Using low-frequency oscillation to detect bronchodilator responsiveness in infants

Am J Respir Crit Care Med. 1998 Feb;157(2):574-9. doi: 10.1164/ajrccm.157.2.9703089.


The potential of the low-frequency forced oscillation technique (FOT) to measure the response to inhaled salbutamol was studied in 13 infants with a history of recurrent wheeze and nine healthy infants. The input impedance of the respiratory system (Zrs) between 0.5 and 20 Hz was measured at a transrespiratory pressure of 20 cm H2O during a brief Hering-Breuer reflex-induced pause in breathing. Parameters representing the airway resistance (Raw) and inertance (law), and a constant-phase tissue damping (G) and elastance (H) were estimated from the Zrs spectra. Lung function was measured before and after the administration of 500 microg of salbutamol via a small-volume metal spacer. Six of these infants also received a placebo aerosol. A fall in Raw (13% for the entire group) occurred following treatment with salbutamol (p < 0.008) but not placebo. There was no significant difference in the response to salbutamol between the normal infants (7.65% +/- 5.49%) and those with recurrent wheeze (17.58% +/- 8.67%). On grouped data, the fall in G just failed to reach statistical significance (p = 0.05) after correcting the significance level for multiple tests. No significant change occurred in law or H. We conclude that the low-frequency FOT is a suitable methodology for studying bronchodilator responsiveness in infants.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Airway Resistance / drug effects
  • Albuterol / pharmacology*
  • Bronchi / drug effects*
  • Bronchodilator Agents / pharmacology*
  • Electric Impedance
  • Heart Rate / drug effects
  • High-Frequency Ventilation*
  • Humans
  • Infant
  • Lung / drug effects
  • Lung / physiology
  • Male
  • Respiratory Physiological Phenomena


  • Bronchodilator Agents
  • Albuterol