Anaes · Paediatric anaesthesia
Paediatric respiratory and cardiovascular physiology for the anaesthetist
Also known as Infant cardiovascular physiology · Paediatric FRC oxygen consumption · Neonatal transitional circulation anaesthesia
Infant oxygen consumption, FRC and closing capacity, compliant chest wall, heart-rate-dependent cardiac output, transitional circulation residues, thermoregulation, and the anaesthetic implications that explain rapid desaturation and hypoxic bradycardia for ANZCA Primary and Final.
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Red flags
- Bradycardia in an infant is cardiac output failure until proven otherwise — oxygenate and stimulate first.
- Apnoea risk in ex-preterms after anaesthesia tracks post-menstrual age, not chronological age alone.
- Hypothermia worsens oxygen consumption, coagulopathy, and respiratory drive — active warming is mandatory.
- Horizontal ribs and a highly compliant chest wall make abdominal distension a real ventilatory emergency.
- Hypoxia, hypercarbia, and acidosis can reopen transitional shunts and recreate PPHN physiology.
Meet the patient
A six-week-old for pyloric stenosis repair desaturates from 99 to 82 within 30 seconds of apnoea after induction. Heart rate falls from 140 to 70. The registrar reaches for atropine — but the first move is oxygen, not a drug.[7][8]
This is applied infant physiology in action: high oxygen consumption empties the small FRC store in seconds, closing capacity encroaches on FRC so airways close and shunt develops, and hypoxia drives bradycardia that collapses cardiac output because stroke-volume reserve is limited (taught). Every paediatric airway plan is also a cardiac output plan — every neonatal intubation is a critical event with passive oxygenation.[7]
References10ShowHide
- [1]Davidson AJ, Disma N, de Graaff JC, et al. Neurodevelopmental outcome at 2 years of age after general anaesthesia and awake-regional anaesthesia in infancy (GAS): an international multicentre, randomised controlled trial Lancet, 2016.PMID 26507180
- [2]McCann ME, de Graaff JC, Dorris L, et al. Neurodevelopmental outcome at 5 years of age after general anaesthesia or awake-regional anaesthesia in infancy (GAS): an international, multicentre, randomised, controlled equivalence trial Lancet, 2019.PMID 30782342
- [3]Flick RP, Wilder RT, Pieper SF, et al. Risk factors for laryngospasm in children during general anesthesia Paediatr Anaesth, 2008.PMID 18315633
- [4]Coté CJ, Zaslavsky A, Downes JJ, et al. Postoperative apnea in former preterm infants after inguinal herniorrhaphy. A combined analysis Anesthesiology, 1995.PMID 7717551
- [5]Sikich N, Lerman J Development and psychometric evaluation of the pediatric anesthesia emergence delirium scale Anesthesiology, 2004.PMID 15114210
- [6]Di Cicco M, et al. Structural and functional development in airways throughout childhood: Children are not small adults. Pediatr Pulmonol, 2021.PMID 33179415
- [7]Garcia-Marcinkiewicz AG, Matava CT Safe in the first attempt: teaching neonatal airway management Curr Opin Anaesthesiol, 2022.PMID 35671020
- [8]Binkhorst M, et al. Threshold to initiate chest compressions for bradycardia at birth: A narrative review J Perinatol, 2025.PMID 40360699
- [9]Somayaji S, Karanth N, Ganigara A, et al. Comparison of non-hypoxic apnea time in infants during induction of anesthesia with or without PEEP J Anaesthesiol Clin Pharmacol, 2026.PMID 41542213
- [10]Al-alami AA, et al. Pediatric laryngospasm: prevention and treatment Curr Opin Anaesthesiol, 2009.PMID 19434787