZED STUDY OF MILLERS AND MACINTOSH BLADE FOR LARYNGOSCOPIC VIEW AND EASE OF INTUBATING CONDITIONS IN ADULTS.

After obtaining institutional ethics committee approval and patients informed consent,patient aged between 18- 65 years, satisfying the inclusion criteria will be enrolled to the study. Patients will be randomized into 2 groups by computer generated random numbers as,

v  Group MAC/MIL  and

v  Group  MIL/MAC.

Following a pre-operative evaluation patients will be kept nil per orally for 6 hours for solids and 3 hours for clear fluids, tablet Ranitidine 150 mg and tablet Ondensetron 4 mg orally with a small sip of water on the morning of surgery. Intravenous access will be secured by IV  cannulation and patient shifted to operation theatre.

Standard monitors likeelectrocardiogram(ECG) lead II, oxygen saturation (SpO2), non-invasive blood pressure (NIBP) will be attached.  Airway assessment once again will be carried out using Mallampatti classification.

The patient will be put in neutral position.The patient will be pre-oxygenated with 100% oxygen for 3 minutes. Anaesthesia will be  induced with 2 mg/ kg of propofol, fentanyl 2 µg/ kg. Feasibility of ventilation with a face mask will be checked prior to injection of  muscle relaxant. After ventilation was confirmed, inj. Atracurrium 0.5mg/kg  willbeadministered and the patient will be ventilated with Iso-flurane 0.5-1% till TOF 0/1.

In the MAC/ MIL group, initial laryngoscopic grading with a Macintosh blade will be noted and then with the Miller blade and vice versa in the MIL/ MAC group. The Macintosh blade will be advanced along the right surface of the tongue and the Miller blade will be advanced along the central surface of the tongue, the tips of both blades being placed in the vallecula. Cook’s modification of CORMACK and LEAHANE grading of the laryngoscopic views will be noted. Optimal external laryngeal manipulation (OELM) will be performed by the laryngoscopist if the grading2a or more and an improvement in laryngoscopic grading will be noted. Following each laryngoscopic attempt, an adequate depth of anaesthesia will be maintained. The patients will be intubated after the second laryngoscopic attempt irrespective of the type of blade. Ease of intubation will be graded as follows,

Ease of intubation grading:

Grade I: Intubation easy

Grade II: Intubation requiring an increased anterior lifting force and assistance to pull the right corner of the mouth upwards to increase space.

Grade III: Intubation requiring multiple attempts

Grade IV: Failure to intubate with assigned laryngoscope .

Visualization of laryngeal inlet (modified CORMACK and LEHANE Grading)

Grade 1: (full view of the vocal cords)

Grade 2A: (partial view of the vocal cords),

Grade 2B: (only the arytenoids and epiglottis seen),

Grade 3: (only epiglottis visible) and

Grade 4: (neither the epiglottis nor glottis seen).

Haemodynamical changes in the patient like NIBP, MAP, SPO2, heart rate, will be documented before induction of anaesthesia, after Induction of anesthesia but before first laryngoscopy,after first laryngoscopy, after second laryngoscopy and 5,10 and 15 minutes after intubation.

Time required for laryngoscopy to view glottis is noted with each blade. The time will begin from insertion of the laryngoscope into the mouth till first glottis view is obtained,

At the end of surgery all patients will receive inj.Ondensteron 4 mg for prevention of post-operative nausea and vomiting, Residual neuro-muscular blockade will be antagonized by inj. Neostigmine 0.05 mg/ kg and inj. Glycopyrrolate 0.01 mg/ kg and extubated once extubation criteria is met.