Safe Passage Astronaut Care for Exploration Missions (2001) / Chapter Skim
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Pages 37-74
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From page 37... ...
Some effects are severe and long lasting, such as loss of bone mineral density. Others are minor and temporary, such as facial puffiness due to fluid shifts (Nicogossian et al., in press)
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From page 38... ...
In it, the Institute of Medicine (IOM) Committee on Creating a Vision for Space Medicine During Travel Beyond Earth Orbit examines what is known about the effects of microgravity and space travel on the human body.
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From page 39... ...
The chapter also includes a discussion of future methods for the monitoring of astronauts' health status an important aspect of detecting, understanding, and countering the untoward physiological changes that may affect astronaut well-being and mission performance.
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From page 40... ...
The overriding reason, however, is that microgravity cannot be duplicated on Earth; it can only be approximated. The terrestrial means of research on bone mineral density loss in microgravity are bed rest, immersion in water, or immobilization.
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From page 41... ...
~ / CM DEVELOPMENT RESEARCH \_ \ Peer-Reviewed / Research / it ~ Process / physiology & environmental operational & radiation \ >' / behavior health clinical medicine health I / FUNDAMENTAL BIOMEDICAL RESEARCH \ Critical Path, Surgeons, Crew, Advisors 41 -- -- -- -- -/ ~ ~ ~ \ | REQUIREMENTS | FIGURE 2-1 Countermeasure (CM) evolution.
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From page 42... ...
Serious acute consequences of bone mineral density loss (i.e., fracture and the formation of renal stones) as well as long-term morbidity may complicate long-duration space travel beyond Earth orbit.
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From page 43... ...
lost bone mineral density during space missions in Earth orbit: on average, greater than 1 percent per month for cosmonauts on the Russian Mir space station. In contrast, there was no significant loss from bones in the upper extremity (arm)
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From page 44... ...
A mission to Mars, for example, would involve a period of low or nearly zero gravity during space travel, a second period of time in gravity well lower than that on Earth while the expedition was on the surface of Mars, a third period of time again spent in low gravity during the return flight, and the ultimate return to Earth's gravity. How these sequential changes in gravity loading will influence bone mineral density loss is unknown.
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From page 45... ...
The basis for or the implications of individual variability is not known, further complicating interpretation of the limited clinical data. Long-duration space missions in Earth orbit offer the opportunity to obtain crucial data by careful clinical research.
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From page 46... ...
The technology for the accurate testing of bone mineral density is improving and is becoming increasingly miniaturized. It will probably become necessary to assess bone mineral density changes during space missions both in and beyond Earth orbit with reasonable precision for clinical research purposes.
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From page 47... ...
They may need to be tailored to an individual's response, and ongoing monitoring of effectiveness may be required during long-duration space travel beyond Earth orbit. For most of the clinical studies, astronauts must be their own controls, which again requires the ability to conduct comprehensive analyses of bone-related metabolic parameters during space travel.
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From page 48... ...
concluded that existing cycling, rowing, and treadmill exercise protocols did not maintain muscle mass or a positive nitrogen balance. A significant contributing factor to this loss of muscle protein may be inadequate nutrition during space travel.
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From page 49... ...
Fluid shifts from extravascular to intravascular spaces and toward the upper part of the body (Thornton et al., 1987; Leach et al, 19961. This provokes objective and subjective symptoms, especially in the first days of space travel.
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From page 50... ...
However, the incidence and the severity of the dysfunction in each of these categories during shortand long-duration space missions are unknown. Currently available data (SSB and NRC, 1998c, 2000)
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From page 51... ...
reported that 47 percent of unit doses of medication given during space missions were for the treatment of SMS. These usually consisted of promethazine with or without dextroamphetamine, although the frequency of drug administration and the routes of administration were not reported.
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From page 52... ...
NERVOUS SYSTEM Useful data on neurovestibular function, sleep (circadian rhythms) , eyehand coordination, fine and gross motor functions, and visual perception and reorientation have been collected in real-time, post-space travel studies
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Recent NASA Neurolab studies, however, Reemphasize the potential importance of overt neurovestibular disturbance during space travel.
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From page 54... ...
Building a coordinated clinical research program that addresses the issues of neurological safety and care for astronauts during long-ration space travel.
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From page 55... ...
Concerns remain about the possible sequelae of changes in visual acuity, vigilance, balance, and muscular function. PERIPHERAL NERVOUS SYSTEM Published reports and presentations to the committee made little mention of sensorimotor status during or upon the return from space missions, yet sensorimotor status is an important component of muscle activation.
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From page 56... ...
REPRODUCTIVE SYSTEM The committee was unable to find many data on the effects of microgravity on the reproductive system. This is understandable, given that space missions thus far have been of relatively short duration.
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From page 57... ...
Assessment of the effects of space travel on the reproductive endocrine system and on ovulatory function should be ongoing, and NASA should consider offering preflight gamete cryopreservation for men and women who may wish to reproduce after a long-duration space mission. Clinical Research Opportunity 10.
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From page 58... ...
Because of the short durations of space missions so far, coupled with the pulsatile nature of hormone secretion by the hypophyseal-pituitary-ovarian axis, the effect of space travel on ovulatory function has not been studied (Seddon et al., 1999; Strollo, 1999~. The effects on the menstrual cycle of stress and exercise during space travel also have not been studied (Seddon et al., 1999~.
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From page 59... ...
. Other than orthostatic hypotension after space shuttle missions, in which women have a greater likelihood of presyncope during postmission "stand" tests than men (Fritsch-Yelle et al., 1996)
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From page 60... ...
URINARY SYSTEM Renal stone formation secondary to bone calcium mobilization and excretion in the urine are well-identified concerns of space travel, with an expected incidence of 0 to 5 percent. The effects of microgravity on the urinary system also include changes in urodynamics (unknown incidence)
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From page 61... ...
Monitoring During Space Travel: Development of Technology Priority should be given to the development of high-resolution, highprecision, yet minimally invasive or noninvasive methods for the monitoring of important physiological parameters and for biological imaging during all periods of space travel. Technologies are evolving rapidly and will dramatically alter monitoring capabilities during space missions.
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From page 62... ...
Giving priority to h~gh-resol? vtion, h~gh-precision, yet minimally invasive or noninvasive methods for the monitoring of physiological parameters and for imaging of the human godly derring space travel.
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From page 64... ...
, and impaired healing of fractures Occurrence of serious cardiac dysrhythmias Impaired cardiovascular response to orthostatic stress Human performance failure because of sleep and circadian rhythm problems Loss of skeletal muscle mass, strength, or endurance Inability to adequately perform tasks due to motor performance problems, poor muscle endurance, and disruptions in structural and functional properties of soft and hard connective tissues of the axial skeleton Inability to sustain muscle performance levels to meet demands of performing activities of various intensities
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From page 65... ...
Postlanding alterations in various systems resulting in severe performance decrements and injuries Habitation and life support (eight risks) continued
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From page 66... ...
66 TABLE2-Z Continued SAFE PASSAGE Immunology, Muscle Bone Cardiovascular Human Behavior Infection and Alterations Loss Alterations and Performance Hematology and Atrophy Injury to connective tissue or joint cartilage, or intervertebral disc rupture with or without neurological complications Renal stone formation Diminished Human I mmuno cardiac function performance deficiency/ failure because of infections human system interface problems and ineffective habitat and equipment design, etc. Manifestation Human Carcinogenesis of previously performance caused by asymptomatic failure because of immune cardiovascular neurobehavioral system disease dysfunction changes Impaired Altered hemo cardiovascular and cardio response to dynamics from exercise stress altered blood components Altered wound healing Altered host microbial interactions Allergies and hypersensitivity reactions Propensity to develop muscle injury, connective tissue dysfunction, and bone fractures due to deficiencies in motor skill, muscle strength, and muscular fatigue Impact of deficits in skeletal muscle structure and function on other systems
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From page 67... ...
RISKS TO ASTRONAUT HEALTH DURING SPACE TRAVEL 67 sole Rations Neurovestibular Radiation Clinical I Atrophy Adaptation Effects Capability Other Density to Impaired elop cognitive and/or sole injury, physical affective performance due ue to motion sick function, ness symptoms I bone or treatments, :tures due especially during/ leficiencies after g-level Rotor skill, changes sole strength, I muscular gue tact of Vestibular Hits in contribution to fetal muscle cardioregulatory picture and dysfunction ction on er systems Possible chronic impairment of orientation or balance function dueto . · ~ microgravily or radiation Radiation effects Illness and on fertility, ambulatory health sterility and problems heredity Development and treatment of decompression illness complicated by microgravity induced Reconditioning Difficulty of rehabilitation following landing L Serious Risks
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From page 68... ...
The Critical Path Roadmap project, with its clinical research program on countermeasures, is NASA's mechanism for the development of priorities and validation of the means of mitigating the risks that humans may be expected to encounter during exploration-class missions into deep space. As a mechanism for gathering information, the Critical Path Roadmap project is an appropriate model for clinical research in space medicine, with use of the ISS as the critical platform for clinical research in space medicine and for NASA to validate countermeasures in the space travel environment as it prepares to go beyond Earth orbit (Figure 2-21.
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From page 69... ...
The varied, significant, and potentially harmful changes in physiology associated with space travel require health care interventions to protect the well-beings of the participating astronauts and the integrity of the mission. However, traditional clinical research with astronauts is difficult because of the small number of participants available for study, the inability to replicate microgravity and its effects on Earth, restrictions on the use of control groups, and limitations on the substitution of results from studies with animals.
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From page 70... ...
It is not clear, however, how well clinical research design, strategies, and so forth fit into these initiatives, as clinical research with astronauts relevant to space medicine beyond Earth orbit, particularly validation of countermeasures, can largely be conducted only during space missions. There does not appear to be a clearly visible and transparent plan of who oversees, designs, reviews, and is responsible for this clinical research.
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From page 71... ...
Recommendation NASA should develop a strategic health care research plan designed to increase the knowledge base about the risks to humans and their physiological and psychological adaptations to long-duration space travel; the pathophysiology of changes associated with environmental forces and disease processes in space; prediction, development, and validation of preventive, diagnostic, therapeutic, and rehabilitative
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From page 73... ...
It should focus on · providing an understanding of basic pathophysiological mechanisms by a systems approach; · using the International Space Station as the primary test bed for fundamental and human-based biological and behavioral research; · using more extensively analog environments that already exist and that have yet to be developed; · using the research strengths of the federal government, universities, and industry, including pharmaceutical, bioengineering, medical device, and biotechnology firms; and · developing the health care system for astronauts as a research database.
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From page 74... ...
Astronaut Charles Conrad, Jr., commander of the first manned Skylab mission, undergoing a dental examination by Medical OfficerJoseph Kerwin, M.D., in the Skylab 2 Medical Facility during Earth orbit onJune 22, 1973. In the absence of an examination chair, Conrad simply rotated his body to an upside down position to facilitate the procedure.
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