Types of Blades for Direct Laryngoscopy
Direct laryngoscopy refers to a technique whereby the operator uses a blade, under direct visualization as opposed to through a camera lens (i.e., indirect laryngoscopy), to facilitate view of the epiglottis, glottic opening, and surrounding structures. This technique is most frequently utilized for endotracheal intubation.1 Medical device manufacturers have developed a range of blades for direct laryngoscopy, each with its own characteristics.
Direct laryngoscopy blades can broadly be categorized by their shape: curved or straight. The most commonly utilized curved blade is the Macintosh (Mac) blade.1 The Macintosh blade is used by advancing the tip into the vallecula, oppositional to the hypoepiglottic ligament, facilitating lifting of the epiglottis for better visualization of the glottic opening.1 The McCoy blade, developed in 1993, is an alteration of the Macintosh blade.2 The blade is similar to the Macintosh blade with the addition of a hinged tip which can be controlled by a lever to facilitate elevation of the epiglottis irrespective of lifting. The thought is that this blade may provide specialized benefit in patients with anterior airways.2 The Bizzarri-Giuffrida blade is also similar to the Macintosh blade; however, it does not contain a vertical flange. The idea behind the exclusion is that it will enable easier manipulation in the oral cavity of those with small oral apertures or for whom there is a concern for dental damage.3
The most frequently utilized straight blade is the Miller blade. The miller blade is advanced over the epiglottis, pinning it to allow for visualization of the glottic opening.1 The Wisconsin blade is similar to the Miller; however, its flange expands more distally along the blade, potentially increasing the visual field and reducing the likelihood of a traumatic intubation.4
The choice between blades for direct laryngoscopy is predominantly influenced by availability and provider preference. However, there are certain circumstances wherein data suggests the use of one blade type over others. A 2019 randomized controlled trial yielded data suggesting that the Miller blade (Intubation Difficulty Score [IDS] 0.6 ± 0.7, P = 0.002; Percentage of Glottic Opening [POGO] 86 ± 23.4, P < 0.001) is superior to Macintosh (IDS 1.4 ± 0.9; POGO 68.2 ± 20.5) and McCoy (IDS 1.3 ± 1.1; POGO 59.8 ± 28.9) blades in generating glottic visualization for greater ease of intubation in pediatric populations aged 2–6.5
There are numerous blades at the disposal of practitioners to facilitate direct laryngoscopy. These blades can be largely divided into straight and curved bodies. Of straight blades, the most common is the Miller blade. Of curved blades, the most common is the Macintosh blade. Blades other than the Macintosh and Miller blades offer alterations with the hope of improving visualization or mitigating the likelihood of an anticipated adverse outcome (e.g., dental damage, inability to successfully perform endotracheal intubation due to an anterior airway). Despite this, blade choice is largely influenced by availability and provider preference. However, for children aged 2–6 years, data suggests Miller blades may provide superior visualization over Macintosh and McCoy blades.
References
1. Peterson K, Ginglen JG, Desai NM, Guzman N. Direct Laryngoscopy. In: StatPearls. StatPearls Publishing; 2025. Accessed September 4, 2025. http://www.ncbi.nlm.nih.gov/books/NBK513224/
2. McCOY EP, Mirakhur RK. The levering laryngoscope. Anaesthesia. 1993;48(6):516-519. doi:10.1111/j.1365-2044.1993.tb07075.x
3. Bizzarri DV, Giuffrida JG. Improved laryngoscope blade designed for ease of manipulation and reduction of trauma. Anesth Analg. 1958;37(4):231-232.
4. SHURSHIP. Laryngoscope blades/standard. Mercury Med. Published online 2025. https://mercurymed.com/catalogs/ShurShip_LaryngoscopesBladesStandard.pdf
5. Yadav P, Kundu SB, Bhattacharjee DP. Comparison between Macintosh, Miller and McCoy laryngoscope blade size 2 in paediatric patients – A randomised controlled trial. Indian J Anaesth. 2019;63(1):15-20. doi:10.4103/ija.IJA_307_18