We evaluated the resistance to gas flow in vitro in regular and trimmed endotracheal tubes of different size and in several commercially available nasal CPAP devices of different size. The highest resistance—141 cm H2O/L/s at 6 L/min flowrate and 92 cm H2O/L/s at 3 L/min—was present in the longest nasal device (6.0 cm) with the smallest diameter (ID, 1.7 mm; OD, 2.5 mm). Of the shorter nasal devices (0.5-1.0 cm), the one with the largest diameter (ID, 3.0 mm; OD, 5.5 mm) had the lowest resistance—11 cm H2O/L/s at 6 L/min flowrate and 8 cm H2O/L/s at 3 L/min. The resistance present in most devices was similar to the natural resistance in the upper airway and, therefore, should have minimal impact on the work of breathing.
Get full access to this article
View all access options for this article.
References
1.
GregoryGA, KittermanJA, PhibbsRH, TooleyWH, HamiltonWK. Treatment of the idiopathic respiratory distress syndrome with continuous positive airway pressure. N Engl J Med1971;284:1333–1340.
2.
AgostinoR, OrzulesiM, NodariS, et al. Continuous positive airway pressure (CPAP) by nasal cannulae in the respiratory distress syndrome (RDS) of the newborn (abstract). Pediatr Res1973;7:50.
3.
CaveP, FletcherG.Resistance of nasotracheal tubes used in infants. Anesthesiology1968;29:588–590.
4.
KattwinkelJ, FlemingD, ChaC, et al. A device for administration of continuous positive airway pressure by the nasal route. Pediatrics1973;52:131–134.
5.
DoershukCF, MatthewsLW. Airway resistance and lung volume in the newborn infant. Pediatr Res1969;3:128–134.
6.
ShapiroBA, HarrisonRA, TroutCA. Clinical application of respiratory care. Chicago: Year Book Medical Publishers Inc, 1979:57.
7.
PolgarG.The nasal resistance of newborn infants. J Pediatr1965;67:557–567.
8.
GoldmanSL, BradyJP, DumpitFM. Increased work of breathing associated with nasal prongs. Pediatrics1979;64:160–164.
