Anaesthesia Plan: 3-Year-Old, 10 kg Child

1. Preoperative Assessment

• ASA classification, full history including birth history, prior anaesthesia, family history of MH or pseudocholinesterase deficiency
• Airway assessment: look for syndromes associated with difficult airway (Pierre Robin, Down syndrome, Treacher Collins). At 3 years, the airway is maturing but still differs from adults - large occiput, large tongue relative to oral cavity, anterior larynx, narrowest point at subglottis
• Recent URTI: if active URTI with productive cough or fever, consider deferring 2-4 weeks (increased PRAEs - laryngospasm, bronchospasm, oxygen desaturation)
• Nil-by-mouth status: clear fluids up to 1 hour before, breast milk 4 hours, formula/solids 6 hours (2023 revised fasting guidelines used at many centres; confirm local policy)
• Haemoglobin if significant blood loss expected

• ETT size: uncuffed = age/4 + 4 = 4.0 mm (or cuffed 3.5 mm); confirm with depth = (age/2 + 12) = ~13-14 cm at lips
• LMA size: LMA #2 (suitable for 10-20 kg)
• Blood pressure cuff: small child size

2. Premedication

• Midazolam oral: 0.3-0.5 mg/kg PO (max 15 mg), ~30 min before induction - effective anxiolysis for a 3-year-old who is likely in "stranger anxiety" developmental stage
• Alternatively: dexmedetomidine intranasal 1-2 mcg/kg if IV access already in place or oral route not feasible
• Paracetamol (acetaminophen) oral: 15 mg/kg = 150 mg PO as premedication for multimodal analgesia
• EMLA/Ametop cream over potential IV sites (dorsum of hand) if IV induction planned

3. Induction

• Sevoflurane is the agent of choice: pleasant smell, non-pungent, rapid wash-in due to low blood-gas solubility, cardiovascular stability
  • Start at 8% sevoflurane in 100% O₂ using a well-fitting mask with flavouring
  • Reduce to 4-6% once unconscious
  • MAC for sevoflurane in a 3-year-old ≈ 2.5% (higher than adults)
  • Wash-in is faster in children than adults (higher alveolar ventilation-to-FRC ratio, greater VRG perfusion)
  • Once IV access secured (large antecubital or dorsal hand vein), transition to IV agents as needed

• Propofol IV: 3.5-5.4 mg/kg (ED90 for LMA insertion = 5.4 mg/kg) = 35-54 mg; the 50% higher dosing compared to adults is required in young children to achieve target brain concentration of ~3 mcg/mL
• For tracheal intubation: Propofol 1-2 mg/kg with sevoflurane, or add fentanyl 1-2 mcg/kg (= 10-20 mcg) to blunt intubation response

• Atracurium 0.5 mg/kg IV = 5 mg (preferred in children - spontaneous non-enzymatic Hofmann elimination, no organ dependence)
• Or rocuronium 0.6 mg/kg = 6 mg (reversible with sugammadex 16 mg/kg for RSI dose)
• Avoid suxamethonium routinely in children - risk of hyperkalaemia from undiagnosed myopathies (e.g., Duchenne MD); reserve for RSI or laryngospasm emergency
• Suxamethonium RSI dose: 2 mg/kg IV (= 20 mg) if RSI specifically indicated

4. Airway Management

• LMA size 2 (10-20 kg) is appropriate for most elective procedures; allows spontaneous ventilation and avoids risks of intubation
• ETT if required (head and neck, abdominal, laparoscopic, RSI, or prolonged procedure):
  • Cuffed ETT 3.5 mm (preferred by most modern guidelines to allow low leak pressures and reduce repeated laryngoscopy)
  • Uncuffed ETT 4.0 mm if no cuffed available
  • Confirm position with capnography and bilateral breath sounds
  • Aim leak pressure 15-25 cmH₂O if using uncuffed tube
• Laryngoscope: Straight blade (Miller 1 or Macintosh 1) - useful in younger children to elevate floppy epiglottis
• Head position: Neutral to slight sniffing (avoid overextension - can obstruct the relatively anterior paediatric larynx)
• Stylet/bougie and smaller ETT (3.5 uncuffed, 3.0) readily available

5. Maintenance of Anaesthesia

• Sevoflurane 2-3% in O₂/air (or O₂/N₂O if N₂O used - though avoidance of N₂O recommended on environmental grounds per Barash 43, p.3699)
• Target MAC 1.0-1.2 adjusted for procedure stimulation
• Desflurane is avoided in children: causes airway irritability and is a potent greenhouse gas

• Propofol infusion: Initial rate 15 mg/kg/hr (250 mcg/kg/min) for sedation/TIVA, titrated down; maintenance typically 6-12 mg/kg/hr once steady state
• Plus remifentanil infusion 0.05-0.3 mcg/kg/min for analgesia and blunting of reflexes

• Ondansetron 0.1 mg/kg IV = 1 mg (max 4 mg) - prophylaxis if high PONV risk (ENT, strabismus, opioids)
• Dexamethasone 0.15 mg/kg IV = 1.5 mg - dual role: antiemetic + reduces emergence delirium

6. Fluid Management

• For 10 kg: 100 mL/kg/day = 100 mL/hr first 10 kg = ~42 mL/hr

• Balanced crystalloid (Hartmann's/Ringer's lactate or PlasmaLyte) preferred
• Avoid glucose-containing solutions routinely (risk of hyperglycaemia), unless fasting >8 hours or neonates
• Replace third-space losses based on procedure

• Hb transfusion trigger generally 7-8 g/dL in healthy children (lower in cardiac disease)
• Estimated blood volume (EBV) for 3-year-old = ~75 mL/kg = 750 mL

7. Monitoring (AAGBI minimum standards)

• SpO₂ (pulse oximetry)
• Capnography (ETCO₂) - mandatory when airway secured
• ECG
• NIBP every 3-5 min
• Temperature (children are prone to hypothermia - warm room, warm fluids, Bair Hugger/forced air warming, warm IV fluids)
• Peripheral nerve stimulator if neuromuscular blockade used

8. Emergence & Recovery

• Emergence delirium is common in 2-5 year olds: prevention with dexmedetomidine 0.3-0.5 mcg/kg IV at end of case, or with TIVA (propofol reduces incidence vs. volatile)
• Extubate either awake (preferred in full stomach, airway surgery) or deep (less coughing/laryngospasm for routine cases) - institutional and clinical decision
• Laryngospasm is the most feared PRAE at emergence: treat with CPAP, jaw thrust, propofol 0.5 mg/kg IV; have suxamethonium 2 mg/kg ready (20 mg)
• Stridor post-extubation: nebulised adrenaline 0.5 mL/kg of 1:1000 (max 5 mL), dexamethasone 0.6 mg/kg

• Standard monitoring, supplemental O₂
• Pain assessment with FLACC score
• Oral paracetamol/NSAID for breakthrough pain

9. Emergency Drugs (pre-drawn, labelled)

10. Key Paediatric-Specific Pitfalls

1. Rapid desaturation - small FRC relative to oxygen demand; pre-oxygenate well (THRIVE/high-flow if available for anticipated difficult airway)
2. Hypothermia - high surface area:body mass ratio; actively warm from pre-induction
3. Bradycardia - cardiac output is heart-rate dependent in young children; have atropine ready
4. Laryngospasm - peak incidence 2-6 years; URTI increases risk 10-fold
5. Drug dosing errors - always calculate per kg before drawing up; use a weight-based reference card
6. Undiagnosed myopathy - avoid routine suxamethonium; treat unexplained masseter spasm or tachycardia as MH until proven otherwise