Paediatric estimation - Airway equipments





Laryngoscope

Less than 4 kg → Straight Magill blades size 0

6 to 10kg → Curved blade

NB:

  • Choice varies greatly according to personal preferences
  • Remember the best tool is usually one that you know best.

Endotracheal tubes

Generally use uncuffed ETT until 6 to 8 years old

  • Except if microcuff ETTs available
  • Small leak should be present

ETT size

Cole's formula for size (internal diameter) for uncuffed ETTs = Age / 4 + 4

NB:

  • From 2 to 10 years old
  • Consider +0.5 size to get better fit
  • One size smaller (-0.5 mm) if microcuff
  • Use same size for nasal and oral

Sizes depending on weight of neonate

  • Less than 1000 g
    → Size 2.5

  • 1000 to 2000 g
    → Size 2.5 to 3

  • 2000 to 3000 g
    → Size 3 to 3.5

  • Greater than 3000 g
    → Size 3.5 to 4
    (i.e. Normal neonates)

NB:

  • APLS and resus uses 3 to 3.5 mm for newborn
    • ?? Maybe the difference is because they are newborn, not neonates
  • Average term baby = 3.5 kg
    ∴ Average ETT size for term baby = 3.5 mm

ETT length at lip

Per APLS

Formula for length at lip
= Age / 2 + 12 cm

NB:

  • Add 2 to 3 cm if nasal intubation

Length at lips for neonates

Formula for length at lip (for neonates)
= Weight + 6 cm

Average for term = 9.5 cm

Alternative

Per Pediatric Anesthesia 2006(16)p1238-1243

Length at lip for children > 1 yo
= Age / 2 + 13 cm

NB:

  • Add 2 cm if nasal

Length at lip for children < 1 yo
= Weight / 2 + 8

NB:

  • Add 1 cm if nasal

Cuffed ETTs

  • Review article in Paediatric Anaesthesia 2014 by Tobias found that uncuffed ETT can exert too much pressure on lateral walls due to the elliptical shape, even when a leak is present

  • Microcuff ETTs are:

    • Ultra-thin cuff (10 µm) made of polyurethane
    • Cuff more distal
    • The base of the cuff is shorter in length (making the cuff more spherical)
    • No Murphy eye
    • Smallest one is 3.0 mm
      • Suitable for full term infants weighing more than 3 kg
      • i.e. Not for pre-term or infants weighing less than 3 kg

LMA sizes

Size 1

  • Up to 5 kg
  • Max cuff = 4 mL

Size 1.5

  • 5 to 10 kg
  • Max cuff = 7 mL

Size 2

  • 10 to 20 kg
  • Max cuff = 10 mL

Size 2.5

  • 20 to 30 kg
  • Max cuff = 14 mL

Size 3

  • 30 to 50 kg
  • Max cuff = 20 mL