[Effect of various factors on the results of lung function tests using multifrequent impulse oscillometry in calves...

The applicability of impulse oscillometry (IOS) under clinical and field conditions was tested on 31 calves and 27 young bulls over a period from 3 to 5 months, respectively. Based on the obtained 492 test results (the average of four measurements), lung function criteria resistance and reactance, measured at frequencies of 5 to 15 Hz, showed to be diagnostically relevant. In healthy calves aged 4 to 12 weeks, resistance values lay between 0.22 to 0.36 kPa/(l/s) irrespective of frequency. Reactance values were in the range of -0.014 to 0.055 kPa/(l/s) at 5 Hz, but increased with growing frequency. Within the investigated groups no correlation could be established between factors age or body mass of the animals and resistance. Increasing age, however, led to a considerable increase in reactance. Alterations of the upper airway system were coupled with an increase in resistance values while reactance remained constant. Diagnostic evaluation of individual results relating to this category was hampered by the high interindividual test value variance of 25 to 31% between healthy animals. Diseases of the peripheral respiratory system, however, were clearly characterised by a significant decrease in reactance, as well as a negative frequency dependence of resistance. It is concluded that this method at lung function testing provides a sensitive tool for detecting and recording lung function disorders in young cattle.