Comparison of the laryngoscopy views with the size 1 Miller and Macintosh laryngoscope blades lifting the epiglottis or the base of the tongue in infants and children <2 yr of age

Background: Miller laryngoscope blades are preferred for laryngoscopy in infants and children <2 yr of age. Despite their long history, the laryngeal view with the Miller blade size 1 has never been compared with that with the Macintosh (MAC) blade in children. This prospective, single-blinded, randomized study was designed to compare the laryngeal views with the size 1 Miller and MAC blades in children <2 yr.

Methods: With IRB approval, 50 ASA I and II children <2 yr undergoing elective surgery were enrolled. After an inhalation induction and neuromuscular block with i.v. rocuronium 0.5 mg kg(-1), two laryngeal views were obtained with a single blade (Miller or MAC) in each child: one lifting the epiglottis and another lifting the tongue base. The best laryngeal views in each blade position were photographed with a SONY(®) Cyber-shot camera and rated by a blinded anaesthesiologist using the percentage of glottic opening scale.

Results: The scores with the Miller blade lifting the epiglottis and the MAC blade lifting the tongue base were similar. The scores with the Miller blade lifting the epiglottis and the tongue base were similar. The scores for the MAC blade lifting the tongue base were greater than those lifting the epiglottis (95% confidence interval: 7.6-26.8) (P=0.0004).

Conclusions: In infants and children <2 yr of age, optimal laryngeal views may be obtained with either the Miller size 1 blade lifting the epiglottis or with the Miller or MAC blades lifting the tongue base.

Clinical trial registration: NCT01717872 at Clinical Trials.gov.