Radiofrequency impedance monitoring of the biological tissues under local heating by optical radiation.

Development of methods for simultaneous control of state of biological tissues during optical treatment is the important tasks in laser surgery. We introduce a novel approach for the monitoring of the state of biological tissues in the process of its local heating by optical radiation. It is based on measurements of the electrical radiofrequency impedance kinetics of the sample during irradiation.

[The effect of various types of oxygenators on the pulmonary microvessels and surfactant activity].

Experiments were conducted on 28 dogs to study the changes of microvessels and their effect on the functional condition of pulmonary surfactants after 120-minute venoarterial perfusion and extrapulmonary gas exchange with the use of a foamy-film oxygenator and a "Sever" membrane oxygenator. A direct relationship between the condition of the microvessels and changes of pulmonary surfactant activity was revealed: factors (contact type oxygenators) causing an unfavourable effect on the terminal link of pulmonary circulation induced rapid (in 2-3 hours) development of disturbances in the surfactant system. These changes are less marked in membrane oxygenation.

[Control of hypoxia using apneic oxygenation with extrapulmonary membrane elimination of CO2].

The peculiarities and conditions of optimal gas exchange for arresting hypoxia during prolonged (3 hours) apnoea or bradypnoea were experimentally studied in 34 dogs, using the method of apnoea oxygenation and extrapulmonary membrane removal of CO2 on "Sever" membrane gas-exchanger. It was shown that successful arrest of severe ventilation disorders of respiration by this method depends on precise registration and skillful use of the factors influencing oxygenation and CO2 removal in membrane gas-exchanger connected with peripheral arteriovenous or venovenous shunts.

[Effect of the mode of extrapulmonary gas exchange on the function and metabolism of pulmonary surfactant].

The peculiarities of the functional state of lung surfactant as well as the character and degree of disorders in its phospholipid metabolism during venoarterial perfusion and extrapulmonary 120-min oxygenation carried out with the help of contact-type (foam-film) and membrane ("Sever") oxygenators were studied in 28 experimental dogs. It was shown that the functional state and phospholipid metabolism of lung surfactant were strongly dependent on the mode of extrapulmonary gas exchange (the type of oxygenator). Membrane oxygenation is more physiological than contact-type gas exchange.