Using low-frequency oscillation to detect bronchodilator responsiveness in infants

• Published in: American journal of respiratory and critical care medicine Vol. 157; no. 2; pp. 574 - 579
• Main Authors: HAYDEN, M. J, PETAK, F, HANTOS, Z, HALL, G, SLY, P. D
• Format: Journal Article
• Language: English
• Published: New York, NY American Lung Association 01.02.1998
• Subjects: Administration, Inhalation; Airway Resistance - drug effects; Albuterol - pharmacology; Biological and medical sciences; Bronchi - drug effects; Bronchodilator Agents - pharmacology; Electric Impedance; Heart Rate - drug effects; High-Frequency Ventilation; Humans; Infant; Investigative techniques of respiratory function; Investigative techniques, diagnostic techniques (general aspects); Lung - drug effects; Lung - physiology; Male; Medical sciences; Respiratory Physiological Phenomena; Tropical medicine; Human; Pharmacologic test; Spirometry; Agonist; Bronchodilator; Bronchus; Exploration; Infant; β2-Adrenergic receptor; Wheezing; Bronchomotricity; Respiratory system; Low frequency; Inhalation; Forced oscillation; Measurement technique; Salbutamol
• ISSN: 1073-449X; 1535-4970
• 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.