Biomedical subjects
Publications and source records attributed to V K Stepanov.
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.
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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The paper discusses the emergence of spontaneous hypocapnia in real aircraft flights. The flying personnel were taken under study. The hypocapnic state was diagnosed on the basis of the CO2 concentration in the alveolar air measured by a special device. In flight the CO2 concentration in the alveolar air decreased insignificantly (by 5 min Hg on the average). In emergency situations the external respiration was activated to a greater extent. It is suggested that the alveolar Pco2 level is indicative of the emotional stress.
The treatment of 313 patients (317 eyes) with purulent injuries of the cornea was studied. The medication therapy was found to be effective in 173 patients (176 eyes), which made up 56.2%. The purulent process in the cornea was arrested after the therapeutic penetrating and lamellar keratoplasty in 62 patients (63 eyes or 20.1%). 74 patients (74 eyes or 23.7%) were cured through the loss of an organ: enucleation was made for 63 patients, evisceroenucleation--for 8 patients and evisceration--for 3 persons. Before the onset of purulent pathology, all removed eyes were blind due to different diseases and traumas. Pathomorphological examinations of 63 enucleated eyes showed, in 76.2% of cases, purulent-and-inflammatory changes only in anterior eye segment, and in 23.8% of cases they showed that the purulent process extended into the posterior segment structures of the eyeball; it is noteworthy that the signs of developing endophthalmitis were found only in 6.3% of cases. The obtained morphological data are indicative of that not all therapeutic possibilities were used to preserve the injured but unpromising (in the optic sense) eyes. We conclude that the absolute indication for removing an eye with purulent pathology of the cornea is the generalizing process, i.e. endophthalmitis or panophthalmitis.
Fourteen airworthy men, aged 19-20 yrs., participated in the experiments aimed at studying a prognostic significance of biochemical and hormonal parameters in evaluation of human tolerance to acute hypoxic hypoxia. Altitude chamber experiments were performed to study the tolerance to hypoxia by "ascending" the test subjects to an altitude of 6 to 7 km. It is found that under extreme hypoxic environments, of particular significance is an individual strategy of the adaptive responses and primarily an activity and adequacy of mobilization processes of energy resources in the preliminary and initial stages of an exposure. Of great value are the potential causes for maintaining the vascular tone. The use of a proposed discriminant function analysis for evaluating and predicting the tolerance to hypoxia is recommended.
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.
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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.
The author analyzes the results of sclera fortification carried out in 154 patients (220 eyes) with progressive myopia by the method he developed, consisting in transplantation of dry solid multilobar perforated transplant of silica-dried sclera that retained its natural configuration in the course of preservation. The method is simple, safe for the patients, since compression of vorticose veins and optic nerve is ruled out, easily tolerated, and yields a high stabilizing effect (97 percent) as evidenced by a follow-up of 1.5 do 3 years.