Evaluation of impulse oscillometry in pigs of unknown disease status originating from the field

The aim of this study was to assess impulse oscillometry as a method to characterise lung function in 58 German hybrid pigs from 29 different herds of unknown respiratory status. The variability of repeated lung function measurements increased significantly after the sixth run and therefore the average of the first six runs was used for analysis. The presence of peripheral respiratory alterations in some pigs was indicated by the negative frequency dependence of the 95th percentile of respiratory resistance (Rrs), with highest values at 3 Hz and the sharp drop of respiratory reactance (Xrs) across the whole frequency range (3-15 Hz). Respiratory resistance and reactance were negatively correlated. Reactance area was correlated with (1) Rrs at 3, 5 and 10 Hz; (2) Xrs at 3, 5, 10 and 15 Hz; (3) the frequency dependence of resistance compared between 3 and 5 Hz (R3-R5), 5 and 10 Hz (R5-R10), and 5 and 15 Hz (R5-R15); and (4) tidal volume. High repeatability and low intra-individual variability of impulse oscillometry indicate that this method is a promising tool for advanced characterisation of the pulmonary system of pigs and has potential for use for herd health monitoring.