A Comparative study of the Effects of Different Types of Laryngoscopes on the Cervical spine Motion using an inclinometer : Randomised clinical trial.

Study patients are adults undergoing elective surgery under

general anaesthesia requiring endotracheal intubation. The enrolled patients will be divided in

to four groups Group-1,2,3,4 in which patients will be intubated with mc-intosh

Laryngoscope, cmac, mcgrath, BPL respectively. Patients will be allocated to specific group

through random number generated through computer in a sealed envelopes technique.

Routine preoperative anaesthetic check up and optimization, if needed will be done.

Once patients will be taken into the operation theater, standard preinduction monitors such as

electrocardiograms, pulse oximetry, non-invasive BP monitoring.

Intravenous access will be obtained with a 18G or 20G cannula

under strict aseptic conditions .Now patient made to supine

position and preoxygenation is done with 100% oxygen for 3

minutes. All patients will receive glycopyrrolate (1µg/kg body

weight), fentanyl (2 µg/kg) as premedication. Following which

patient will be given induction with propofol and inhalational

agent. Each patient lay supine on a flat level operating table, the

inclinometer is placed on forehead and neck straightened till it is

horizontal to the floor . Standard mask ventilation procedure will

be followed with 2 hand technique. Intubation will be attempted

with laryngoscopes allotted in each group with as minimal neck

movement as possible. . Inclinometer angle will be measured at

five points 1. At neutral before induction, 2. Before mask

ventilation, 3. At point of successful mask ventilation, 4. Best

glottic view, 5. At the pot of et insertion. Also hans scale for mask

ventilation, CL grading, and Intubation Difficulty Scale (IDS)

scores were assessed and recorded for all patients.Therefore,

neutral position was applied to the head before the laryngoscopy.

In this procedure, the head was stabilized as the infraorbital edge

and tragus is perpendicular to the ground.An inclinometer (a 360

degree angle gauge) was placed on the forehead of the patients, so

that the tip of the inclinometer fit the glabellar line The inner

diameters of the intubation tubes used for females and males were

7 to 7.5 mm and 8 to 8.5 mm, respectively(2). The maximum angle of

cervical extension was measured by an inclinometer. The head was

neutrally positioned and the degree that the inclinometer showed

was recorded. Then, the maximum degree shown by the inclinometer

during laryngoscopy and tracheal intubation was recorded. The

maximum angle of cervical extension was measured by subtracting

the first and last recorded degree(2). An IDS score (3) of IDS 0

=(easy intubation) IDS 1 to 5 suggests (slight difficulty), and IDS

≥5 denotes a (difficult intubation).The duration from the

laryngoscope blade passing the lips and the placement of the tube

into trachea is recorded as the intubation process time (IPT).If the

IPT was more than 120 seconds, the patients will be ventilated for 1

minute with a face mask, and then intubation will be performed

using a fiberoptic laryngoscope for unsuccessful ones(2) . Those

patients will be excluded from the study. Finally, all of the

patients will be intubated.