For instance, helium is less dense than nitrogen and slightly more viscous,
thereby increasing the chance of laminar flow. This accounts for why Heliox
(helium and oxygen mix) being useful in upper airway problems such as croup,
stridor where upper airway problems predominate. in contrast, Heliox does not
work in status asthmaticus.
Venturi effect – flow of gas increases as it flows through a partially obstructed tube.
Bernoulli effect – increase on velocity associated with decrease in pressure.
3.Anatomic considerations:Children have large tongues relative to their oral cavities and the tongues
easily occlude the palate because it has less forward displacement In addition, the
larynx is cephalad (located at the region of C2-C3) compared to adults (larynx is at
C4-C5). The airway in a child is funnel shaped, where the narrowed portion is the
cricoid cartilage, which is circular-shaped. In comparison, adults have a trapezoid
shaped laryngeal apex. Intubation in children should align oral opening,
pharyngeal and laryngeal opening.
A child’s epiglottis is long and narrow compared to adults.Practical points: Use Miller tubes versus MAC tubes. Children have large
heads and bumping the shoulder may help in aligning the planes.
II. Controlling the Airway