Neonates have difficult upper airways that are prone to collapse, as well as less favorable respiratory mechanics, altered O2 transport, and immature control of breathing.
More difficult to intubate:
Small mandible
Large tongue
Larger tonsils and adenoids
Superior laryngeal position
Large, floppy epiglottis
Anatomical subglottic narrowing
Soft, narrow, short trachea
Mechanics
Resistance: higher (smaller airways)
Compliance: lower lung compliance (less surfactant), higher chest wall compliance (not ossified)
Higher WOB, minimal WOB at respiratory rate 40
Volumes
Specific FRC is unchanged
Closing capacity is increased (less radial tension on airways)
Anatomical dead space is increased (big heads, small chests)
Gas transport
Increased shunt due to ductus arteriosus
Left-shifted HbODC due to HbF
Higher [Hb] to compensate
Control of breathing
Decreased response to hypoxia and hypercapnoea
Periodic apnoeas