• Basic principles of neonates and infants
    • Respiratory
      • Surfactant production begins at 30-32 weeks
      • A birth, only have 10% of adult numbers of alveoli
      • Ribs extend horizontally so diaphragm more important but less efficient
      • Less fatigue resistant T1 muscle fibres in diaphragm
      • Tidal volume relatively fixed so inc RR is the only way to increase alveolar ventilation
      • Lungs stiff at birth but compliance increases dramatically over the first few hrs
      • Low FRC and high closing capacity can lead to shunt
      • High oxygen consumption 6-7 ml/kg/min
    • Anatomical variations
      • Large head, short neck
      • Obligatory nasal breathers
      • Large tongue
      • Large occiput
      • High larynx (C3/4)
      • Trachea only about 5cm
      • Narrowest part at cricoid
      • Long epiglottis
    • CNS
      • 350g at birth, doubles in 6/12
      • Myelination up to 3yrs
      • IVH commoner due to thin walled cerebral vessels
      • Immature BBB
      • Impaired autoregulation
    • Thermoregulation
      • Large surface area:volume ratio
      • NST by brown fat
      • Unable to shiver
    • Pharmacology
      • Generally, uptake and distribution is increased and elimination decreased so high risk of toxicity
      • High c.o. so fast distribution
      • Large ECF so influences Vd
      • Low α-1 acid glycoprotein levels cause low protein binding
      • Reduced phase 1 & phase 2 reactions
      • Renal function is reduced in the newborn
      • Inhalational
        • MAC lower in preterms
        • Maximal at 6/12
        • Wash-in quick due to high alveolar ventilation in relation to FRC, greater fraction of c.o. to vessel rich organs
      • IV agents
        • Barbituates and ketamine safe
        • Increased sensitivity to barbituates
      • Muscle relaxants
        • NMJ more sensitive but higher Vd so dose unchanged
        • Immature liver so sux takes longer to metabolise
    • Post-op apnoea
      • Commoner in post-conceptual age of <60 weeks
      • Peaks if PCA of <44 wks
    • Cardiovascular
      • RV wall is thicker than left at birth so there is RAD
      • Equilibration at 3-6 months
      • Sarcomeres less dense in newborns
      • Less compliant LV with fixed SV so c.o. is dependent on HR
      • Parasympathetic tone predominates and bradycardia can be precipitated
      • Circulating volume is small so modest blood loss can cause hypovolaemia
      • Hypotension usually indicates hypovolaemia
      • Risk of hypoglycaemia
      • ECF exceeds ICF at birth. This changes during infancy
    • CEACCP
      Link:ceaccp.oxfordjournals.org/content/1/5/130.full.pdf?sid=a268f578-8d7b-4baf-a260-43d9ad1e21ec