The Russian experience in medical care and health maintenance of the International Space Station crews

The main purpose of the medical support system aboard International Space Station (ISS) is crew health maintenance and high level of work capability assurance prior to during and after in space flights. In the present communication the Russian point of view dealing with the problems and achievements in this branch is presented. An overview on medical operations during flight and after finalization of the space missions based on Russian data of crew health and environment state monitoring, as well as data on the inflight countermeasures (prophylaxis) jointly with data on operational problems that are specific to ISS is presented. The report summarizes results of the medical examination of Russian members of the ISS and taxi crews during and after visits to the ISS.     

Countermeasure of the negative effects of weightlessness on physical systems in long-term space flights

The system of countermcasure of microgravity effects has been developed in Russia that allowed to perform safely long-term space flights. This system that includes different means and methods such as special regimens of physical exercises, axial loading (“Pingiun”) and antigravity suits, low body negative pressure device (LBNP, “Chibis”) and “cuffs” and others has been used with certain variations at certain stages of flight in 27 successfully accomplished space flights that lasted from 60 to 439 days. The pre-, in- and postflight studies performed in 57 crew members of these flights have shown that the system of countermeasure is effective in preventing or diminishing to a great extent almost all the negative effects of weightlessness in flights of a year and more duration and that the intensity and duration of changes recorded in different body systems after flights do not correlate significantly to flight durations, correlating strongly to the volume and intensity of physical exercises used during flight and especially during concluding stage of it.     

The space life sciences strategy for the 21st century

In the past, space life sciences has focused on gaining an understanding of physiological tolerance to spaceflight, but, for the last 10 years, the focus has evolved to include issues relevant to extended duration missions. In the 21st century, NASA's long-term strategy for the exploration of the solar system will combine the assurance of human health and performance for long periods in space with investigations aimed at searching for traces of life on other planets and acquiring fundamental scientific knowledge of life processes. Implementation of this strategy will involve a variety of disciplines including radiation health, life support, human factors, space physiology and countermeasures, medical care, environmental health, and exobiology. It will use both ground-based and flight research opportunities such as those found in current on-going programs, on Spacelab and unmanned biosatellite flights, and during Space Station Freedom missions.     

Russian system of countermeasures on board of the International Space Station (ISS): the first results

The system of countermeasures used by Russian cosmonauts in space flights on board of International Space Station (ISS) was based on the developed and tested in flights on board of Russian space stations. It included as primary components: physical methods aimed to maintain the distribution of fluids at levels close to those experienced on Earth; physical exercises and loading suits aimed to load the musculoskeletal and the cardiovascular systems; measures that prevent the loss of fluids, mainly, water-salt additives which aid to maintain orthostatic tolerance and endurance to gravitational overloads during the return to Earth; well-balanced diet and medications directed to correct possible negative reactions of the body to weightlessness. Fulfillment of countermeasure's protocols inflight was thoroughly controlled. Efficacy of countermeasures used were assessed both in- and postflight. The results of studies showed that degrees of alterations recorded in different physiological systems after ISS space flights in Russian cosmonauts were significantly higher than those recorded after flights on the Russian space stations. This phenomenon was caused by the failure of the ISS crews to execute fully the prescribed countermeasures' protocols which was as a rule excused by technical imperfectness of exercise facilities, treadmill TVIS particularly.     

Effects of space flights on human allergic status (IgE-mediated sensitivity)

Suppression of the immune system after space flights of different duration has been reported earlier by Konstantinova [Immune system in extreme conditions, Space immunology. B. 59. M. Science 1988. 289p. (in Russian) [4]; Immunoresistance of man in space flight, Acta Astronautica 23 (1991) 123–127 [5]]. Changes in T- and B-mediated activities of the immune system were demonstrated during and after space flight. However, the influence of the space flight conditions on the allergic status of cosmonauts and astronauts is still unclear. The goal of this investigation was to analyze total blood IgE levels, specific IgE-antibodies and interleukin-4 in blood of Russian crew members before and after space flights to the International Space Station (ISS) and during a long-term isolation study. For this purpose, we used the ELISA assays as well as other special kits. It was noticed that four out of nine cosmonauts had high total serum IgE (more than normal clinical values of 120 IU/ml). At the same time, there were no statistically significant changes in serum IgE levels before and after long-term space flights (128–195 days). A similar situation was observed regarding preflight IgE levels of cosmonauts who performed short-term flights (7–11 days). However, seven out of 11 cosmonauts had increased IgE level in blood post short flights as compared with pre-flight values. We also measured specific IgE-antibodies, because their high concentration may cause the increased production of total IgE indicating sensitization of cosmonauts. This becomes more important when humans spend a longer time in the closed environment of a space vehicle. Also our ground-based investigations showed that a stay in such conditions does not enhance sensitization to allergens (total number of tested allergens 27) including food, inhalants and cross-reactive proteins. Serum interleukin-4 level measured after short- and long-term space flights was identical. A linear correlation between levels of immunoglobulin E and interleukin-4 also was not significant. Despite the fact that our investigations did not establish any influence of space flight on sensitization and development of immediate-type allergic reactions, they demonstrated the necessity to control the allergic status of cosmonauts very carefully both before and after space flights. At the same time, it is necessary to pay special attention to outcomes of atopic individuals with high pre-flight level of total blood IgE.     

Sleep in space

Manned space flights have shown it is possible to sleep in microgravity. However, some sleep disturbances have been reported which influence performance of the crew and safety of space flight. This paper reviews the main studies of in-flight sleep in animal and man. Most disturbances are related to phase lags due to operational requirements. Factors which can disturb in-flight sleep are analysed: environmental factors. Some of them are secondary to space flight ergonomics. Conversely, effects of microgravity on light-dark alternance are less known and lead to interesting problems of fundamental research, psychological factors, especially during long duration flights.     

The human cardiovascular system during space flight

Purpose of the work is to analyze and to summarize the data of investigations into human hemodynamics performed over 20 years aboard orbital stations Salyut-7 and Mir with participation of 26 cosmonauts on space flights (SF) from 8 to 438 days in duration. The ultrasonic techniques and occlusive plethysmography demonstrated dynamics of changes in the cardiovascular system during SF of various durations. The parameters of general hemodynamics, the pumping function of the heart and arterial circulation in the brain remained stable in all the space flights; however, there were alterations in peripheral circulation associated with blood redistribution and hypovolemie in microgravity. The anti-gravity distribution of the vascular tone decayed gradually as unneeded. The most considerable changes were observed in leg vessels, equally in arteries (decrease in resistance) and veins (increase in maximum capacity). The lower body negative pressure test (LBNP) revealed deterioration of the gravity-dependent reactions that changed for the worse as SF duration extended. The cardiovascular deconditioning showed itself as loss of descent acceleration tolerance and orthostatic instability in the postflight period.     

Central and regional hemodynamics in prolonged space flights.

This paper presents the results of measuring central and regional (head, forearm, calf) hemodynamics at rest and during provocative tests by the method of tetrapolar rheography in the course of Salyut-6-Soyuz and Salyut-7-Soyuz missions. The measurements were carried out during short-term (19 man-flights of 7 days in duration) and long-term (21 man-flights of 65-237 days in duration) manned missions. At rest, stroke volume (SV) and cardiac output (CO) as well as heart rate (HR) decreased insignificantly (in short-term flights) or remained essentially unchanged (in long-term flights). In prolonged flights CO increased significantly in response to exercise tests due to an increase in HR and the lack of changes in SV. After exercise tests SV and CO decreased as compared to the preflight level. During lower body negative pressure (LBNP) tests HR and CO were slightly higher than preflight. Changes in regional hemodynamics included a distinct decrease of pulse blood filling (PBF) of the calf, a reduction of the tone of large vessels of the calf and small vessels of the forearm. Head examination (in the region of the internal carotid artery) showed a decrease of PBF of the left hemisphere (during flight months 2-8) and a distinct decline of the tone of small vessels, mainly, in the right hemisphere. During LBNP tests the tone of pre- and postcapillary vessels of the brain returned to normal while PBF of the right and left hemisphere vessels declined. It has been shown that regional circulation variations depend on the area examined and are induced by a rearrangement of total hemodynamics of the human body in microgravity. This paper reviews the data concerning changes in central and regional circulation of men in space flights of different duration.     

Using the PROGRESS transport spacecraft in structure of the International Space Station for realization of scientific experiments under microgravity conditions

The problem is considered of using the PROGRESS transport spacecraft, which will deliver the payload on the ISS, as a free flying platform for realization of space experiments. For maintenance of the ISS 5-6 PROGRESS flights per year are planned. Usually after delivery of the payload the PROGRESS undocks from the ISS and burns down in the Earth atmosphere. However, the operating conditions of its onboard systems allow to prolong operation and to make free flight near to the station and repeatedly to be docked to it. It is offered to use this possibility for performing experiments on Material Science.     

Structured methods for identifying and correcting potential human errors in space operations

Human performance plays a significant role in the development and operation of any complex system, and human errors are significant contributors to degraded performance, incidents, and accidents for technologies as diverse as medical systems, commercial aircraft, offshore oil platforms, nuclear power plants, and space systems. To date, serious accidents attributed to human error have fortunately been rare in space operations. However, as flight rates go up and the duration of space missions increases, the accident rate could increase unless proactive action is taken to identity and correct potential human errors in space operations. The Idaho National Engineering and Environmental Laboratory (INEEL) has developed and applied structured methods of human error analysis to identify potential human errors, assess their effects on system performance, and develop strategies to prevent the errors or mitigate their consequences. These methods are being applied in NASA-sponsored programs to the domain of commercial aviation, focusing on airplane maintenance and air traffic management. The application of human error analysis to space operations could contribute to minimize the risks associated with human error in the design and operation of future space systems.     

Bone effects of space flight: analysis by quantum concept of bone remodelling.

During the manned Skylab flights mineral losses from the calcaneum and changes in external calcium balance were in the ranges found for healthy subjects at bedrest. Calcium balance reached a nadir of -200 mg/day by two months with no change thereafter; the negative balance was due to increased urinary excretion with no change in net absorption. The total calcium loss averaged 18 g in the longest flight of 84 days; the densitiometric data suggested that about two-thirds of this came from trabecular bone and about one-third from cortical bone. These data could represent reversible bone loss due to increased birth rate of normal osteoclasts and osteoblasts and consequent increase in bone turnover and in reversible mineral deficit, or irreversible bone loss due to overactive osteoclasts and/or underactive osteoblasts. If the former explanation is correct, significant bone loss is unlikely whatever the duration of future flights, except in older persons already losing bone; if the latter explanation is correct, space flights longer than six months may lead to a significant increase in fracture risk in later life. Neither terrestrial immobilization nor unwilling animals in orbit are ideal models for the effects of space flight on human bone. To choose between reversible and irreversible mechanisms of bone loss, and to determine the effects of space flight on lifelong fracture risk, future astronauts and cosmonauts must undergo adequate histologic study of bone after in vivo tetracycline labeling.     

Biomedical problems of EVA support during manned space flight to Mars

Current projects of manned missions to Mars are aimed to their realization in the second-third decades of this century. The purpose of this paper is to determine and review the main biomedical problems, that require a first and foremost decision for safety support of extravehicular activity (EVA) carried out by crewmembers of the Mars expedition. To a number of such problems the authors of the paper attribute a creation of adequate EVA equipment intended, first, for assembly of interplanetary spacecraft on the Earth orbit, performance of maintenance operations and scientific researches on the external surface of spacecraft during interplanetary flight and, secondly, for work on the Mars surface. New generation of space suits with low weight, high mobility and acceptable risk of decompression sickness must be as a central component of EVA equipment. The program for preparation to a Mars expedition also has to include special investigations in order to design the means and methods for a reliable protection of crew against space radiation, to elaborate the approach to medical monitoring and primary medical care during autonomous space mission, to maintain good health condition of crewmembers during EVA under the Mars gravity (0.38 g) after super long-term flight in weightlessness.     

The effects of extreme nutritional conditions on the neurochemistry of reward and addiction.

Weight loss is a frequent problem in space flights. We now claim that it may affect performance and drug-seeking behavior by altering midbrain neurochemistry. In food-deprived rats (20-30% underweight) basal extracellular dopamine levels in the nucleus accumbens decrease to 40-50% of normal and locomotion is depressed. However, amphetamine-induced dopamine release and locomotion are higher than in controls (1825% vs. 595% after a 25 micromoles d-amphetamine intraaccumbens infusion). The lower basal and the higher stimulated dopamine levels suggest that the neurotransmitter accumulates presynaptically in the accumbens of the underweight rats due to subnormal basal release. Psychostimulants are more rewarding for underweight subjects possibly because they release significantly more dopamine from elevated presynaptic stores into the accumbens. Consequently, weight loss can lead both to depression of performance and propensity to substance abuse. These effects should be considered when providing nutritional resources for space flights so that weight loss is limited.     

Exercise response to simulated weightlessness

Two bed rest analog studies of space flight were performed; one 14 d and the other 28 d in duration. Exercise response was studied in detail during the 28 d study and following both the 14 d and 28 d studies. This paper relates the results of these studies to physiologic changes noted during and following space flight. The most consistent change noted after both bed rest and space flight is an elevated heart rate during exercise. A second consistent finding is a postflight or postbed rest reduction in cardiac stroke volume. Cardiac output changes were variable. The inability to simulate inflight activity levels and personal exercise makes a direct comparison between bed rest and the results from specific space flights difficult.     

Cognitive performance aboard the life and microgravity spacelab

The impact of microgravity and other stressors on cognitive performance need to be quantified before long duration space flights are planned or attempted since countermeasures may be required. Four astronauts completed 38 sessions of a 20-minute battery of six cognitive performance tests on a laptop computer. Twenty-four sessions were preflight, 9 sessions were in-orbit, and 5 sessions were postflight. Mathematical models of learning were fit to each subject's preflight data for each of 14 dependent variables. Assuming continued improvement, expected values were generated from the models for in-orbit comparison. Using single subject designs, two subjects showed statistically significant in-orbit effects. One subject was degraded in two tests, the other was degraded in one test and exceeded performance expectations in another. Other subjects showed no statistically significant effects on the tests. The factors causing the deterioration in the two subjects can not be determined without appropriate ground-based control groups.     

Oxygen regimen in the human peripheral tissue during space flights.

A survey of the results of the experiment "Oxygen," carried out within the scope of the INTER-KOSMOS program in members of the permanent crews and of international visiting expeditions to the Soviet orbital station Salyut-6, is given. During the 7-day space flights of the international visiting expeditions a significant decrease in pO2ic by 3.28 kPa was observed. Local oxygen utilization reduced significantly by 0.44 kPa. During hyperventilation testing after return to earth a statistically significant decrease in the peak value by 1.39 kPa was noted. In the long-term crews of the orbital station Salyut-6 the highest decrease in pO2ic of 3.8 kPa and the absolutely lowest value of 3.4 -/+ 0.5 kPa during space flight were observed. The decrease in local oxygen utilization during the flight of 0.8 kPa/min was greater than that of the visiting crews. The results indicate the importance of investigating the dynamics of the oxygen regimen for medical control of the crew members both during the space flight and during the readaptation phase after return to earth.     

Catecholamines and their enzymes in discrete brain areas of rats after space flight on biosatellites Cosmos

The activity of the catecholaminergic system was measured in the hypothalamus of rats which had experienced an 18.5-19.5-day-long stay in the state of weightlessness during space flights on board Soviet biosatellites of the type Cosmos. In the first two experiments, Cosmos 782 and 936, the concentration of norepinephrine and the activities of synthesizing enzymes tyrosine hydroxylase and dopamine-beta-hydroxylase and of the degrading enzyme monoamine oxidase were measured in the total hypothalamus. None of the given parameters was changed after space flight. In the light of the changes of these parameters recorded after exposure to acute stress on Earth, this finding indicates that long-term state of weightlessness does not represent an intensive stressogenic stimulus for the system studied. In the space experiment Cosmos 1129, the concentration of norepinephrine, epinephrine, and dopamine was studied in isolated nuclei of the hypothalamus of rats within 6-10 hr following return from space. Norepinephrine was found to be significantly reduced in the arcuate nucleus, median eminence and periventricular nucleus, epinephrine in the median eminence, periventricular and suprachiasmatic nuclei, whereas dopamine was not significantly changed after space flight. The decreased catecholamine levels found in some hypothalamic nuclei of rats which had undergone space flight indicate that no chronic intensive stressor could have acted during the flight, otherwise the catecholamine concentration would have been increased in the nuclei. The decreased levels must have been induced by the effect of a stressogenic factor acting for a short time only, and that either during the landing maneuver or immediately after landing. Thus long-term exposure of the organism to the state of weightlessness does not represent a stressogenic stimulus for the catecholaminergic system in the hypothalamus, which is one of the regulators of the activation of neuroendocrine reactions under stress.     

Identification and status of design improvements to the NASA Shuttle EMU for International Space Station application

To meet the significant increase in EVA demand to support assembly and operations of the International Space Station (ISS), NASA and industry have improved the current Shuttle Extravehicular Mobility Unit (EMU), or "space suit", configuration to meet the unique and specific requirements of an orbital-based system. The current Shuttle EMU was designed to be maintained and serviced on the ground between frequent Shuttle flights. ISS will require the EMUs to meet increased EVAs out of the Shuttle Orbiter and to remain on orbit for up to 180 days without need for regular return to Earth for scheduled maintenance or refurbishment. Ongoing Shuttle EMU improvements have increased reliability, operational life and performance while minimizing ground and on-orbit maintenance cost and expendable inventory. Modifications to both the anthropomorphic mobility elements of the Space Suit Assembly (SSA) as well as to the Primary Life Support System (PLSS) are identified and discussed. This paper also addresses the status of on-going Shuttle EMU improvements and summarizes the approach for increasing interoperability of the U.S. and Russian space suits to be utilized aboard the ISS.     

The dynamics of blood biochemical parameters in cosmonauts during long-term space flights

Most of the previously obtained data on cosmonauts' metabolic state concerned certain stages of the postflight period. In this connection, all conclusions, as to metabolism peculiarities during the space flight, were to a large extent probabilistic. The purpose of this work was study of metabolism characteristics in cosmonauts directly during long-term space flights. In the capillary blood samples taken from a finger, by "Reflotron IV" biochemical analyzer, "Boehringer Mannheim" GmbH, Germany, adapted to weightlessness environments, the activity of GOT, GPT, CK, gamma-GT, total and pancreatic amylase, as well as concentration of hemoglobin, glucose, total bilirubin, uric acid, urea, creatinine, total, HDL- and LDL cholesterol, triglycerides had been determined. HDL/LDL-cholesterol ratio also was computed. The crewmembers of 6 main missions to the "Mir" orbital station, a total of 17 cosmonauts, were examined. Biochemical tests were carried out 30-60 days before launch, and in the flights different stages between the 25-th and the 423-rd days of flights. In cosmonauts during space flight had been found tendency to increase, in compare with basal level, GOT, GPT, total amylase activity, glucose and total cholesterol concentration, and tendency to decrease of CK activity, hemoglobin, HDL-cholesterol concentration, and HDL/LDL - cholesterol ratio. Some definite trends in variations of other determined biochemical parameters had not been found. The same trends of mentioned biochemical parameters alterations observed in majority of tested cosmonauts, allows to suppose existence of connection between noted metabolic alterations with influence of space flight conditions upon cosmonaut's body. Variations of other studied blood biochemical parameters depends on, probably, pure individual causes.