[Influence of changed gas media on acoustic parameters of human forced exhalation].

In previous study it was shown that duration of tracheal forced expiratory noises is promising to reveal negative changes of lung function after dive. The objective is a study of parameters of tracheal forced expiratory noises in changed gas media. The first experiment involved 25 volunteers (22-60 years), performed forced exhalation under normal pressure with air, oxygen-helium and oxygen-krypton mixtures. The second experiment in the chamber involved 6 volunteers (25-46 years), which performed forced exhalation with air under normal pressure (0.1 MPa), and under elevated pressure 0.263 MPa with air and oxygen-helium mixture. In the first experiment the direct linear dependence on gas density was found for forced expiratory noises common duration in the band of 200-2000 Hz and for its durations in narrow 200-Hz bands, excluding high frequency range 1400-2000 Hz. In the second experiment a significant reversed dependence of high frequency durations and spectral energies in 200-Hz bands (1600-2000 Hz) on adiabatic gas compressibility. Individual dynamics of common duration of tracheal forced expiratory noises under model dive of 16.3 m (0.263 MPa) is more then the diagnostic threshold of this parameter for lung function decrease, previously obtained for divers under normal pressure.

[The model of nighttime carbon oxide variation in atmosphere of a habitable pressurized module].

A mathematical model was found to describe variations in atmospheric carbon oxide during night sleep of chambered test subjects. The analytical expressions make possible calculation of CO concentration in artificial atmosphere. The model was constructed from the factual laboratory test data and can be used in designing of life support systems.

[Effects of short-term oxygen breathing on the human respiratory system].

Compared were effects of cryogenic and adsorptive oxygen on the respiration system in an experiment with 8 normal female volunteers. Mechanic impedance of the respiratory tract, pulmonary ventilation function, CO transport coefficient and physical performance were determined before and after 20 minutes of oxygen breathing. Breathing two types of oxygen was found to have different effects on the real part of mechanic impedance and the ventilatory function of the lung.

[Investigation of the physiological effect of heated heliox on the human external respiration parameters].

The investigation was aimed at studying and comparison of the physiological effects of heated heliox and air on the human breathing function. Tests involved eight human subjects aged 24 +/- 4 who breathed gas mixtures and air heated to 58 +/- 5 degrees C for 21 minutes. Effects were evaluated by spontaneous pneometry and forced expiration using equipment Master Screen VIASYS. Heated heliox and air equally caused phase-by-phase growth of external breathing parameters. Conduction of the trachea and main bronchial tubes appear to increase considerably due to heated heliox rather than air.

[Monitoring of endogenous carbon monoxide elimination in exhaled air of rats in hyperoxia]. / Monitoring vydeleniia éndogennoi okisi ugleroda s vydykhaemym vozdukhom u krys pri giperoksii.

The authors offer a new method for continuous monitoring of endogenic carbon monoxide elimination in expired air of rats during inhalation of different oxygen mixtures. For the real-time CO detection at a 10 ppb level and at high CO2 and H2O concentrations the adjustable diode laser spectroscopy was used. Short intense peaks of CO in exhaled air after the onset of O2 inhalation was observed. The 60 min inhalation of 100% O2, 80% O2 and 60% O2 caused 44, 37 and 27% increases of endogenic CO as compared to initial concentrations, respectively. The duration of the effect of increased CO elimination had the tendency for a decrease with reduced concentrations of O2 in the inhaled gas mixture.