PT  - JOURNAL ARTICLE
AU  - G L Hall
AU  - Z Hantos
AU  - J H Wildhaber
AU  - P D Sly
TI  - Contribution of nasal pathways to low frequency respiratory impedance in infants
AID  - 10.1136/thorax.57.5.396
DP  - 2002 May 01
TA  - Thorax
PG  - 396--399
VI  - 57
IP  - 5
4099  - http://thorax.bmj.com/content/57/5/396.short
4100  - http://thorax.bmj.com/content/57/5/396.full
SO  - Thorax2002 May 01; 57
AB  - Background: In infants the impedance of the nasal pathways (Zn) is a significant proportion of the total respiratory impedance (Zrs). Methods: In 11 infants Zrs was partitioned into Zn and lower respiratory system impedance (Zlrs) using a nasal catheter. A low frequency oscillatory signal (0.5–20 Hz) was applied during a pause in breathing to obtain the impedance spectra. A model of the respiratory system containing an airway and tissue compartment was then fitted to Zrs and Zlrs. The airway compartment consisted of a frequency independent resistance (R) and inertance (I), while the tissue compartment was described by coefficients of tissue damping (G) and elastance (H). Results: Zrs could be reliably partitioned into Zn and Zlrs. The nasal pathway acted as a purely resistive-inertive impedance and contributed approximately half of the airway resistance (mean (SE) 44.6 (4.9)%) and most of the respiratory system inertance (71.7 (3.5)%). Conclusion: In studies investigating changes in airway resistance in nasally breathing infants, the separation of nasal and lower respiratory system mechanics will increase the sensitivity of the tests.