Interpretation
| Result | Meaning |
|---|---|
| Uncuffed | (age/4) + 4 mm ID |
| Cuffed | (age/4) + 3.5 mm ID |
| Depth | 3 × tube ID (cm) at the lip, or age/2 + 12 |
Formula
Uncuffed ID (mm) = age/4 + 4 (modified Cole) · Cuffed ID = age/4 + 3.5 (PALS) · Oral depth (cm) = 3 × ID or age/2 + 12
Clinical pearls
- Formulas apply from age 2; infants typically take a 3.0–3.5 mm cuffed tube (3.5 mm uncuffed). Have tubes 0.5 mm smaller and larger ready.
- Cuffed tubes are now preferred in most settings; keep cuff pressure < 20–25 cmH₂O.
- Confirm placement with capnography and chest radiograph; depth formulas are estimates.
Examples
FAQ
What size ETT for a 4-year-old?
Uncuffed 5.0 mm (4/4 + 4) or cuffed 4.5 mm (4/4 + 3.5), inserted about 15 cm at the lip.
How deep should a pediatric ETT go?
About 3 times the tube internal diameter in centimetres at the lip, or age/2 + 12 cm for oral tubes.
Evidence
- Khine HH et al. Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology 1997;86:627–31.
- Cole F. Pediatric formulas for the anesthesiologist. AMA J Dis Child 1957;94:672–3.
- Topjian AA et al. Part 4: Pediatric Basic and Advanced Life Support: 2020 AHA Guidelines for CPR and ECC. Circulation 2020;142:S469–523.