The airway begins to develop from the primitive foregut at 4 weeks' gestation. Congenital
anomalies may result when this process is abnormal. The anatomy of the airway at birth
is uniquely different from older children and adults with a large tongue, long floppy
epiglottis, large occiput, cephalad larynx, and narrow cricoid cartilage. These features
affect the technique required for endotracheal intubation and facemask ventilation.
A neutral head position and straight bladed laryngoscope are usually used. Neonates
are also obligate nasal breathers and simultaneously suckle and breathe. Minute volume
is rate-dependent and the highly compliant chest easily displays sternal and intercostal
recession during respiratory distress, and early onset of fatigue. From the neonatal
period onwards the anatomy gradually begins to resemble that of adults. The cricoid
descends caudally, the epiglottis becomes firmer and shorter, and the large occiput
recedes. By 8–10 years the airway is anatomically adult in most ways other than absolute
size. The ‘sniffing the morning air’ and curved laryngoscope become appropriate for
endotracheal intubation. Conventionally, uncuffed endotracheal tubes have been used
in children; however high volume-low pressure cuffed tubes are now available, allowing
monitoring of the cuff pressure intermittently throughout use.