Child and adult physiological differences

• Pediatric age group


  • Presents anesthetists to challenges through perioperative period
  • Differences in airway anatomy, chest wall and respiratory function
  • Differences in cardiovascular function
• Larger volume of distribution


  Due to greater total body water than adults
• Kidneys and liver are still immature


  • Kidneys are less efficient prolonging drugs half life
  • Hepatic drug metabolism is also decreased in neonates
• Airway Anatomy


  • Large head with prominent occiput
  • Large tongue
  • Preferential nose breather
  • Glottic opening at level of C4
  • Long epiglottis can flop posteriorty
  • Narrowest segment of the airway is subglottic
• Airway Management


  1. Position head and neck to maintain in a neutral position

  2. Maintain patent nasal passages

  3. Consider small endotracheal tube to minimize postextubation stridor

  4. Position endotracheal tube to avoid inadvertent extubation or endobronchial intubation with head movement
• Chest wall anatomy and pulmonary physiology

  • Compliant chest wall
  • Rate dependant ventilation
  • Work of breathing may exceed 15% of oxygen delivery
  • Fewer alveoli (10% of adult)
  • Frequent post operative apneas in premature infants
  • Ventilation is primarily from the diaphragm
• Airway Management


  1. Rapid hypoxia during induction despite pre-oxygenation

  2. Empty stomach

  3. Gentle bag mask ventilation

  4. Post-operative monitoring
• Cardiovascular system


  • Fixed stroke volume
  • Cardiac output is heart rate dependent
  • High vagal tone
• Cardiovascular Management


  Treat neonates with heart rate <100 beats/min with restoration of oxygenation and epinephrine 10 ug/kg
• Immature renal function


  • Large surface area relative to weight
  • Larger extracellular volume
• Volume status Management


  Maintain urine output 2-1 mL/kg
• Decreased opioid metabolism


  Prolonged opioid effect
• Metabolism


  • Limited glycogen reserves
  • Immature thermoregulation
• Metabolism Management


  1. Glucose infusion in neonates at risk

  2. Consider techniques to increase core body temperature
• Central nervous system


  • Immature blood brain barrier
  • Opioids and antibiotics easily cross the blood brain barrier
• Central nervous system Management


  Cautios dose of opioids