Biomedical subjects
Publications and source records attributed to I V Bukhtiiarov.
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.
Magnetocardiography as a new diagnostic method for cardiologic diseases in occupational medicine. The article covers possibilities of magnetocardiography as a promising diagnostic method for cardiologic diseases in occupational medicine. The studies used 7-channels magnetocardiographic complex MKG-6073-M. The authors applied standard exercise tests in 6 apparently healthy examinees.
G-loads tolerance following hypodynamia during extended flights and effectiveness of countermeasures against possible negative impacts were studied. Subjects performed 5-hr simulated flights after which they were centrifuged with a g-gradient of 0.1 u/s in the relaxed state, and with a g-gradient of 1.0 u/s at complex-profiled 2 to 9 units in anti-g suit VKK-15. Tested were three sets of countermeasures (A, B, C) combining the following methods: physical exercises, VKK-15 provided massage of the lower body, 30-s exposure to 5 g, use of the profiled stiff and cushioned seats, electrical stimulation of the back and waist, and an air-cushion. The countermeasures were applied every hour on flight. Hypodynamia during the five-hour fighter flight was shown to have a weak detrimental effect on the pilot's functional state, performance and g-tolerance which were tempered by the proposed combinations of countermeasures.
Studies of the dynamics of human respiratory system parameters during 15-s runs with +Gz loads from 6 to 9 units and rates of rise equal to 1, 2, 3 and 5 units/s showed that increase in the rate of rise produced specific shifts in the breathing cycle structure which characterize the voluntary adaptation of humans to g-loads. Results also make it evident that despite absence of difference in the respiratory reactions during +Gz runs, in the period following exposure the distinct increases in the parameters of external breathing and gas-energy exchange correlated with the rate of g-rise. This allows the conclusion that because of the reasons discussed in the paper the physiological cost of Gz-tolerance grows as the rate of g-rise gets high.
On the data of meta-analysis performed in 10 independent Russian and international studies of the cumulative effects of piloting g-loads on functioning of the vertebral column cervical segment, the conclusion has been made concerning a statistically significant linkage between the degenerative dystrophic diseases of the vertebral column and regular exposure to the +Gz loads.
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Six test subjects were subjected to NZ and Ny/Nz accelerations in centrifuge cabin having rotation radius of 6.55 m. During rotation, test subjects have determined the position of the subjective visual vertical. The performed studies have demonstrated that during exposure to NZ and Ny/NZ accelerations the image of subjective vertical the direction of which with rise of lateral component approaches the direction of the vector of resultant acceleration. The expressivity of this effect decreases with an increase of the longitudinal component of acceleration. It was suggested that pulling of high lateral accelerations (up to 2-3 units of g) in the flight of advanced highly manoeuvrable aircrafts can hinder in-flight spatial orientation of a pilot due to appearing of the stable illusions of spatial position.
Of a pressing aspect of pilots' exposure to high levels of head-to-seat accelerations (+Gz) is the high risk of vertebral traumatization. In this connection, mineral saturation of the lumbar vertebral in test subjects systematically exposed to +Gz accelerations on centrifuge over two months and pilots of highly manouevrable fighters has been investigated. Results of the study point it out that systematic flight g-loads bring about an increase in vertebral bone mineralization. Thus, following a series of +Gz exposures of the test subjects the integrated content of mineral substances and the density of structural composition of vertebrals Z2-Z4 showed the average rises by 4.6% and 4.15%, respectively; however, the same parameters in the pilots were higher than in the control group by 8.8% and 10.6%, respectively. The paper discusses possible mechanisms underlying these phenomena.
Human respiration parameters were studied in subjects exposed to +Gz (6.0; 7.0, 8.0 and 9.0 g with a 15-s plateau and a g-gradient of 1.0 and 5.0 g/s) with the use of anti-g measures, i.e. a barber chair inclined at 30 or 45 degrees, anti-g suit VKK-15 with a pressure controller, and a positive oxygen pressure. The gas-exchange parameters were found to be indicative of the effectiveness of an anti-g protector. When used together, these protective methods (VKK-15 munitions, an oxygen respirator for positive-pressure breathing, and chair back inclination to 45 degrees) improved g-tolerance significantly.
Spatial orientation of six normal subjects (19-28 y/o males) was investigated on a centrifuge with a radius of 6.55 m by the method of subjective haptic vertical during head movements on the pattern of working head movements of pilots impacted by +Gz loads. The investigation showed that the trend and intensity of G-excess illusion could be related to the occurrence of tangential components of the gyroscopic moment +Gz vector in the utricle otolith plane.
Tolerance of +Gz (head-pelvis) centrifugation of pilots was evaluated following simulation of a long flight on single-seat fighter. The experiment involved 5 test-subjects who were exposed to +Gz before and after simulated 8-hr flight with a growth gradient of 0.1 u/s without anti-g suits and muscles relaxed; in addition, limiting tolerance of intricate profile +Gz loads of 2.0 to 9.0 units with a growth gradient of 1.0 u/s of test-subjects in anti-g suits (AGS) with a change-over pressure valve in the peak mode using muscle straining and breathing maneuvers. To counteract the negative effects of extended flight, various seat configurations: with a back inclination at 30 degrees to the +Gz vector and changeable geometry with a back inclination at 55 degrees to the vector. The other counter-measures applied were cool air shower, suit ventilation, physical exercises, lower body massage with AGS, electrostimulation of the back and lumber region, profiling of the supporting and soft parts of the seat, and 30-s exposure to +5 Gz. Hemodynamic and respiration parameters as well as body temperature were measured in the course of 8 hrs of flight and during and shortly after centrifugation. According to the results of the investigation, seat inclination at 55 degrees to the +Gz vector and tested system of countermeasures prevent degradation of tolerance of large (9 u.) loads following 8-hr flight simulation with the use of the modern anti-g gear,
Subject of the investigation was dynamics of gas-exchange parameters during exposure to lateral and laterolongitudinal g-loads (Gy, Gz, Gz/Gy) in a coach inclined at 300 from the horizontal with a rigid restraint system. Gy values varied between 0.5 and 5.0 units, Gz - between 3.0 and 9.9 units and Gz/Gy - between 2.6/1.8 and 5.0/3.0 units. In all instances, growth gradient of the radial loads was 1.0 u/s, and a period of exposure was up to 30 s. Comparison of the Gz vs. Gy tolerance revealed as a substantial increase of the physiological "cost", so a more visible disbalance of the diffusion/perfusion ratio of the lung. This is consistent with the gas-exchange data according to which lateral g-loads are a stronger stress-factor and more challenging for pilots than the longitudinal g-loads.
Functional hemodynamic overloading of the right atrium can be caused by some of the dynamic factors in aviation and space flight. Our purpose was to disclose markers of the right atrium functional overloading in 6 normal males during the Stange test and Valsalva maneuver. Computerized magnetocardiography was fulfilled before (resting subjects), during and after (resting subjects) the breathing tests. Testing on a background of the flight dynamic factors resulted in a trend toward a more superficial Z-coordinate of the myocardium signal along the whole or a greater part of the atrial complex as compared with baseline measurements at rest. A supposition has been made that this Z coordinate alteration can be a marker of functional hemodynamic overloading of the right atrium associated with the breathing tests.
In 8 healthy men exposed within a year to systematic +Gz accelerations with cycles of 2-month work on centrifuge followed by a month rest the functional state of the red blood cells was studied repeatedly and once in 26 fighter pilots. The blood was tested for such indices as hemoglobin, reticulocyte and erythrocyte counts; the functional state of erythrocyte pool was tested using a modified method of acidic erythrograms enabling one to record kinetic parameters of hemolysis: maximum rate of hemolysis and time of its development. Intensity of loads in the cycles of centrifuging was estimated from the Barton index. It is indicated that one of the effects of systematic exposure to +Gz accelerations is an accelerated destruction of the cells with reduced resistivity a function of exposure intensity. The destructive processes induced by accelerations trigger for a short time the mechanism of compensatory activation of the red blood system. Analysis of diagrams of percentage distribution of the parameters of the erythrocyte function after centrifuge runs of various intensity, and in the pilots revealed a significant compensatory activation of the red blood system only in 25% of pilots. The criterion validity of the indices tested for the system of individual control of the adaptive processes strain in the body is discussed.