Definition
Turbulent gas flow increases with increasing gas density and gas flow rate.
- Decreasing gas density with heliox (molecular weight 9.6) instead of air (molecular weight 29) to ventilate patients helps to relieve airway obstruction e.g. in tracheal stenosis.
- Decreasing gas flow rate, as in taking slower deep breaths, also helps to ventilate patients with airway obstruction in larger airways e.g. tracheal stenosis (remember that disease of peripheral airways such as emphysema or cystic fibrosis contribute little total airway resistance since the total cross-sectional area of small airways is very large and flow there is laminar).
In contrast, laminar flow (for fluid dynamics or airway resistance) depends on the viscosity of the blood as described by Poiseuille’s law [resistance = (8 * length * viscosity) / (pi * r^4)].
Subspecialty
Related Media
Keyword history
71%/2009
See Also:
Sources
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Barash PG, Cullen BF, Stoelting RK, Cahalan M, Stock MC, eds. Clinical Anesthesia, 6th ed. Philadelphia, PA: Lippincott, Williams and Wilkins; 2009: 238
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Davis PJ, Cladis FP, Motoyama EK (eds). Smith’s Anesthesia for Infants and Children, 8th ed. Philadelphia, PA: Elsevier Mosby; 2011: 49, 70