Habitable Underwater Hyperbaric Facilities: Respiratory Balance in the Human Organism During Adapting to Saturation Nitrogen-Oxygen Hyperbaria

There were evaluated responses of the respiratory system to changes in the variables of the external environment under increased pressure. To the model of professional underwater human activity underwater served the conditions of full saturation in compressed air or nitrogen-oxygen gas mixtures. Technical devices were presented by a number of underwater laboratories, mounted at the bottom (Ikhtiander-66, 67 and 68), hyperbaric chambers, submersible drilling rigs (Bur-1 and 2), and an autonomous diving Ikhtiander-2 for a long stay in the water.

Studies of respiratory gases mass transport conditions in man showed than within the pressure range of 0.25-1.1 MPa at density of moderate hyperoxic and nitrogen-helio-oxygen environment up to 14 kg/m³ oxygen and carbon dioxide regimes of the organism come to a new functional level which provides the adaptation to the extremal conditions. It is determined that an increase of physiological dead breathing space, a decrease of the rate of the O₂ diffusion through the alveole-capillary barrier, intensification of unevenness of ventilator-perfusional relations in lungs and an increase of blood shunting in lungs are the main respiratory mechanisms which regulate mass transfer of O₂ and CO₂ in man under hyperbaria. The leading hemodynamic mechanism is the retention of volume blood circulation and cardiac output. It is studied how the compression rate, high partial pressures of oxygen and nitrogen, microclimate parameters in inhabited hypebaric chambers influence changes of functional breathing system. Absence of hypoxic state is proved in man (full saturation of man with nitrogen) under normoxia in nitrogen-oxygen environment with the density 6.34 kg/m³. These are also the data about accelerated rehabilitation of divers using the method of active adaptation o high altitudes. Basic directions in physiological studies of functional breathing system under increased pressure of gas and water environment are described.