Forced oscillometric technique (fot) performed with two instruments during simulated ascent in hypobaric chamber

FOT is useful to measure both the airway resitance (Ros) and the reactance (Xrs) which is thought to reflect lung inertive and elastic properties. Before a high altitude research project we aimed to test the performance of two instruments and the effect of reduced barometric pressure on Ros and Xrs during a simulated ascent in the hypobaric chamber of Italian Air Force. With an impulse oscillometry instrument (Jaeger) (A) and a pseudo random noise instrument (Cosmed) (B) 6 subjects (4M,2F age 32-64 yrs) measured Ros and Xrs at sea level (SL), 3500m, 4200m and 5050m during the 20 minutes stay at each altitude. As expected Ros decreased with increasing altitude while no significant change was found in Xrs. The comparison between the 2 instruments did not show any significant difference. We conclude that oscillatory technique with both instruments can be an useful method to study lung mechanic changes at high altitude.