MEASUREMENT OF RESPIRATORY IMPEDANCE IN HEALTHY CALVES USING THE IMPULSE OSCILLATION TECHNIQUE - PHYSIOLOGICAL AND METHODOLOGICAL ASPECTS

The aim of the present study was to investigate methodological and phy siological aspects of complex respiratory impedance measurements in ca lves using the impulse oscillation technique. To apply the system to a nimals, a tightly fitting face mask was used. The measuring system was modified by placing a flexible tube between the pneumotachograph and the loudspeaker. Complex respiratory impedance measurements were not s ignificantly influenced by the modification. Linear correlations were found between body weight and respiratory impedance; as body weight in creased, resistance decreased and reactance increased. The methodologi cal variability of impedance measurements using the impulse technique was found to be extremely small. Diurnal variations of respiratory imp edance were considered to be the main source of intra-individual varia bility. When comparing different animals (even when healthy and matche d for age and body weight) our results suggest that inter-individual b iological variability must be carefully considered.