Published in Br J Anaesth 2014 Jul 25
Authors: Passi Y et al.
Similar laryngeal views were achieved with both devices.
The straight Miller laryngoscope blade is traditionally recommended for intubation in infants, due to the large size and flexibility of the infant epiglottis. However, the Miller and Macintosh blades have not been systematically compared in young children. In a prospective, single-blind, randomized study, researchers compared laryngeal views obtained with size 1 Miller and Macintosh blades in 50 patients younger than 2 years (age range, 4 to 23 months) undergoing elective surgery.
Two photographs of the laryngeal view were taken with each blade: one while lifting the epiglottis and one while lifting the tongue base. An anesthetist blinded to the study reviewed the photos and assigned a percentage of glottic opening (POGO) score, with a full view of the laryngeal inlet constituting a score of 100. Mean POGO scores for the Miller blade when lifting the epiglottis and the Macintosh blade when lifting the tongue base (the primary comparison) were similar (78.4 and 84.4). With the Miller blade, mean POGO scores were similar when lifting the epiglottis and the tongue base, whereas with the Macintosh blade, mean scores were significantly higher when lifting the tongue base than the epiglottis (84.4 vs. 67.2).
The finding that the two direct laryngoscope blades — Miller and Macintosh — performed similarly calls into question the tradition of using a straight Miller blade for intubating infants. Video laryngoscopy should be used when available, and this study suggests that a curved blade should work as well as a straight blade.