Effects of cervical spine immobilization technique and laryngoscope blade selection on an unstable cervical spine in a cadaver model of intubation

Study objective: Orotracheal intubation (OTI) is commonly used to establish a definitive airway in major trauma victims, with several different cervic al spine immobilization techniques and laryngoscope blade types used. This experimental, randomized, crossover trial evaluated the effects of manual i n-line stabilization and cervical collar immobilization and 3 different lar yngoscope blades on cervical spine movement during OTI in a cadaver model o f cervical spine injury. Methods: A complete C5-C6 transection was performed by using an osteotome o n 14 fresh-frozen cadavers. OTI was performed in a randomized crossover fas hion by using both immobilization techniques and each of 3 laryngoscope bla des: the Miller straight blade, the Macintosh curved blade, and the Corazel li-London-McCoy hinged blade. Intubations were recorded in real time on flu oroscopy and then transferred to video and color still images. Outcome meas ures included movement across C5-C6 with regard to angulation expressed in degrees of rotation and axial distraction and anteroposterior displacement with values expressed as a proportion of C5 body width. Cormack-Lehane Visu alization grades were also recorded as a secondary outcome measure. Data we re analyzed by using multivariate analysis of Variance to test for differen ces between immobilization techniques and between laryngoscope blades and t o detect for interactions. Significance was assumed for P values of less th an .05. Results: Manual in-line stabilization resulted in significantly less moveme nt than cervical collar immobilization during OTI with regard to anteropost erior displacement. Use of the Miller straight blade resulted in significan tly less movement than each of the other 2 blades with regard to axial dist raction. The Cormack-Lehane grade was significantly better with manual inli ne stabilization versus cervical collar immobilization; no differences were observed between blades. Conclusion: Manual in-line stabilization results in less cervical subluxati on and allows better vocal cord visualization during OTI in a cadaver model of cervical spine injury. The Miller laryngoscope blade allowed less axial distraction than the Macintosh or Corzelli-London-McCoy blades. The clinic al significance of this degree,of movement is unclear.