Paediatric airway differences

Surgical approach

• Not an operation: no specific surgical steps.
  • Relevant surgical airway options in children (rare): needle cricothyroidotomy / transtracheal oxygenation, surgical tracheostomy (ENT).

Anaesthetic management (context: airway instrumentation in children)

• Type of anaesthesia: usually GA (inhalational or IV induction depending on aspiration risk, cooperation, airway difficulty).
• Airway device: facemask → SGA or ETT depending on procedure, aspiration risk, ventilation needs, and airway pathology.
  • ETT: cuffed microcuff commonly used; uncuffed still acceptable in some settings with careful leak/fit.
• Duration: variable (minutes to hours) depending on surgery; airway differences matter most during induction, positioning, and emergence.
• How painful: airway instrumentation itself is stimulating; ensure adequate depth, topicalisation rarely used in small children; consider opioids/paracetamol/NSAID as per surgery.
• Key priorities: oxygenation, gentle technique, appropriate sizing, minimising airway trauma/oedema, anticipating rapid desaturation.

Core anatomical differences (infant/child vs adult) and implications

• Head/occiput: relatively large occiput in infants → natural neck flexion when supine.
  • Implication: may need shoulder roll (not head pillow) to achieve neutral/sniffing alignment; avoid excessive flexion causing obstruction.
• Tongue: proportionally larger in smaller mandible.
  • Implication: obstruction during sedation/induction; jaw thrust/oropharyngeal airway often helpful; careful with OPA sizing to avoid trauma.
• Nasal passages: narrow; infants are preferential nasal breathers (especially < 6 months).
  • Implication: minor oedema/secretions markedly increase resistance; gentle suction, humidification; consider decongestant for nasal instrumentation.
• Larynx position: higher and more anterior (approx C3–4 in neonate vs C4–5 child, C5–6 adult).
  • Implication: laryngoscopy can be more challenging; straight blade often useful to directly lift epiglottis.
• Epiglottis: relatively long, narrow, omega/U-shaped, and more floppy.
  • Implication: may obscure view; straight blade (Miller) to lift epiglottis; avoid excessive force/trauma.
• Vocal cords: angled and more anterior; glottic opening smaller.
  • Implication: ETT passage may meet resistance at cords/subglottis; rotate tube, use appropriate size, consider smaller tube rather than force.
• Narrowest point: functionally often at cricoid/subglottis in infants/young children; even with cuffed tubes, subglottis is a key limiting area.
  • Implication: risk of post-intubation croup/stridor from mucosal injury; choose correct size, minimise attempts, ensure leak at safe pressure if uncuffed, monitor cuff pressure if cuffed.
• Trachea: shorter and narrower; carina more easily reached; right main bronchus less vertical difference than adults but still more likely for endobronchial intubation.
  • Implication: small changes in head position can move ETT significantly; secure well; re-check after positioning; beware endobronchial intubation and accidental extubation.
• Airway mucosa: more delicate; oedema develops easily.
  • Implication: atraumatic technique, limit suctioning, humidify gases, consider dexamethasone for airway swelling risk (e.g., multiple attempts, ENT surgery).

Physiological differences relevant to airway management

• Higher oxygen consumption (VO2) and lower FRC → rapid desaturation during apnoea.
  • Implication: optimise preoxygenation (tight mask seal, CPAP/PEEP if needed), minimise apnoea time, early use of two-person mask ventilation.
• Airway resistance: small radius → resistance increases dramatically with oedema/secretions (Poiseuille).
  • Implication: treat nasal congestion/secretions; consider bronchodilator if reactive airway; gentle handling to avoid swelling.
• Chest wall/lung mechanics: compliant chest wall, less compliant lungs; diaphragmatic breathing predominates; fatigue occurs quickly.
  • Implication: obstruction increases work of breathing markedly; early support/CPAP; avoid prolonged struggling during induction.
• Control of ventilation: immature respiratory drive in neonates; apnoea risk (especially ex-prem, sepsis, opioids).
  • Implication: careful opioid dosing, consider postoperative monitoring; avoid hypothermia and hypoglycaemia which worsen apnoea.

Practical implications: positioning, mask ventilation, laryngoscopy

• Positioning: aim for neutral alignment in infants (shoulder roll) and sniffing in older children; ensure external auditory meatus–sternal notch alignment as a guide.
• Mask ventilation: common difficulty is upper airway obstruction (tongue/soft tissues).
  • Use two-person technique early; jaw thrust; appropriately sized OPA/NPA (NPA with caution in coagulopathy/basal skull fracture).
  • Apply PEEP/CPAP to prevent atelectasis and improve oxygenation; avoid excessive pressures to reduce gastric insufflation.
• Laryngoscopy: straight blade often improves view in infants; video laryngoscopy increasingly used but requires appropriate blade size and familiarity.
• Cricoid pressure: evidence limited; can worsen laryngoscopic view and mask ventilation; if used, apply gently and release if impedes ventilation/intubation.

ETT/SGA selection and sizing (high-yield)

• SGA: useful for many short, low aspiration-risk cases; can be a rescue for difficult mask ventilation; ensure correct size and depth of anaesthesia to avoid laryngospasm.
• ETT choice: cuffed tubes widely used; advantages include better seal, more reliable ventilation/ETCO2, reduced need for tube changes.
  • Key: monitor cuff pressure (aim low; typically ≤ 20–25 cmH2O) to reduce mucosal injury.
• Sizing (common exam formulae):
  • Uncuffed ETT internal diameter (mm) ≈ (age/4) + 4.
  • Cuffed ETT internal diameter (mm) ≈ (age/4) + 3.5.
  • ETT depth (oral, cm) ≈ (age/2) + 12 (rough guide) OR 3 × ETT ID (mm). Confirm with ETCO2 + auscultation + fibreoptic/US if needed.
• Tube too large signs: resistance passing, no leak at 20–25 cmH2O (if uncuffed), high airway pressures, post-extubation stridor.
  • Management: downsize rather than force; consider dexamethasone/nebulised adrenaline if stridor.

Laryngospasm and airway reactivity (paediatric emphasis)

• Children have higher risk of laryngospasm (URTI, airway surgery, secretions, light anaesthesia, stimulation).
• Prevention: adequate depth, gentle suctioning, consider deep vs awake removal depending on risk/experience, treat reflux/secretions, avoid airway irritation.
• Management (sequence): remove stimulus, jaw thrust + CPAP 100% O2, deepen anaesthesia (propofol), then suxamethonium if persistent (with atropine/rocuronium alternative depending on context).
  • Be prepared for rapid desaturation and negative pressure pulmonary oedema if prolonged obstruction.

Difficult airway considerations unique to children

• Lower tolerance of apnoea + smaller margins for error → prioritise oxygenation and early call for help.
• Front-of-neck access: cricothyroid membrane is small and difficult; surgical cricothyroidotomy is generally avoided in small children; needle techniques/tracheostomy by ENT more common.
  • Implication: plan to avoid CICO; optimise mask/SGA strategies; have age-appropriate equipment and a clear escalation plan.
• Common congenital causes: Pierre Robin sequence, Treacher Collins, craniosynostosis syndromes, subglottic stenosis, laryngomalacia, vascular rings.