Laryngoscope

1. Basic Components

A. Handle

• Contains batteries 
• Provides power to light source
• Sizes:
• Adult (standard)
• Pediatric (short handle for difficult airway,Polio handle)

B. Blade

• Attaches to handle
• Contains light source (bulb/fiberoptic/LED)
• Used to displace tongue and soft tissues

C. Light Source

• Types:
• Conventional bulb
• Fiberoptic bundle
• LED (modern standard → brighter, durable)

2. Types of Laryngoscopes

A. Direct Laryngoscopes

(1) Macintosh Blade (Curved)

Mechanism:

• Tip placed in vallecula
• Lifts epiglottis indirectly

Features:

• Most commonly used in adults
• Less trauma to epiglottis
• Requires alignment of:
• Oral
• Pharyngeal
• Laryngeal axes

Sizes:

• 3 → Adult female
• 4 → Adult male

(2) Miller Blade (Straight)

Mechanism:

• Directly lifts epiglottis

Features:

• Preferred in:
• Infants & pediatrics
• Floppy epiglottis
• Better glottic exposure in some difficult airways

B. Video Laryngoscopes (VL)

Examples:

• GlideScope
• C-MAC
• McGrath MAC

Mechanism:

• Camera at blade tip → indirect visualization

Advantages:

• No need for axis alignment
• Better Cormack-Lehane grade
• Higher success in difficult airway
• Teaching tool (shared screen)

Disadvantages:

• Expensive
• Fogging, secretions affect view
• Requires learning curve

C. Specialized Laryngoscopes

(1) McCoy Blade

• Hinged tip → lifts epiglottis
• Useful in difficult airway

(2) Optical Laryngoscopes

• e.g., Airtraq
• Uses optical channel for indirect view

(3) Rigid Fiberoptic Laryngoscope

• Hybrid between direct and fiberoptic

3. Blade Sizes 

4. Laryngoscopy Technique 

Positioning

• Sniffing position(Neck flexion + head extension)
• Neck flexion(Head elevation with pillow (≈ 7–10 cm)) → aligns pharyngeal + laryngeal axes
• Head extension → aligns oral + pharyngeal axes

• In obese → ramped position

Steps

1. Open mouth (scissor technique)
2. Insert blade from right side
3. Sweep tongue to left
4. Advance blade:
• Macintosh → vallecula
• Miller → lift epiglottis

5. Lift upward and forward (NOT levering on teeth)

5. Cormack-Lehane Grading

VL improves grade significantly 

6. Complications

Mechanical

• Dental trauma (most common)
• Soft tissue injury
• Esophageal intubation

Physiological

• Tachycardia, hypertension (sympathetic response)
• Raised ICP
• Hypoxia
• Arrhythmias

7. Direct vs Video Laryngoscopy 

8. Recent Guidelines & Evidence 

• Video laryngoscopy preferred in ICU intubations
• Reduces:
• Failed first attempt
• Esophageal intubation
• Improves safety in:
• Hypoxemic patients
• Difficult airway

Supported by:

• ICU airway guidelines (e.g., Difficult Airway Society, SCCM-based practices)
• Increasing shift toward VL-first approach