Evaluation of the Bullard, GlideScope, Viewmax, and Macintosh laryngoscopes using a cadaver model to simulate the difficult airway

Abstract

Study Objective To assess the performance and cervical (C)-spine movement associated with laryngoscopy using the Bullard laryngoscope (BL), GlideScope videolaryngoscope (GVL), Viewmax, and Macintosh laryngoscopes during conditions of a) unrestricted and b) restricted C-spine and temporomandibular joint (TMJ) mobility. Design Prospective, controlled, randomized, crossover study. Setting University teaching hospital. Subjects 21 cadavers with intact C-spine anatomy. Interventions Each cadaver underwent to total of 8 intubation attempts to complete the intubation protocol using all four devices under unrestricted and restricted C-spine and TMJ mobility. Measurements Laryngoscopic view was graded using the modified Cormack-Lehane system. Time to best laryngoscopic view and total time to intubation were recorded. C-spine movement was measured between McGregor's line and each vertebra from radiographs taken at baseline and at best laryngoscopic view. Main Results During both intubating conditions, the BL achieved the highest number of modified Cormack-Lehane grade 1 and 2A laryngoscopic views as compared to the other three devices ( P < 0.05) and had fewer intubation failures than the Viewmax or Macintosh laryngoscopes ( P < 0.05). The GVL had superior laryngoscopic performance as compared to the Viewmax and Macintosh laryngoscopes ( P < 0.05) and had fewer intubation failures than those two devices ( P < 0.05). All devices except the Macintosh laryngoscope in restricted mobility achieved median times to intubation in less than 30 seconds. For both conditions, BL showed the least total absolute movement between Occiput/C1 and C3/C4 of all the devices (all P < 0.05). Most of the difference was seen at C1/C2. Conclusions In cadavers with unrestricted and restricted C-spine mobility, the BL provided superior laryngoscopic views, comparable intubating times, and less C-spine movement than the GVL, Viewmax, or Macintosh laryngoscopes.