Interrelationship between postocclusional oscillatory pressure transients and standard lung function in healthy and asthmatic children.
We studied the correlation between characteristics of the postocclusional oscillatory airway opening pressure transients after flow interruption and body height, the degree of pulmonary hyperinflation [measured by thoracic gas volume (TGV)], and the degree of airway obstruction [measured by airway resistance (Raw)] and maximal expiratory flow at 50% vital capacity (MEF50) in 10 healthy and 50 asthmatic children age 7-16 years. Focusing on the damped oscillatory change in pressure, the first derivative of the shutter curve was analyzed, featuring a natural frequency fO and damping factor d in the time domain, and frequency FFS and power AFS in the frequency domain. A maximal frequency was found at approximately 80 Hz without a two peak distribution as described in dogs. Multiple linear forward step analysis revealed that omega O (the undamped, natural frequency) and AFS were related to body height (P < 0.001). The damping factor d (independent of body height) was related to TGV and MEF50 (P < 0.001), and FFS to Raw (P < 0.001). The analysis of the postocclusional pressure transients after airflow interruption provides information on the resistive, elastic and inertive properties of the thoraco-pulmonary system. The measurements obtained are influenced by the end-expiratory resting level (or the degree of pulmonary hyperinflation) and the degree of airway obstruction.
Frey
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U
Department of Pediatrics, University of Berne, Inselspital, Switzerland.
Kraemer
R
R
D000293:Adolescent; D000367:Age Factors; D000403:Airway Resistance; D001249:Asthma / Q000503:physiopathology*; D001827:Body Height; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D012129:Respiratory Function Tests; D012737:Sex Factors; D013223:Statistics as Topic