Biomedical subjects
Publications and source records attributed to M V Dvornikov.
Controlled normobaric interval hypoxytherapy and impulse low-intensity magnetic field application were proved to be the most promising methods that increase nonspecific resistance. Technical means to use those methods are specified.
The article has analyzed the main development and improvement stages of medical support of high-altitude flight safety. Test results of a full-scale model of the on-board active flight-safety system [symbol: see text]-2 have been given. There have been formulated prospective trends of further studies of the complex system development of crew-life support, widespread use of computer-aided technologies, as well as practical introduction of rehabilitating hypoxy-based trainings in order to increase in the pilot organism functional reserves.
The paper outlines the basic landmarks of the activity of the workers of the RF State Research Test Institute of Aviation and Space Medicine who have solved the problems of altitude flight safety provision, designed various sets of oxygen and altitude equipment. The main results of the investigations made by the Altitude Department of the Institute are summed up and some promising directions of its workers' activities are shown.
On the basis of theoretical and experimental researches the authors have developed a method for determining the maximum permissible stay time during cold tolerance, taking into account the physical activity of a man, thermostability of his dressing, temperature and wind characteristics. A special nomogram can be used for this matter. These methods give the possibility for the command and medical service to prognosticate the allowable stay time of personnel on the air at low temperature.
Formulae are developed, which describe the influence of changed human heat status on the certain physiological parameters (average body and skin temperatures, gradient of average temperature from chest to feet, water losses and pulse gradients). An algorithm is elaborated for calculation of integral parameter of human heat status, which is expressed in numbers. The parameter accounts for the heat exchange between body and environment, takes heat containing, thermoregulation and heat sensation levels into consideration.
In experimental conditions the authors have modelled the state of acute hypoxia in pilots with disorders of high psychic functions. In the result of these researches it was found out that the changes of peak frequency of alpha rhythm anticipated the slow delta and theta rhythms. This EEG characteristic feature could be used for the development of a device which would control these states in pilots.
The effect of altitude chamber hypoxia of different intensity and duration on epinephrine and norepinephrine excretion was investigated. The hypoxia tolerance as a function of catecholamine excretion was also examined. At altitudes 5000 and 6500-7000 m the test subjects were kept for a short time and at 3500-4500 m for 24 hours. The subjects with high hypoxia tolerance showed an increased and those with low tolerance a decreased epinephrine excretion. The epinephrine excretion did not increase with the intensity and duration of the hypoxia effect. Variations in the norepinephrine excretion were insignificant in all tests.
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Functional state of the pool of erythrocytes was evaluated in ten essentially healthy male subjects before, during and in 2 months after a series of 15 exposures to normobaric intermittent hypoxia (NIH). The erythrocyte pool dynamics, hemoglobin content, low and highly resistive fractions of erythrocytes were analyzed using a modified acidic histogram technique. It was demonstrated that the erythrocyte pool was either in the state of destruction (concurrent to the NIH exposure) or ensuing persistent improvement of the functional characteristics under study.
Effects of normobaric interval hypoxic training (NIH) on blood aggregation (BA) were studied in 22 male subjects (19 to 50 y.o.) given three types of treatment courses with hypoxic mixtures of nitrogen and 10 % oxygen (HGM10): short (5-7 sessions of six 5-min HGM10 cycles with 5-min intervals for breathing air), standard (10 sessions with the six HGM10 cycles), and extended (15 sessions with six 7-min HGM10 cycles alternating with 3-min air breathing). The standard and extended treatment courses did not lead to the positive BA dynamics and were characterized by asynchronous jumping of the rheologic and coagulolithic potentials. The standard course produced moderate synchronous dynamics of the biochemical and biophysical BA modules at fairly high and essentially equal rheologic and coagulolithic potentials and, therefore, proved to be best for normal males. NIH was recommended for treatment and prophylaxis in aviation medicine as an advanced method to facilitate accommodation to harsh occupational environments.
Blood aggregation was studied in human subjects of different age groups given normobaric hypooxytraining. The experiment was performed with participation of two groups of volunteers: experienced human subjects well-adapted to hypoxia and young non-adapted subjects. NOT protocol included 7 min of breathing hypoxic mixture (90% N2 and 10% O2) and 3 min of breathing atmospheric air at room temperature, 6 cycles every other day during one month. Blood aggregation was assessed by 26 parameters with the use of a multifunctional diagnostic system that permitted biophysical (rheologic), biochemical (coagulative) and mathematic (systemic) diagnostics. Two groups of the human subjects displayed significantly different reactions to of blood aggregation to the extreme factor (NOT). There was a marked dependence of the blood aggregation reaction to the hypoxic factor on the body protective-adaptive potential. Our data substantiate the need to develop NOT protocols for pilots of specific ages.
Variations in coronary circulation, cardiac output and heart rate were examined by dopplerography in 14 test subjects kept in an altitude chamber. It was found that during acute hypoxia the effective coronary blood flow decreased distinctly prior to general circulatory disorders. It is recommended to monitor coronary circulation during altitude exposures.
In many cases of death from oxygen deficit in an enclosure the development of a pathologic state is adequate to development of high-altitude hypoxia. This fact prompts extrapolation of high-altitude physiology data to such cases and helps calculate the onset of loss of consciousness and death. Methods of such calculations to be used in practical forensic medical expert evaluations are presented.