Forced Oscillatory Tecnique (FOT), Maximal (M) and Partial (P) Forced Expiration Curve To Evaluate Extravascular Lung Fluid Accumulation Due to Exposure to High Altitude (HA)

Increased extravascular lung fluid has been reported at HA. To define at which altitude it appears we studied 9 lowlanders (4F,5M mean age 35,2) at sea level, 3500m, 5050m (1st an 4th day) by maximal (M) and partial (P) forced expiration curve, respiratory resistance (Rrs), respiratory reactance (Xrs) at different frequencies, urinary protein (UP) (24 hrs collection in a rest day), bioelectrical body impedence. (see table below). We assume that the decrease in MEF25P and the lack of decrease in Rrs at high altitude indicate increased pulmonary extravascular fluid. It is reported that Xrs may be more sensitive than Rrs in detecting bronchial and interstitial diseases. Our data indicate that Xrs rappresents a better marker of increased extravascular lung fluid at HA and may be less sensitive than Rrs to variations in air density. We conclude that capillary permeability is already present at 3500 m (mean SpO2 <90%) and persists at higher altitude (5050m). Increased body electrical impedence at higher altitude suggests increase in extravascular fluid. MEF25P and Xrs are better markers in detecting peripheral airways compression/obstruction.