Key Facts

Paediatric anaesthesia is a subspecialty requiring specific training and expertise. Children have higher metabolic rates, different airway anatomy, and age-dependent pharmacokinetics that influence drug dosing and monitoring.

Epidemiology

Approximately 500,000 paediatric anaesthetics are administered annually in the UK. Perioperative cardiac arrest in children occurs in approximately 1 in 10,000 anaesthetics (higher than adults). The highest risk is in neonates and infants under 1 year.

Aetiology

Key anatomical differences in children:

• Airway: Large head/occiput, large tongue, high anterior larynx (C3 vs C5), epiglottis long and floppy, narrow subglottis (narrowest part in children vs glottis in adults)
• Respiratory: Fewer alveoli, compliant chest wall, horizontal ribs, diaphragmatic breathing, higher closing volume
• Cardiovascular: Heart rate-dependent cardiac output, limited contractile reserve
• Thermoregulation: High surface area:volume ratio → rapid heat loss
• Pharmacological: Larger volume of distribution, immature hepatic/renal function in neonates, higher MAC requirement

Pathophysiology

Neonates and infants are particularly vulnerable to hypoxia, hypothermia, and hypoglycaemia. Their limited respiratory reserve (FRC close to closing volume) means rapid desaturation during apnoea. Cardiac output is heart rate-dependent with limited stroke volume reserve. Immature hepatic metabolism prolongs the action of many drugs in neonates.

Age-Related Considerations

• Neonate (0-28 days): Highest risk; transitional circulation, immature systems
• Infant (1-12 months): Rapid growth, high metabolic rate
• Pre-school (1-5 years): Separation anxiety, uncooperative
• School age (5-12 years): Generally cooperative, can understand explanations
• Adolescent (12-18 years): Approaching adult physiology

Common Paediatric Procedures

• Myringotomy/grommets, tonsillectomy/adenoidectomy
• Circumcision, inguinal hernia repair
• Orthopaedic (fracture reduction)
• Dental extractions
• Neonatal surgery (NEC, TOF, CDH)

Red Flags

• Stridor in a child — potential airway emergency (croup, epiglottitis, foreign body)
• Active URTI with fever, productive cough — postpone elective surgery 2-4 weeks (increased airway reactivity)
• Ex-premature infant <60 weeks post-conceptual age — risk of post-operative apnoea
• Difficult IV access in a dehydrated/shocked child — use intraosseous (IO) access

Bedside

• Weight: Essential for drug dosing (estimated by age-based formulae if unable to weigh: APLS weight = (age+4) × 2 for 1-5yr)
• Airway assessment: Age-appropriate assessment
• Observations: HR, RR, SpO2, BP (age-appropriate cuff)
• Blood glucose: Especially neonates and infants

Bloods

• FBC: If anaemia suspected or blood loss expected
• Group and save: If blood loss anticipated
• U&Es: If renal disease, dehydration, or IV fluid therapy needed
• Sickle cell screen: In at-risk populations
• Blood glucose: Neonates, infants, diabetic children

Imaging

• CXR: Not routine; only if respiratory symptoms or neonatal pathology

Special Tests

• Echocardiography: If congenital heart disease suspected
• Sleep study: If OSA suspected (tonsillectomy patients)

Non-pharmacological

• Parental presence: At induction — reduces anxiety
• Play specialist: Preparation and distraction
• EMLA/Ametop cream: Applied 45-60 minutes before for painless cannulation
• Fasting: 6h solids, 4h breast milk, 1h clear fluids (1-4-6 rule)
• Temperature management: Warm theatre (26°C for neonates), warming mattress, hat, forced-air warmer, warm fluids

Pharmacological

• Inhalational induction: Sevoflurane 8% in O2 (standard paediatric induction)
• IV induction: Propofol 3-4mg/kg (higher dose than adults)
• Maintenance: Sevoflurane 2-3% in O2/air; or TIVA
• Analgesia: Paracetamol 15mg/kg PO/IV QDS + ibuprofen 5mg/kg TDS + morphine 0.1mg/kg IV PRN; caudal block (bupivacaine 0.25% 0.5-1mL/kg) for sub-umbilical surgery
• Suxamethonium: 2mg/kg IV in children (higher dose due to larger Vd); 4mg/kg IM if no IV access
• Atropine 20mcg/kg: Pre-treat before suxamethonium in children (vagal response more common)
• Emergence agitation prophylaxis: Fentanyl 1mcg/kg or dexmedetomidine 0.5mcg/kg

Surgical/Interventional

• Caudal epidural: Most common regional technique in paediatric anaesthesia (sacral approach)
• Peripheral nerve blocks: USS-guided, similar to adults but weight-based dosing

Referral Criteria

• Neonatal surgery — specialist paediatric anaesthetic centre
• Congenital heart disease — specialist paediatric cardiac centre
• Ex-premature infants <60 weeks post-conceptual age — specialist centre with apnoea monitoring
• Suspected malignant hyperthermia — TIVA, specialist centre

• Perioperative cardiac arrest: ~1 in 10,000 paediatric anaesthetics (higher in neonates)
• Laryngospasm: Occurs in ~1-3% of paediatric anaesthetics — usually managed with basic manoeuvres
• Post-operative apnoea: Risk in ex-premature infants — monitor for 12-24h post-operatively
• Neurotoxicity concerns: Animal evidence of volatile/propofol neurotoxicity in developing brain; GAS and PANDA trials showed no significant neurodevelopmental difference after single brief anaesthetic in infants
• Long-term outcomes: Paediatric anaesthesia is very safe with appropriate training and equipment

Paediatric Equipment Sizing

Paediatric Fluid Management

Common Drug Doses (Paediatric)