What is the recommended endotracheal tube (ETT) size for pediatric patients?

Endotracheal Tube Size Selection in Pediatric Patients

For pediatric patients, the recommended endotracheal tube (ETT) size is 3.0 mm internal diameter (ID) for infants under 1 year, 3.5 mm ID for children 1-2 years, and for children over 2 years, the formula 3.5 + (age/4) mm should be used for cuffed tubes. 1

Age-Based Recommendations for ETT Size

Cuffed Endotracheal Tubes

• Infants <1 year: 3.0 mm ID 1
• Children 1-2 years: 3.5 mm ID 1
• Children >2 years: Use formula: 3.5 + (age/4) mm 1

Uncuffed Endotracheal Tubes

• Infants <1 year: 3.5 mm ID 1
• Children 1-2 years: 4.0 mm ID 1
• Children >2 years: Use formula: 4 + (age/4) mm 1

Practical Application

1. Calculate the appropriate ETT size using the age-based formulas above
2. Always have tubes 0.5 mm smaller and larger than the calculated size available 1
3. If resistance is met during insertion, use a tube 0.5 mm smaller 1
4. If there is a large air leak around an uncuffed tube that interferes with ventilation, consider replacing with a tube 0.5 mm larger or using a cuffed tube of the same size 1
5. For cuffed tubes, if there is no leak with the cuff deflated, consider reintubating with a tube 0.5 mm smaller when the patient is stable 1

Alternative Methods for ETT Size Selection

While age-based formulas are standard, they're not always accurate for all children. Alternative methods include:

• Length-based methods: Length-based resuscitation tapes are more accurate than age-based formulas for children up to 35 kg, even for those with short stature 1, 2
• Ultrasonography: Measuring the subglottic diameter with ultrasound can provide accurate ETT size estimation 3

Important Considerations

• Cuffed vs. Uncuffed: Both cuffed and uncuffed ETTs are acceptable for pediatric intubation 1
• Advantages of cuffed tubes:
  • Higher likelihood of correct tube size selection
  • Lower reintubation rates
  • Decreased risk of aspiration 1
• When using cuffed tubes: Monitor and limit cuff inflation pressure according to manufacturer's instructions (usually <20-25 cm H₂O) 1
• Special circumstances: In cases of poor lung compliance, high airway resistance, or large glottic air leak, cuffed ETTs may be preferable 1

Verification of Proper ETT Placement

After intubation, verify proper placement through:

• Clinical assessment (bilateral chest expansion, lung auscultation)
• Capnography (optimal method) or colorimetric CO₂ detector 4
• Securing the tube at the appropriate depth
• Documentation of tube depth 4

Common Pitfalls to Avoid

1. Relying solely on age-based formulas without having alternative sizes available
2. Using adult-sized equipment for pediatric patients
3. Failing to verify tube placement immediately after intubation
4. Improper cuff inflation leading to tracheal damage or inadequate ventilation
5. Not securing the tube adequately, risking displacement during patient movement

The evidence strongly supports using age-based formulas for initial ETT size selection, with appropriate adjustments based on clinical response. Length-based methods offer superior accuracy when age is unknown or in children with atypical body proportions 2.