Ease of intubation and incidence of dental injury during direct laryngoscopy: A randomized controlled trial comparing five different laryngoscope blades (Macintosh, Miller, Reduce flange, Blechman and Flangeless)

Abstract

BackgroundDirect laryngoscopy remains an invaluable and readily available option despite the increasing use of video laryngoscope for securing the airway in different situations, particularly in limited resource and unanticipated difficult airway scenarios. Several variations of the laryngoscope blades are available for various purposes. However, knowledge of the functioning of different blades in a similar controlled environment is required because of the unavailability of all blades in a given setting. AimThis study assessed the ease of intubation and the degree of dental injury with five types of laryngoscope blades (Macintosh, Miller, Reduced flange, Blechman, and Flangeless blade). MethodsThis prospective randomized controlled study was conducted in patients undergoing tracheal intubation with direct laryngoscopy using five different blades posted for elective surgery under general anesthesia in a single center.The primary outcome parameters were Cormack–Lehane grade and intubation difficulty score, whereas secondary outcome measures were the proportion and grades of dental injury. ResultsA Cormack–Lehane grade 3 view was observed more often with flangeless blades 7 (22.5%) than others, with the lowest incidence for the Macintosh blade 1 (3%) (p = 0.228). The first pass success rate was highest in Macintosh (94%), similar in reduced flange Macintosh and Blechman blades (90% each) and least in the flangeless blade (77%). The force required for laryngoscopy varied significantly between the blades (p < 0.001). The median interquartile range intubation difficulty score was the highest with flangeless blades [2 (2–3)] among all the groups (p = 0.048). The dental contact during laryngoscopy varied significantly between the groups (p < 0.001). The incidence of dental injury was the highest in flangeless (13%) among all the blades (p = 0.526). ConclusionsReduced flange Macintosh and Blechman blade had ease of intubation similar to standard Macintosh blade, where as flangeless blade is associated with more difficult intubations. Reduced flange Macintosh, and Blechman blades were associated with a lower incidence of dental contact and injury than other three study blades.