Cervical spine movement during orotracheal intubation: comparison of the Belscope and Macintosh blades

This study was designed to compare the degree of cervical spine movement during laryngoscopy and tracheal intubation using the Belscope and Macintosh laryngoscope blades. Twenty ASA 1 and 2 patients scheduled for elective surgery requiring tracheal intubation were studied. Following induction of anaesthesia and muscle relaxation, a neutral cross-table lateral cervical spine X ray was taken. Laryngoscopy was then performed in each patient using both the Belscope and Macintosh blades. After visualisation of the vocal cords and tracheal intubation the cervical spine X ray was repeated. Movement of the cervical spine was evaluated by tracing bony landmarks on each film and then superimposing the neutral and intubating films. We were unable to demonstrate a difference in the amount of cervical spine movement comparing the two blades. Using the Belscope blade, intubation took longer (median 18 s) than the Macintosh blade (median 12 s, p < 0.01) and was unsuccessful in two patients despite adequate visualisation of the vocal cords.