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 (MEF(50)) 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 f(o) and damping factor d in the time domain, and frequency f(FS) and power A(FS) in the frequency domain. A maximal frequency was found at similar to 80 Hz without a two peak distribution as described in dogs. Multiple linear forward step analysis revealed that w(o) (the undamped, natural frequency) and A(FS) were related to body height (P < 0.001). The damping factor d (independent of body height) was related to TGV and MEF(50) (P < 0.001), and F-FS 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. Pediatr Pulmonol, 1995; 19:379-388. (C) 1995 Wiley-Liss, Inc.