Medical Minute: Miller vs Macintosh blade to intubate infants

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September 23, 2014 by dailybolusoflr

By Amanda Crichlow, MD

The traditional recommendation is to use the Miller blade to intubate infants. But the question arises, have the blades ever been directly compared to one another in this population?

The following study seeks to address this question:

Passi Y et al. 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. Br J Anaesth 2014 doi:10.1093/bja/aeu228.

Prospective, single-blinded, randomized study

50 ASA 1 and 2 children < 2 yr  undergoing elective surgery

Each child was randomized to have the larynx visualized by either the 1 Miller or 1 Macintosh blade

All laryngoscopies in the study were conducted by the same pediatric anesthesiologist

2 views of the larynx were obtained in each child with the same laryngoscope blade (1- direct lifting of the epiglottis & 2- lifting the tongue base with blade placed in vallecula) & photographs taken by another anesthesiologist

A third anesthesiologist, who was blinded to which blade was utilized, reviewed the pictures and determined the POGO score (POGO score = Percentage of glottis opening score = portion of glottis visualized) and the POGO scores compared between the Miller directly lifting epiglottis & the Mactinosh with blade in vallecula

Picture obtained from: Ochroch et al. Assessment of laryngeal view: Percentage of glottis opening score vs Cormack and Lehane grading. Can J Anaesth 1999; 46: 987-90.

Study results: The POGO scores for the Miller and Macintosh blade were similar (mean scores of 78.4 (70-87) vs 84.4 (76.5-92.3) respectively)

Conclusion: The laryngeal views obtained with the Miller and Macintosh laryngoscope size 1 blades when used in children < 2 yrs of age were similar. This study has many limitations but the traditional teaching may be called into question. You be the judge, read the paper J



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