Biomedical subjects
Publications and source records attributed to A R Kotovskaya.
The purpose of this study was to test a variety of microgravity countermeasures and anti-G suit (AGS) in long-term bed-rest and to approve them during 169-days space flight.
To develop a program of on-line medical monitoring of human subjects during rotation on a short-arm centrifuge (SAC), which is viewed as a promising method of providing artificial gravity, 153 runs were performed with participation of 17 subjects exposed to +Gz at 0.8, 1.2 and 1.6 G up to 40 minutes 3 times a day over a 3-d cycle. It was found that the on-line medical monitoring program for humans exposed to SAC +Gz loads should include recording of the system blood circulation and local circulation in head and leg vessels.
To ensure safety of cosmonauts impacted by +Gx loads during insertion into orbit of a Soyuz-type space vehicle, it is critical to conduct appropriate medical selection of candidates to space flights, to give them proper complete physical and specialized centrifuge training, and to make it sure that at the moment of actual injection the cosmonaut's posture is optimal relative to the g-vector and that the body is tight fitting the custom-molded couch. No AGS is needed. For the purposes of protection of cosmonauts descending in the Soyuz vehicles, vital are countermeasures applied in the course of flight, water-salt supplements on the descent day, and the optimal posture, an anti-g suit, and a custom-molded couch with an additional body-restraint system and dampers used on the phase of reentry.
The problem of artificial gravity (AG) in long-term missions is one of the hottest, as the existing countermeasures do not fully cope with the negative consequences of weightlessness. From two variants of AG creation--rotation of space systems around of their mass center or short radius centrifuge (SAC)--the preference is given to SAC, as technically easier variant for realization. However, the rotation of a person on SAC can cause not only positive, but also negative effects. The purpose of the present study was to perform the analysis of data of researches on a problem of AG generated by a of SAC, executed in Russia during last 20 years, and to state modern views on application of SAC as a mean of AG creation in long piloted missions.
Previous investigations have shown the necessity of anti-G protection of cosmonauts on the stage of descent from orbit. Purpose of this research is to evaluate effectiveness of an elastic anti-G suits in opposing the descent accelerations in the Soyuz space vehicles.
Artificial gravity (AG) is the basic challenge for space biology and medicine. The importance of this problem is associated with the fact that duration of the space missions will become progressively longer, but the presently available countermeasures do not provide reason enough to predict the human health safety during space missions of any duration. The creation of AG could be an efficient method for removing the negative effects of microgravity. Two principle methods of generating AG, rotation of space system (SS) and building of short arm centrifuge (SAC), have been proposed. The purpose of the present work is to review the biomedical aspects of AG in the context of its use in long-term space missions.
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An important goal of space medicine is preserving high tolerance and performance of cosmonauts an ring exposure to acceleration at the final flight stage given varying mission duration. Among physiological mechanisms limiting +Gx acceleration tolerance, an important role is played by disturbances of external respiration resulting from alterations of respiratory biomechanics, pulmonary gas exchange conditions, and arterial hypoxemia. However, at present data on external respiration changes during exposure to +Gx acceleration after simulated and real microgravity of varying duration, are extremely scanty.
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Study of acceleration tolerance at the final stage of orbital flights after exposure to weightlessness is an important element of medical support of space flights. The cosmonauts tolerance to accelerations has been analyzed during 38 space missions of 8- to 326-day duration. Tolerance to acceleration during descent in all cases was estimated as satisfactory. Acceleration tolerance during the final stage of orbital flights depended on flight duration, individual tolerance and use of countermeasures.
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In the 18.5-day flight of the Soviet biosatellite Cosmos-936 (3-22, August 1977) com-parative investigations of the physiological effects of prolonged weightlessness (20 rats) and artificial gravity of 1 g (10 rats) were carried out. Throughout the flight artificial gravity was generated by means of animal rotation in two centrifuges with a radius of 320mm. Postflight examination of animals and treatment of the flight data were performed by Soviet scientists in collaboration with the specialists from Bulgaria, Czechoslovakia, the German Democratic Republic, Hungary, Poland, Rumania, France and the U.S.A. During the flight the total motor activity of the weightless rats was higher and their body temperature was lower than those of the centrifuged animals. Postflight examination of the weightless rats showed a greater percentage of errors during maze an increase in water intake and a decrease in diuresis; a fall of the resistance of peripheral red cells; an increase in the conditionally pathogenic microflora in the mouth; a decrease of oxygen consumption, carbon dioxide production and energy expenditures; a drop in the static physical endurance; a decline in the capacity to keep balance on the rail; an increase in the latent period of the lifting reflex, etc. The centrifugal animals displayed lesser or no change of the above type. These findings together with the biochemical and morphological data give evidence that during and after flight adaptive processes in the centrifuged rats developed better.
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The major role in the genesis of varying human tolerance to decelerations that follow weightlessness is evidently played by hypodynamic and hydrostatic factors. Long disuse of compensatory antigravity mechanisms in weightlessness may bring about their deconditioning and reduction of their functional capabilities, and may finally affect general tolerance of crewmembers to decelerations. Laboratory experiments demonstrated changes in the human tolerance to Gx accelerations of varying duration (from 3 to 100 days) and tested the efficacy of different countermeasures. A decrease in the human tolerance to +Gx is on the average -2.0g. It should be noted that an elongation of simulated weightlessness (from 7 to 100 days) caused no further decrease in the +Gx tolerance. Our investigations helped to assess the threshold of human tolerance to accelerations after an exposure to simulated weightlessness and to delineate the value of real risk. The tolerance limit to +Gx accelerations which followed simulated weightlessness of the above duration ranged from 9.5 to 13.0g, averaging 11.6 +/- 1.6g. The information on the tolerance of Soviet and American astronauts to decelerations shown during re-entry in real space flights give support to the laboratory results and predictions.
Artificial gravitv generated by spacecraft rotation may prove a universal countermeasure against adverse effects of weightlessness in the future. The paper summarizes the results of ground-based biomedical investigations of artificial gravity and flight experiments aboard Soviet biosatellites Cosmos-782 and Cosmos-936. It is believed that at the present stage the major goal of such investigations is to determine the minimum efficient value of artificial gravity in long-term flights which may eliminate adverse effects of prolonged weightlessness. In ground-bound studies the highest priority should be given to the development of methods on increasing human tolerance to the rotating environment.
Creation of artificial force of gravity (AFG) to counteract the negative consequences of microgravity in manned space missions of extended duration is one of the high-priority problems of space biology and medicine. However, there are a number of especial effects of AFG (namely, structural changes in muscles and bones, and some other system) which need implantation of electrodes and sensors and are possible only with animals. That is why it is of particular interest to make studies with monkeys whose reactions to changed gravity bear much resemblance with human. The purpose of the investigation was development of a protocol of periodic gravity loads as a counter-measure against the hypokinetic syndrome in Macaca mulatta. Two series of experiments were performed. In the series, animals were split into two groups of 6 species each who were motor restrained with the head end tilted downward at 5 degrees (HDT) for 28 days. Monkeys of group-2 were periodically subjected to centrifugation (HDT+G). During the first series of experiments rotation was conducted in the +Gz direction at g-loads from 1.2 to 1.6 units for 30-40 minutes 4-5 times a week. In the second series, g-load was equal to 1.2 units and the animals were rotated 30 min. 2-3 time a week. The criterion of Y-training protocol efficacy was a test +Gz run at 3 units for 30 s. during which functioning of the cardiovascular systems and its controls was evaluated. The test run was performed prior to and after HDT. Following HDT the animals of group HDT+G were more resistant to the test than their counterparts who had not been trained on the centrifuge. Data of the investigation imply that following HDT and HDT+G alike reduced the amount of total bodily fluids (by approximately 5%), the intracellular component (approximately 4%), and plasma volume (by 6-7%). Yet, there are radical differences between the groups in the levels of reduction in extracellular fluids (by 11% and 6.5%, respectively, P<0.05) and the interstitial component (by 11.5% and 6.5, respectively, P<0.05). Prophylactic centrifugation during HDT was also positive to the muscular blood flow in lower extremities.
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