Monofrequency forced oscillation technique for the investigation of pulmonary function in calves: in vitro and in vivo studies.

Parameters derived from the non-invasive and simple monofrequency forced oscillation technique were compared with classical parameters of ventilatory mechanics in order to assess its usefulness for the investigation of pulmonary function in calves. To facilitate this comparison, theoretical derivations were coupled with in vitro measurements, using an artificial lung model, and with in vivo studies. These studies compared the oscillatory resistance parameters (Ros and Re) and the respiratory system compliance (Crs) against the classical pulmonary resistance (RL) and the dynamic compliance (Cdyn), respectively. Ros and Re were highly correlated (r > or = 0.87) with RL and the comparison between Crs and Cdyn gave a similarly high correlation (r > or = 0.88). Given its simplicity, its correspondence with classical parameters and its rapidity and reproducibility, monofrequency forced oscillation technique seems well suited for the investigation of pulmonary function under field conditions.