The aim of the study is to compare the effect of the laryngoscope-assisted lightwand intubation technique vs. the conventional lightwand intubation technique on the cervical spine motion during intubation in patients with the simulated cervical immobilization.

In clinical practice, the investigators have occasionally experienced some difficulties in the lightwand intubation in patients with cervical spine instability because manual in-line stabilization during intubation hinders free movements of the lightwand such as advancement, withdrawal, and scooping in the oral cavity. For this reason, jaw thrust is often used to secure enough space for free movements of the lightwand in the oral cavity in the traditional lightwand intubation technique. A recent study showed that laryngoscope-assisted lightwand intubation provided more successful intubation on the first attempt and less scooping movement than the traditional lightwand intubation by facilitating free movements of the lightwand in the oral cavity in patients with cervical immobilization during intubation for cervical spine surgery. In the laryngoscope-assisted lightwand intubation technique, the direct laryngoscope may provide sufficient space for free movements of the lightwand in the oral cavity without jaw thrust, which can result in cervical spine movement. However, the effect of the laryngoscope-assisted lightwand intubation technique on cervical spine motion is not investigated yet.

Inclusion Criteria:

• Patients with American Society of Anesthesiologists physical status of 1-2 and age of 18-80 years undergoing elective endovascular coiling to secure cerebral aneurysm under general anesthesia in neuroangiographic rooms.

Exclusion Criteria:

• Patients with the upper airway abnormalities, such as inflammation, abscesses, tumours, polyps, or trauma.
• Patients with past medical history of gastro-oesophageal reflux disease and previous airway surgery, a high risk of aspiration, coagulation disorders, or Hunt Hess grade of 3-5.
• Body mass index > 30