Assessment of cervical spine movement during laryngoscopy with Macintosh and Truview laryngoscopes

BACKGROUND: Truview laryngoscope provides an indirect view of the glottis and will cause less cervical spine movement since a ventral lifting force will not be required to visualize the glottis compared to Macintosh laryngoscope. MATERIALS AND METHODS: A randomized crossover study to assess the degree of movement of cervical spine during endotracheal intubation with Truview laryngoscope was conducted in 25 adult ASA-I patients. After a standard anesthetic technique laryngoscopy was performed twice in each patient using in turn both the Macintosh and Truview laryngoscopes. A baseline radiograph with the head and neck in a neutral position was followed by a second radiograph taken during each laryngoscopy. An experienced radiologist analyzed and measured the cervical movement. RESULTS: Significant cervical spine movement occurred at all segments when compared to the baseline with both the Macintosh and Truview laryngoscopes (P < 0.001). However, the movement was significantly less with Truview compared to the Macintosh laryngoscope at C(0)–C(1) (21%; P = 0.005) and C(1)–C(2) levels (32%; P = 0.009). The atlantooccipital distance (AOD) traversed while using Truview laryngoscope was significantly less than with Macintosh blade (26%; P = 0.001). Truview blade produced a better laryngoscopic view (P = 0.005) than Macintosh blade, but had a longer time to laryngoscopy (P = 0.04). CONCLUSION: Truview laryngoscope produced a better laryngoscopic view of glottis as compared with Macintosh laryngoscopy. It also produced significantly less cervical spine movement at C(0)–C(1) and C(1)–C(2) levels than with Macintosh laryngoscope in patients without cervical spine injury and without manual in-line stabilization (MILS). Further studies are warranted with Truview laryngoscope using MILS.