Volume dependence of respiratory impedance in infants

F. Peták, M. J. Hayden, Z. Hantos, P. D. Sly

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Abstract

We previously studied low-frequency respiratory impedance (Zrs) data at an elevated lung volume to separate airway and tissue mechanical properties in normal infants (Am. J. Respir. Crit. Care Med. 1996; 154:161-166). The aim of the present study was to determine the volume dependence of the airway and tissue mechanics by extending Zrs measurements to lower lung volumes. Zrs spectra between 0.5 and 21 Hz were measured in supine sleeping infants (n = 8; 7 to 26 mo of age) at mean transrespiratory pressures (Ptr(mean)) of 20 10, and 0 cm H2O during periods of apnea induced by inflating the infants' lungs to a pressure of 20 cm H2O through a face mask. At each inflation pressure, a model containing airway resistance (Raw) and inertance (law) and tissue damping (G) and elastance (H) was fitted to Zrs data. At FRC, the values of Raw, law, G, and H were 20.6 ± 4.9 (SD) cm H2O · s/L, 0.03 ± 0.014 cm H2O · s2/L, 39.6 ± 10.3 cm H2O/L, and 147 ± 35 cm H2O/L, respectively. Increase of Ptr(mean) caused a monotonous decrease in Raw (42 ± 7% of the value at FRC), while law remained constant. The tissue parameters were minimal at a Ptr(mean) of 10 cm H2O (68 ± 10% and 78 ± 6% in G and H, respectively) and significantly higher at both 0 and 20 cm H2O. Although Zrs measurements can be made in most infants at lung volumes as low as FRC, an inflation pressure of 20 cm H2O provides a higher success rate and is therefore a more suitable condition for general use.

Original languageEnglish
Pages (from-to)1172-1177
Number of pages6
JournalAmerican Journal of Respiratory and Critical Care Medicine
Volume156
Issue number4 I
Publication statusPublished - 1997

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Electric Impedance
Pressure
Lung
Economic Inflation
Airway Resistance
Apnea
Masks
Mechanics

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

Cite this

Volume dependence of respiratory impedance in infants. / Peták, F.; Hayden, M. J.; Hantos, Z.; Sly, P. D.

In: American Journal of Respiratory and Critical Care Medicine, Vol. 156, No. 4 I, 1997, p. 1172-1177.

Research output: Contribution to journalArticle

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