This study will be performed to compare ease and success rate of intubation with the straight and curved reinforced tubes using King vision video laryngoscope for tracheal intubation in patients to be operated for cervical spine instability admitted at SSG Hospital. We will do time-bound study, taking 5 cases per month, minimum 60 cases (30 cases in each group). After fulfilling all inclusion criteria, patient will be allotted to group, either Group S (straight reinforced endotracheal tube) or Group C (curved reinforced endotracheal tube) using envelope method. Thorough pre-anesthetic evaluation and informed written consent, premedication will be given. After 3 minutes of pre-oxygenation, patient will be induced. Post – induction, the King vision videolaryngoscope with loaded ET (either straight or curved) will be advanced from the centre of the tongue towards glottis by viewing on the screen of the monitor, and simultaneously with the view of glottis on monitor. Intubation will be attempted only if an optimal glottis view, with POGO score of ≥75% will be obtained. Maximum 2 attempts with the selected reinforced endotracheal tubes will be allowed. If it is not possible to direct the ETT toward the glottis, optimization manoeuvres like external laryngeal pressure, manipulation of King vision blade or use of bougie will be attempted to direct the ETT into the glottis after obtaining an optimal glottis view and will be assessed on a score of 0 to 2. Failed intubation will be defined as an attempt in which patient could not be intubated even with optimization manoeuvres or > 120 secs required to perform the procedures. Ease of intubation will be assessed and scored as good, satisfactory or poor. In case of failure, the patient will be intubated with standard PVC endotracheal tubes by using Macintosh laryngoscope after maintaining the manual in line stabilization and will be excluded from the study. Following parameters will be monitored and compared.

1. Time for intubation: Time in seconds taken from obtaining an optimal glottis view (75%) to first wave of Capnogram.

2. Percentage of glottic opening (POGO) score: A POGO score of 100% denotes visualization of the entire glottis from the anterior commissure of the vocal cords to the inter-arytenoid notch. If none of the glottic opening were visualized (even the inter-arytenoid notch is not seen), then the POGO score would be 0%.

3. No. of attempts of tube insertion: maximum two.

4. Incidence of impingement of tube with the arytenoids.

5. Optimization manoeuvres required for intubation like external laryngeal pressure or manipulation of King-vision blade or use of bougie.

6. Ease of intubation: Scored as good, satisfactory and poor.

7. Vital parameters: Hemodynamic parameters like heart rate, mean arterial pressure, SpO2 and ETCO2 to be noted at the time of induction, at time of intubation, after 2 minutes and 5 minutes.

8.   Complications like Fail to intubate (unable to perform endotracheal intubation using King Vision Video Laryngoscope in 2 attempts), Minor tongue/ lip/ dental trauma, Oesophageal intubation will be also monitored.

Data will be collected from multipara monitor and monitoring screen of King vision video laryngoscope and will be analyzed using Medcalc software. Descriptive statistics values will be expressed as mean ± SD (standard deviation) and p-value <0.05 will be considered as significant. Unpaired Student‘t’ test will be used for quantitative data and Chi square test will be used for the qualitative data like no of attempts, no of optimization manoeuvres and ease of intubation using Medcalc software.

The intubation is expected to be easy and with higher success rate using curved reinforced tube than straight reinforced tube.