Bedside Snapshot
- Use It When
- Any child needing airway support: bag-mask ventilation, intubation, SGA, or stridor assessment. Anatomy explains why small errors cost more. Use the sizing page for premature infants and Broselow when weight is unknown.
- Key Numbers
- Ventilation rate (advanced airway or breaths with a pulse): 20–30/min, 1 breath every 2–3 s
- Cuff pressure: usually under 20–25 cmH₂O
- Oxygen reserve: small; desaturates fast
- Trachea: about 4 cm in term neonates
- Formulas
- Cuffed ID (mm): age/4 + 3.5 (2 years and older)
Depth at lip (cm): ID × 3 (1 year and older; neonates by NRP weight chart)
Suction (Fr): ID × 2 - Action Thresholds
- Inspiratory stridor: upper airway; call the airway team
- Expiratory wheeze: lower airway
- Biphasic stridor: fixed lesion; escalate early
- Watch Out
- Deep tube means right mainstem; overinflated cuff injures the subglottis; gastric distension worsens ventilation. Confirm with capnography after every move.
Overview & Pediatric Differences
A child's airway is not a small adult airway. The head is big for the body. The tongue fills more of the mouth. The larynx sits higher and further forward. The subglottic space is narrow and cannot expand. The differences are greatest in infants and young children. They narrow toward adult anatomy through the early teens.
Kids burn through oxygen faster and keep less in reserve. They desaturate sooner during apnea or failed ventilation.
Why Kids Are Different
- Obstruction: The tongue is large, and young infants are obligate nasal breathers. Obstruction is the most common early problem.
- Larynx: High and anterior (about C3–C4 in infants versus C4–C6 in adults), with a floppy, omega-shaped epiglottis.
- Subglottis: The cricoid ring is the fixed part. It does not expand, so it still limits tube size. Imaging in sedated, unparalyzed children showed the narrowest point at the vocal cords.
- Trachea: Short, about 4 cm in term neonates. A small tube movement changes depth dramatically.
- Oxygen: They use more oxygen and hold a smaller functional residual capacity. That leaves less time before they desaturate.
The unifying concept: Airway resistance climbs steeply as the radius shrinks. In a simple tube model, add 1 mm of swelling all around the lumen. The diameter falls by 2 mm. In a 4 mm neonatal airway, that removes about 75% of the cross-sectional area. In an 8 mm adult airway, it removes only about 44%. Real airflow is less predictable than this model, but the direction is the same. Small swelling matters far more in a child.
Equipment & Sizing
Formulas give a starting point, not a final answer. Use them to pick the first tube and its depth. For the full size table, including premature infants, see ETT and Equipment Sizing.
Cuffed ETT (2 years and older)
ID (mm) = age/4 + 3.5
Uncuffed ETT (2 years and older)
ID (mm) = age/4 + 4
Oral depth at the lip (1 year and older)
cm = ID × 3
Suction catheter
French size = ID × 2
| Age | Cuffed ID (mm) | Uncuffed ID (mm) | Depth at Lip (cm) |
|---|---|---|---|
| Term neonate | 3.0–3.5 | 3.5 | NRP weight chart |
| 1 year | 3.5 | 4.0 | 10.5–12 |
| 2 years | 4.0 | 4.5 | 12–13.5 |
| 4 years | 4.5 | 5.0 | 13.5–15 |
| 6 years | 5.0 | 5.5 | 15–16.5 |
| 8 years | 5.5 | 6.0 | 16.5–18 |
| 10 years | 6.0 | 6.5 | 18–19.5 |
| 12 years | 6.5 | 7.0 | 19.5–21 |
| 14 years and older | 7.0 | 7.5–8.0 | 21 or more |
This page does not set blade or supraglottic airway sizes. Those live on the sizing page. Premature infants and neonates go by weight and gestation, per NRP and that page.
How to Use
- Estimate size: Use measured weight when available, then length-based tape (see Broselow Tape), then the age formula below.
- Calculate the cuffed tube: Internal diameter (ID) = age/4 + 3.5 mm for children 2 years and older. Prepare one half-size (0.5 mm) larger and one half-size smaller.
- Calculate depth: Oral depth at the lip = ID × 3 cm. Confirm with waveform capnography and bilateral breath sounds.
- Set suction: Catheter size (French) = ID × 2.
Worked example: Picture a 4-year-old with no scale reading and no tape. Estimate the weight first: (age + 4) × 2 gives 16 kg. Next, the cuffed ID: 4 ÷ 4 + 3.5 = 4.5 mm. Depth at the lip: 4.5 × 3 = 13.5 cm. Suction: 4.5 × 2 = 9 Fr. Then keep 4.0 mm and 5.0 mm cuffed tubes ready too.
Anatomy: Head & Neck
Positioning starts before the laryngoscope. The head and neck decide whether the airway is open before any device goes in.
| Feature | Infant / Child | Clinical Impact |
|---|---|---|
| Occiput | Proportionally large in infants | Supine position flexes the neck. A small shoulder roll brings the airway to neutral |
| Tongue | Large relative to the oral cavity | The most common cause of obstruction in an unconscious child. Jaw thrust or chin lift often clears it |
| Neck and trachea | Short neck; trachea about 4 cm in term neonates | Little room for landmarks. A small tube movement can cause right mainstem intubation or extubation |
| Cartilage | Soft and compliant | Excess flexion or extension can compress the trachea. Keep the head in neutral alignment |
| Head position | Neutral (sniffing) in infants; slight extension in older children | Correct positioning often restores airflow before an adjunct is needed |
Position first: In many pediatric airway emergencies, the right position opens the airway before a device is needed. Recheck after every move.
Anatomy: Larynx & Subglottis
The larynx changes with age in its position, its shape and how rigid it is. Each change affects how well you see the cords and how the tube passes.
| Feature | Infant / Young Child | Adult | Clinical Impact |
|---|---|---|---|
| Larynx position | High and anterior (about C3–C4) | C4–C6 | The cords are harder to see; the blade must reach further anteriorly |
| Epiglottis | Floppy, omega (Ω) shaped | Flatter and stiffer | A straight (Miller) blade can lift the epiglottis directly; a curved blade may not lift it well in infants |
| Vocal cords | Angled, with the front lower than the back | Perpendicular to the trachea | The tube tip can catch anteriorly; gentle rotation during insertion helps |
| Narrowest point | At the vocal cords in sedated, unparalyzed children (MRI); cricoid ring fixed below | At the glottis | Subglottic swelling still limits tube size, and a tube that passes the cords can wedge below them |
| Cartilage | Soft and compressible | Firm and calcified | Routine cricoid pressure has no proven benefit and can distort the airway; see Management Adjustments |
Why the funnel model changed: For years, textbooks drew the airway as a cone with the cricoid at its narrowest. Then a 2003 MRI study of sedated, unparalyzed children put the narrowest transverse dimension at the vocal cords. Method matters, so the narrowest level is not settled across every technique. Here's the practical point: the cricoid ring does not expand. A tube that clears the cords can still be too large below them.
Respiratory Physiology & Apnea Tolerance
Below the larynx, a child has less respiratory reserve for the demand placed on it. Problems show up fast during apnea and when the work of breathing rises.
| Feature | Infant / Child | Adult | Clinical Impact |
|---|---|---|---|
| Oxygen consumption | Higher per kg | Lower per kg | Faster desaturation during apnea or failed ventilation |
| Functional residual capacity | Small relative to need | Larger relative to need | Less oxygen reserve; preoxygenate fully and limit each attempt |
| Ribs | More horizontal | Angled downward | Less "bucket-handle" expansion; infants depend on the diaphragm |
| Chest wall | Compliant | Stiffer | Visible retractions with distress, but less mechanical support; paradoxical movement can occur |
| Stomach | Easily distended by air | Less prone | A full stomach limits diaphragm movement during bag-mask ventilation |
| Trachea | Short (about 4 cm in term neonates) | Longer | Tube position is more sensitive to small movements |
Children tolerate apnea for only a short time. Preoxygenate fully. Have equipment ready before the first attempt. When saturation falls, go back to bag-mask ventilation.
Common Pathology by Anatomy
Anatomy changes with age, so airway disease shows up in age-specific patterns.
| Condition | Anatomic Basis | Age Group | Key Feature |
|---|---|---|---|
| Croup (laryngotracheobronchitis) | Subglottic swelling in a naturally narrow segment | 6 months to 3 years | Barking cough and inspiratory stridor. A steeple sign on neck X-ray is supportive when imaging is done |
| Epiglottitis | Infection of the floppy epiglottis | Usually 2–7 years; rare since Hib vaccination | Drooling, tripod position, muffled voice, and little or no barking cough |
| Foreign body aspiration | Small airway; young children mouth objects | 1–3 years (peak) | Sudden choking or cough, with unilateral wheeze or asymmetric air entry |
| Bronchiolitis (RSV) | Small bronchioles with proportionally greater mucus obstruction | Under 2 years | Wheeze, crackles, tachypnea, nasal flaring, and poor feeding |
| Peritonsillar abscess | Large tonsillar tissue in the oropharynx | Adolescents | Muffled "hot potato" voice, trismus, uvular deviation, and unilateral swelling |
Airway Management Adjustments
Each anatomic difference changes a management step. The table gives the pediatric adjustment for each task.
| Task | Pediatric Adjustment | Why It Matters |
|---|---|---|
| Positioning | Neutral (sniffing) for infants with a shoulder roll if needed; slight extension for older children | Often restores airflow without an adjunct |
| Bag-mask seal | Mask on the bridge of the nose and the mentolabial fold, not over the chin; avoid pressure on the eyes | Eye pressure can trigger vagal bradycardia; two-person technique with two-handed jaw thrust is preferred |
| Ventilation rate with an advanced airway | 20–30/min (1 breath every 2–3 s), adjusted for age (2025 AHA Part 8, COR 2b, LOE C-LD) | Avoids hypoventilation and hyperventilation; hyperventilation may compromise hemodynamics. An observational study linked at least 30/min under 1 year and at least 25/min older with better ROSC |
| Breaths with a pulse, no advanced airway | 1 breath every 2–3 s (20–30/min) when respiratory effort is absent or inadequate (2025 AHA Part 6, COR 2a, LOE C-EO) | Restores oxygenation and ventilation before arrest occurs |
| Tidal volume | Lowest volume that produces visible chest rise | Excess volume fills the stomach and splints the diaphragm |
| Cardiac arrest, out of hospital | Bag-mask ventilation rather than tracheal intubation or SGA placement is reasonable (2025 AHA Part 8, COR 2a, LOE C-LD) | Advanced airway placement can interrupt compressions or be malpositioned. In hospital, bag-mask ventilation or an advanced airway may be reasonable (COR 2b, LOE C-LD) |
| Laryngoscope blade | Straight blade lifts the floppy epiglottis; curved blade used in older children; blade choice per local protocol | Video laryngoscopy is used where available; the view is still limited by anatomy |
| External laryngeal manipulation | An assistant holds the larynx in the best position found by the operator | Can improve the view when cords are hard to see |
| Cricoid pressure | No routine use during bag-mask ventilation or intubation (2025 AHA Part 8, COR 3: No Benefit, LOE C-LD); stop if it interferes with ventilation or intubation (COR 3: Harm, LOE C-LD) | A registry study found no lower regurgitation rate; a bronchoscopic study of 30 children showed airway distortion at forces below usual guidance |
| Tube choice | Cuffed tube reasonable to choose over uncuffed (2025 AHA Part 8, COR 2a, LOE B-NR); check size, position and cuff pressure, usually under 20–25 cmH₂O (COR 1, LOE C-EO) | A 2009 multicentre trial of 2,246 children found cuffed tubes reduced tube exchanges (2.1% vs 30.8%) without more post-extubation stridor (4.4% vs 4.7%). A 1997 trial found a cuffed-tube selection formula appropriate for young children |
For neonates, tube type, sizing, depth and supraglottic airways follow NRP and local protocol. See References.
Interpretation & Action Thresholds
Before you examine the child, the phase and pattern of breathing sounds narrow the cause. The table pairs each finding with the action it calls for.
| Finding | Meaning | Action |
|---|---|---|
| Inspiratory stridor at rest | Upper airway (extrathoracic) obstruction: croup, epiglottitis, or a laryngeal foreign body | Keep the child calm; avoid throat examination unless ready to intubate; call the airway team |
| Expiratory wheeze | Lower (intrathoracic) airway: bronchiolitis, asthma or a bronchial foreign body | Treat the lower airway; watch for asymmetry, which points to a bronchial foreign body |
| Biphasic stridor | Fixed or severe obstruction at the glottis, subglottis or trachea | Escalate early; expert airway help |
| Child becomes quiet during distress | Possible fatigue, not improvement | Reassess immediately; prepare to support ventilation |
| Poor chest rise with bag-mask | Airway not open, seal leak, or a full stomach | Re-position, use two-person technique and OPA or NPA, and decompress the stomach |
| Failed ventilation and failed intubation | Cannot oxygenate | Optimize bag-mask ventilation (two-person technique, adjuncts), then place a properly sized supraglottic airway. If oxygenation still fails, use a front-of-neck airway per protocol: needle cricothyrotomy in infants and young children; surgical cricothyrotomy is generally avoided under about 12 years. See Cricothyrotomy for age-specific guidance |
Pitfalls & Safety Checks
| Pitfall | Consequence | Prevention |
|---|---|---|
| Uncuffed tube too large or leaking | Air leak, poor ventilation, tube exchange | Size from the formula, have ±0.5 mm ready, check the leak |
| Cuff overinflation | Mucosal injury; subglottic stenosis | Monitor cuff pressure with a manometer; keep usually under 20–25 cmH₂O |
| Tube too deep | Right mainstem intubation; one lung ventilated | Depth = ID × 3 at the lip; confirm with capnography and bilateral breath sounds |
| Tube moved during transport or a log roll | Extubation or endobronchial placement | Secure the tube; reassess after every move |
| Stomach distended by bag-mask air | Diaphragm splinting, lower ventilation, aspiration risk | Use only the volume needed for chest rise; insert an OG or NG tube early during prolonged bag-mask ventilation |
| Routine cricoid pressure | Impaired view or ventilation | Not routine (2025 AHA Part 8, COR 3: No Benefit); stop if it interferes with ventilation or intubation (COR 3: Harm) |
| Long intubation attempts | Desaturation; loss of oxygenation | Preoxygenate, limit each attempt by local protocol, and return to bag-mask ventilation between attempts |
| Adult-sized equipment for a child | Wrong tube or blade | Use length or age tools to size; see the sizing page |
Oxygenation comes first: If saturation falls during an attempt, stop, ventilate and reset. The emergency is the failure to oxygenate, not the failed attempt.
Special Populations
Neonates and Young Infants
- Protocol: Neonatal delivery-room airway, tube size and depth follow NRP and local protocol. The tube formulas here start at 2 years, and the depth formula at 1 year.
- Nasal breathing: Young infants breathe mainly through the nose. Congestion can cause respiratory distress.
Adolescents
- Switch point: Protocols differ. Some switch at puberty, some at a weight such as 40 kg, and some when the child passes the length-based tape. Follow local protocol. The length-based tape is accurate only up to about 35 kg (2025 Korean PALS review).
Children with Special Health Care Needs
- Tracheostomy: Use the stoma as the airway route when oral intubation is not needed; bring the child's usual trach size and suction.
- Emergency Information Form: Check for a current form that lists tube size, device history and baseline function.
Prehospital & Transport Considerations
Each level and agency draws the line differently. The roles below are the usual ones. Local protocol says what each level may do.
| Level | Typical Role in This Topic |
|---|---|
| EMT | Positioning, suction, pediatric bag-mask ventilation with adjuncts, and oxygen |
| AEMT | Adds supraglottic airway use where protocol allows |
| Paramedic | Intubation or supraglottic airway, waveform capnography, and tube securing per protocol |
| RN (ED/ICU) | Tube maintenance, cuff-pressure checks, reassessment after movement, and ventilator support |
| Critical care transport | Ventilator settings, tube security during transport, and pumps and infusions |
- Equipment: Bag-mask devices in three sizes, OPA and NPA, suction in the right French size, tubes ±0.5 mm, a stylet, and capnography.
- Heat loss: Infants lose heat fast. Cover the head and use warm blankets.
- Restraint: Use a restraint sized for the child on the stretcher. A child never rides on a caregiver's lap during transport.
- CCT ventilation: Starting tidal volume and PEEP are protocol-dependent (commonly about 6–8 mL/kg and PEEP about 5 cmH₂O, not guideline values here); rate by age, adjusted to capnography and SpO₂.
- Handoff: Give it in IMIST-AMBO or MIST. Include the tube size, the depth and the last capnography reading.
Clinical Pearls
"If you can ventilate, you can wait": Effective bag-mask ventilation buys time. If it is working, spend that time improving conditions before the next attempt. Call for help. Position the child. Set up video laryngoscopy if it is available, and have a backup airway ready. Keep the mask seal and jaw thrust in place while you prepare.
Quiet can mean tiring: A child in respiratory distress who was crying and then suddenly goes quiet may be tiring. Less work of breathing without clinical improvement is more dangerous than ongoing distress. Reassess color, air entry and mental status right away. Ask the caregiver how the child normally breathes.
Plan for one half-size either way: Formulas are estimates, so plan for error. Prepare the calculated cuffed tube, one half-size smaller and one half-size larger. Resistance below the cords means go smaller. A leak after the cuff is checked means go larger.
Anatomy changes with age, not just weight: Two children of the same weight can have different airway sizes. Choose the tube by age or length. Confirm the position with waveform capnography, not the depth mark alone.
References
- 2025 AHA Guidelines for CPR and ECC, Part 8: Pediatric Advanced Life Support. American Heart Association and American Academy of Pediatrics. Circulation. 2025:S479–S537. https://doi.org/10.1161/CIR.0000000000001368 https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/pediatric-advanced-life-support
- 2025 AHA Guidelines for CPR and ECC, Part 6: Pediatric Basic Life Support. American Heart Association and American Academy of Pediatrics. Circulation. 2025:S424–S447. https://doi.org/10.1161/CIR.0000000000001370 https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/pediatric-basic-life-support
- 2025 AHA Guidelines for CPR and ECC, Part 5: Neonatal Resuscitation. American Heart Association and American Academy of Pediatrics. Circulation. 2025:S385–S423. https://doi.org/10.1161/CIR.0000000000001367 https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/neonatal-resuscitation
- Weiss M, Dullenkopf A, Fischer JE, Keller C, Gerber AC; European Paediatric Endotracheal Intubation Study Group. Prospective randomized controlled multi-centre trial of cuffed or uncuffed endotracheal tubes in small children. Br J Anaesth. 2009;103(6):867–873. https://doi.org/10.1093/bja/aep290 (Landmark trial.)
- Khine HH, Corddry DH, Kettrick RG, Martin TM, McCloskey JJ, Rose JB, Theroux MC, Zagnoev M. Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology. 1997;86(3):627–631. https://doi.org/10.1097/00000542-199703000-00015 (Landmark trial.)
- Litman RS, Weissend EE, Shibata D, Westesson PL. Developmental changes of laryngeal dimensions in unparalyzed, sedated children. Anesthesiology. 2003;98(1):41–45. https://doi.org/10.1097/00000542-200301000-00010 (Landmark study.)
- Kim DK, Kim JT, Na JY, et al. 2025 Korean Guidelines for Cardiopulmonary Resuscitation: Part 8. Pediatric advanced life support. Clin Exp Emerg Med. 2026;13(suppl 1):S115. doi:10.15441/ceem.26.103. https://pmc.ncbi.nlm.nih.gov/articles/PMC13277418/
- All India Difficult Airway Association. All India Difficult Airway Association 2025 guidelines for the management of unanticipated difficult airway in paediatrics under general anaesthesia. Indian J Anaesth. 2025. doi:10.4103/ija.ija_1096_25. https://pmc.ncbi.nlm.nih.gov/articles/PMC12643152/
Medical Disclaimer
- For Educational Purposes Only: This content is intended for educational reference and should not be used for clinical decision-making.
- Not a Substitute for Professional Judgment: Always consult your local protocols, institutional guidelines, and supervising physicians.
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