What is the preferred laryngoscope blade, Miller or Mac, for first pass success in tracheal intubation?

Miller vs Macintosh Blade for First Pass Success in Tracheal Intubation

For tracheal intubation, neither the Miller straight blade nor the Macintosh curved blade is definitively superior for first pass success, and clinicians should use the blade they are most familiar with, switching to the alternative blade if the first attempt fails. 1

Blade Characteristics and Performance

Straight vs Curved Blades

• Miller (straight) blade:

  • Better laryngoscopic view/visualization of the glottis 2
  • Requires lifting the epiglottis out of the line of sight
  • Particularly useful in pediatric patients under 2 years of age 1

• Macintosh (curved) blade:

  • Better intubating conditions and ease of intubation 2
  • Inserted into the vallecula, depressing the hyoepiglottic ligament
  • Flips the epiglottis upwards to expose the laryngeal inlet 1

Evidence on Blade Performance

Research shows that straight blades like Miller provide better laryngoscopic views, while curved blades like Macintosh offer better intubating conditions 2. This creates a trade-off between visualization and ease of tube placement.

Clinical Recommendations

Adult Patients

• The Macintosh laryngoscope remains the most popular device for first intubation attempt in adults 1
• Metal blades should be used for direct laryngoscopy to improve success rates (Grade 1+ recommendation) 1
• Plastic disposable blades are not recommended for situations where difficult intubation is anticipated 1

Pediatric Patients

• For children in PICU settings, either Miller straight blade or Macintosh curved blade can be used based on clinician familiarity 1
• After failure to achieve adequate laryngeal view with one blade, an attempt with the alternative blade should be made (Grade 2+ recommendation) 1
• Studies in children under 2 years found no significant difference in laryngoscopic views between Miller and Macintosh blades 1

Special Considerations

Difficult Airways

• For anticipated difficult airways, consider videolaryngoscopy either initially or after failed direct laryngoscopy 1, 3
• The ASA guidelines recommend videolaryngoscopy as a selective tool in airway management 3
• In specific scenarios like retromolar laryngoscopy, Miller blade may provide significantly better vocal cord visualization 4

Technique Optimization

• For Miller blades, proper technique involves lifting the epiglottis directly
• For Macintosh blades, proper placement in the vallecula is essential
• Consider using a stylet with endotracheal tubes to reduce intubation time, particularly with video laryngoscopy 5

Algorithm for Blade Selection

1. First attempt: Use the blade the clinician is most experienced with
2. If first attempt fails: Switch to alternative blade design
3. If both attempts fail: Consider videolaryngoscopy or other advanced airway techniques 1, 3

Pitfalls to Avoid

• Relying solely on blade type without considering operator experience
• Failing to switch blades after an unsuccessful first attempt
• Not considering videolaryngoscopy for patients with predicted difficult airways
• Using plastic blades in anticipated difficult intubation scenarios

The choice between Miller and Macintosh blades should be guided by clinician experience and specific patient characteristics, with readiness to switch techniques if the first attempt is unsuccessful.