Paediatric respiratory and cardiovascular physiology for the anaesthetist

Model answer

Respiratory (6). Greater oxygen consumption with high minute ventilation relative to a small functional residual capacity, plus increased closing volumes — after a missed airway attempt this combination rapidly turns dire, even to arrest. Resting VO2 is more than double adult; infants are nasal breathers at 2-6 mo with subglottic/cricoid narrowest points. Treat every infant intubation as a critical event; use passive oxygenation.^[1][3]

Cardiovascular (5). Bradycardia means ventilate: guidelines escalate to chest compressions only if heart rate stays below 60 after 30 s of ventilation (expert-opinion/scant-animal basis, no comparative trials), and most surveyed clinicians (74.9%) prioritise effective ventilation first with reconsideration argued.^[2]

Implications (4). Preoxygenate, limit apnoea time, treat bradycardia as an emergency, and monitor ex-preterms by postconceptual age (not <5% apnoea risk until 48 wk, not <1% until 56 wk).^[1][2][4]