Cervical spine movements during laryngoscopy. Comparison of the Macintosh and McCoy laryngoscope blades.

We studied cervical spine movement in 10 patients scheduled for elective surgery under general anaesthesia. Each patient was fitted with a rigid cervical collar before undergoing direct laryngoscopy for orotracheal intubation. Laryngoscopy was performed using the McCoy laryngoscope in the activated position and the standard Macintosh blade. Displacement of the cervical spine at laryngeal exposure was measured using lateral cervical spine X-rays. Flexion and extension movements of the cervical spine during the use of the two laryngoscope blades were compared. For each blade, the greatest degree of extension occurred at the joint between the first and second cervical vertebrae. There was no significant difference in cervical spine movement when the two blades were compared.