[The principles of oxygen standardization in artificial hyperbaric gas mixtures during the prolonged stay of aquanauts at depths down to 500 m].

In simulation of saturation dives at 3.6-5.1 MPa, physiologically optimal limits of oxygen partial pressure were determined in breathing gas mixtures.

[Conditions for the development of isobaric counterdiffusion of inert gases and the criteria of its evaluation].

Investigation of superficial counterdiffusion of nitrogen against helium has been carried out to evaluate a possibility of its progress in divers (107 tests) under pressures equivalent to 32-450 m of sea water when breathing trimix being saturated in heliox at a constant ambient pressure without changing chamber environment. Breathing gas mixture contained 248-800 kPa of nitrogen, while chamber heliox media contained some additions of nitrogen (6-108 kPa). Clinical manifestations of breathing trimix (itching and gas bubble formation) were studied in divers.