MEDICAL PROBLEMS OF ~ANNED SPACE FLIGHTS ONBOARD ORBITAL STATIONS

O.G.Ga~en~o, A.D.Egorov, K.K.Zoseliani, V.I.Maka~ov, I. G. Popo~, E.B. Shul~hen~o

I n s t i t u t e o f B iomed ica l l ~ o b l e m s , Moscow U S S R

Abs t r ac~

Medica l a s p e c t s of crew s a f e t y and l i f e s u p p o r t as w e l l as b i o m e d i c a l i n - v e s t i g a t i o n s form pa~t and p a r c e l o f t h e p r e p a r a t i o n and conduct o f manned space p rograms . The l i s t of b i o m e d i c a l p roblems r e l a t e d t o t h e s e programs i s v e r y l o n g . The p r e s e n t pape r c o n c e n t r a t e s on some o f them.

P h y s i o l o g i c a l .and ~ T g i e n i c AsPec t s

At t he p r e s e n t t ime crewmembers l i v e and work cnboard space v e h i c l e s f o r t ime p e r i o d s t h a t i n c r e a s e from flight to flight an~_ perform tasks of g~eat diversity and complexity! this makes it necessary to provide a com- fortable environment that will help them to maintain a hig~ work capacity throughout the flight ~Nefyodov, Zalo- guev, 1981). Du~in~ a long-term mis- sion the space vehicle is not only a worEing place but also a residence w i t h v e r y s p e c i f i c f e a t u r e s °

Atmosphere . The b a s i c r e q u ~ e m e n t f o r a space c a b i n a tmosphere i s t h a t i t i s t o be b i o l o g i c a l l y e q u i v a l e n t t o a normal E a r t h a tmosphe re . The So- v i e t o r b i t a l s t a t i o n s a~e p r o ~ i d e d with an a~tificial gas atmosphere, its barometric pressure and gas compo- sition being close to those on the Earth. This seems to be most adequate for man who has adapted to the Earth atmosphere in the course of evolutio~ However, the use of this atmosphere may cause problems associated with a lower pressure in the space suit end impending decompression sickness. At present investigations a~e being c a . - tied out to explore gab mixtures that a~e blologically equivalent to the Esxth atmosphere and consist of pu~e oxygen or oxygen mixed with an inert gas •

Further investlgations of the spa- ce cabin atmosphere should be aimed at the selection of optimal ratios of its main parameters, investlgation of decompression slowness and methods of its prevention as applied to the dif- ferent gas m i x t u r e s as t h e s t u d y o f an a tmosphere t h a t can be m o d i f i e d i n view of t h e cosmonau t s ' h e a l t h c o n d i - t i o n and r e q u i r e m e n t s u s i n g p ~ T s i c a l f a c t o r s ( a e r o i o n s , u l t r a v i o l e t r a d i a - t i o n , e t c . ) . With r e s p e c t t o p r o l o n g - ed f l i g h t s t he g e n e r a t i o n of a b i o t i c envi ronment t h a t , i n a d d i t i o n t o phy- s i c a l and chemica l components , i n c o r - p o r a t e s components o f b i o l o g i c a l o r i -

~ i n should be thoroughly7 e x p l o r e d Bu~nazyan, Gazanko, 1983)o

T o ~ c 9ontaminant~ o~ t~9 ~tmosDhe- ~_~. The s o u r c e Of gaseous c o n t a m i n a n t s • s p r o d u c t s of human metabo l i sm and o u t g a s s i n g o f c o n s t r u c t i o n and d e c o r a - t i v e po lymers used i n t h e i n t e r i o r . The r a t e w i t h which v o l a t i l e s u b s t a n - ce a~e r e l e a s e d from t h e po lymers l a r - g e l y depends on t h e e n v i r o n m e n t a l p a - r a m e t e r s and o p e r a t i n g c o n d i t i o n s . This makes i t n e c e s s a r y t o de ve l op h i g h l y e f f e c t i v e sys t ems f o r a i~ p u r i - f i c a t i o n from v a r i o u s gaseous admix~u- t e e °

A e r o s o l s . The s o u r c e o f a e r o s o l s , i . e . d i s p e r s e sys tems w i t h a gaseous medium and a s o l i d or a l i q u i d d i s p e r - se p h a s e , can be man p e r s e , v a r i o u s materials of the interior eumfaces (where ai~ condensate is accumulated) and life support systems. Aerosol a~- t i c l e e , when t h e y r e s i d e on the eye and a i rway mueoea, may produce mecha- n i c a l i r r i t a t i o n ° A e r o s o l p a r t i c l e s , when t h e y a c t as a d s o r b e n t s or conden- s a t i o n c e n t e r s o f t o x i c gaseous admix- t u ~ e s , may f a c i l i t a t e t h e l ~ • penet~at i- on into lower airways ~normally, aero- sols remain in the upper airways due to their high water eolubillty). Aero- sol particles tend to g~ow in number and mean d i a m e t e r which a g g r a v a t e s t h e s i t u a t i o n i n a c l o s e d manned e~vLTon- merit. A e r o s o l p a r t i c l e s may harbor v a - r i o u s , i n c l u d i n g p a t h o g e n i c , m i c r o o r - ganisms which c o n s t i t u t e b a c t e r i a l a e r o s o l s . In t he absence of g ~ a v i t y , a e r o s o l s a g g r e g a t e and form l a r g e p a r - t i c l e s , thus increasing the infectious effect of potential pathogenic agents. The problem of aerosols can be resolv- ed with the aid of different approach- ee~ use o£ materials yielding a small amount of dust, use of effective me- thods to eliminate human metabolites, use of bacterial filters and regula~ disinfection of the interior surfaces°

The purpose of ~Tgienic investiga- tions of the effect of noise and vi- bration on the human body in a pro-

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longed space f l i g h t should be c l a r i - f i c a t i o n o f maximal ly a l l o w a b l e and p ~ y s i o l o g i c a l l y n e u t r a l l e v e l s of n o i s e and v i b r a t i o n as w e l l as i d e n t i - f i c a t i o n o f p ~ y s i o l o g i c a l r e a c t i o n s o f man t o a combined e f f e c t of n o i s e , v i b r a t i o n and o t h e r f a c t o r s t h a t t a k e p l a c e i n a space c a b i n .

Life-4u~po~t systems. Analysis of e x i s t ing and a d v a n c e d l i f e - s u p p o r t sys tems shows t h a t , as most a u t h o r s c l a i m , e c o l o g i c a l c o n t r o l l e d c l o s e d sys tem seems t o be t h e b e s t . Ma~y l a - b o r a t o r i e s i n d i f f e r e n t c o u n t r i e s a r e i n v o l v e d in the development of a g r e - en -house , an imal c a r e module , e t c . t h a t can f i n d a p p l i c a t i o n onboa~d a space v e h i c l e . F u t u r e space f l i g h t s w i l l be per formed us ing v a r i o u s modu- l e s t h a t may house components o f an e c o l o g i c a l l y c l o s e d sys tem t o be used i n s p e c i f i c i n v e s t i g a t i o n s . This w i l l he lp us t o ex tend ou~ knowledge about p rope r c u l t i v a t i o n of b i o l o g i c a l ob- j e c t s in m i o r o g r a v i t y .

Clinical ,and ~hyslolo~ical Problems

Renderln~ of m~di~a ~ ai d. As the flight duration increases-the probabl- lity of various pathologies in crew- members ~ows. This makes it very im- portant to develop adequate means and methods foz t h e i ~ p r e v e n t i o n and t r e a t m e n t . In t h i s c o n t e x t , i t i s n e c e s s a r y t o i n v e s t i g a t e t h e p r o b a b i - l i t y of emergence of v a r i o u s d i s e a s e s as a f u n c t i o n o f f l i 6 h t d u r a t i o n , t o examine i n g r e a t e r d e t a i l main cause s of t he d i s e a s e s i n t h e s e c o n d i t i o n s , and t o i d e n t i f y t h e scope and p r o c e d u - r e s o f t h e r a p e u t i c m a n i p u l a t i o n s i n space flight.

The basis principles that determi- ne medical aid in space flight are~ assessment of the probability of vari- ous p a t h o l o g i e s , c o n d u c t , if n e c e s s a - r y of p r o p h y l a c t i c and t h e r a p e u t i c me- a s u r e s ; u n i v e r s a l i t y of i n s t r u m e n t s and m a t e r i a l s t o be a p p l i c a b l e in v a - r i o u s s i t u a t i o n s ; s e l e c t i o n o f h i g h l y a c t i v e d rugs w i t h a wide r a n g e of ac - t i o n and a d e q u a t e e f f e c t when the t e a reactivity of the body is modified; individual tolerance to different d r u g s .

l ~ o D h y l a c t i c a ~ e n t ~ . No m a t t e r how paradoxical it ma~ look, countermeasu- res used a t t he p r e s e n t t ime p r e v e n t the development of adaptation of the human body to the effects of micro- gravityl they are used primarily t o make up for the deficiency of muscle work and t o r e p r o d u c e t h e e f f e c t s t h a t a r e produced on t h e g~ound by t h e weight of b lood and t i s s u e f l u i d (Gu- rovsky, F~.orov, 1983! Kovalenko, Ka- syan , 1983, P e s t o v , Gera thewoh l ,197~) . These countermeasures inclUde~ physi- cal methods t h a t may r e d u c e b lood r e - d i s t r i b u t i o n du~ing o r b i t a l f l i g h t and z e a d a p t a t i o n upon r e t u r n t o t h e E a r t h and a l s o may s t i m u l a t e n e u r o - r e f l e x

mechanisms t h a t r e g u l a t e b lood c i r c u - l a t i o n i n t h e e~ec t body p o s i t i o n ( l o - wer body n e g a t i v e p r e s s u r e , e l a s t i c l e o t a r d s and a n t l - G s u i t e , muscle e l e c t ~ o s t i m u l a t i o n , e t c . ) ! p h y s i c a l l o a d s t h a t may m a i n t a i n t h e c o n d i t i o n - i n E of most i m p o r t a n t p ~ y s i o l o g i c a l s y s t e m s , a c t i v a t e venous pumps and pe- r i p h e r a l muscle h e a r t s ( e x e r c i s e s , G- suits, loads upon skeletal bones); se- lected use of various drugs; nutriti- onal control (food enrichment with salts, amino acids and vitamins, con- trolled food and water consumption) and water control (water-salt supple- mentation); optimization of the envi- ronmental p a r a m e t e r s , work and r e s t c y c l e s and p s y c h o l o g i c a l s u p p o r t .

A ~ t i f l c i a l ~ a v i ~ y . I t i s r e c o ~ u i z - ed t h a t a ~ t i f i c i a l g ~ a v i t y g e n e r a t e d in a mRn~ed space vehicle may be an additional factor that may diminish the effects of micro~avit~ and con- tribute to the normal function of the human body. I t can e a s i l y be assumed t h a t a ~ t i f i c i a l g ~ a v i t y may produced d i f f e r e n t e f f e c t s on d i f f e r e n t p h y s i o - l o g i c a l systems. On the one hand, a~ti- ficlal g~avity m~7 help prevent dis- o r d e r s i n t h e o a ~ d i o v a s c u l a ~ f u n c t i o n , f l u i d - e l e c t r o l y t e m e t a b o l i s m , musculo- s k e l e t a l , e n d o c r i n e and othe~ s y s t e m s . This has been confirmed by Cosmos-936 e x p e r i m e n t s i n which r a t s were c o n t i - n u o u s l y exposed to an artificial gra- vity of I g (llyin, 1984). On the o t h e r hand, exposu re t o a r o t a t i n g sys tem may g i v e r i s e t o unfavou~ab le changes i n c e r t a i n sys tems ( s e n s o r y c o n f l i c t s , impai~ od or l e n t a t ion and l o c o m o t i o n , e t c . ) . T h e Cosmos-936 s t u d y r e v e a l e d changes t h a t were more d i s - t i n c t i n t he c e n t r i f u g e d than i n t h e w e i g h t l e s s r a t e s d e t e r i o r a t i o n of t h e f u n c t i o n of t he CI~S h i g h e r compar t - men ts , i n h i b i t i o n of p r o t e i n m e t a b o l - ism i n t he b r a i n , d e c r e a s e o f s e n s i t i - v i t y and reactivity of t h e s e m i c i r c u - l a r canals.

The mode of application of artifi- clal F~avity - whether it should be continuous o~ intermittent - still ~e- mains to be determined. In the latter case adverse effects may arise each time when exposure to artificial F~a- vity is resumed.

Ra~la~ign safety° Xn order to provi- de radiation safety it is necessary to equip a spacecraft with various pro- tection devices (shields, specific con- flguration, radiation shelters) devi- ces fo~ doslmetric monitoring and ra- diation alarm (personal and onboard d o s i m e t e r s ) , a g e n t s f o r t he p~opb~la - xis and treatment of radiatiOn disea- se; it is also important to set up an Earth-bound center that can assess and predict the radiation level along flight ozblts (Bazn asyan, Gazenko, 1983; Kovalev, 1984}.

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Psyc hop~yslo loKic a l l:~obleme

~ . The m a n - s p a c e c r a f t sys~am~ k closed-loop system in which man acts as a receiving element ( r e c e p t o r ) and, whi le r e a c t i n g t o the information perceived, controls va~i- ou~ systems on a feedback b a s i s t o b r i n g the entire s y s t e m : L u t o a stable opt imal s t a t e . C h a r a c t e r i s t i c s and p r o p e r t i e s t h a t c o n s t i t u t e the human factor represent not isolated el&he of components of the man-machine system but i t s sys temic f e a t u r e s . The p r e - sent-d~7 development and limitations of space rocketry and technology7 p~o- v i d e a tanKible compromise between p sychophys~o log i ca l p o t e n t i a l s and t e c h n i c a l s p e c i f i c i t i e s of a c o n t r o l - led system.

The man's ability to feel and per- ceive images, to distinguish useful information and t o differentiate it from accompa~ylng noise, to select appropriate additional information, t o t ake d e c i s i o n s , to p r e d i c t and p lan the n e c e s s a r y work s u r p a s s e s s i -

~ i c a n t l y the c a p a b i l i t y o f e x i s t - eng inee r i ng dev ices o f i d e n t i c a l

s i z e and we igh t . In o the r words, when compared t o machine man may more e f - f e c t i v e l y resolve problems associated with unexpected situations and recog- nition of unfamiliar images in real time. Man may readily adapt to a con- tinuously varying environment. How- e~er, the key element in a complex control system is a delayed response of man to a modified incur signal. The vulnerable point of the human compo- nent i s t h a t he can e a s i l y ge t t i r e d , l o s e his work c a p a c i t y and t h a t he bad ly needs r e s t when working long and hard. Space f l i g h t may induce changes in p h y s i o l o g i c a l systems and thus diminish man's capabilities. Thus, one of the ma~or goals is to develop means and methods for protecting crew- members a g a i n s t s t r e s s - e f f e c t s and hence to help them to per form e f f i c i - e n t l y their duties (Hartman, 1977).

Performance. Results o£ medical in- vestigations and observations carried out in short- and lone-term space flights have demonstrated that man can efficiently work in orbital flights of up to 8 months in duration. His work capacity remains adequately high at essentially every flight stage. This is confirmed by the successful performance of complex manoeuvres and doc~ing of transport vehicles and the station at the stage of acute adapta- tion, performance of extravehicular

~ ctivity at different flight stages including flight months 6-7) with moderate physiological changes as well as adequate t o l e r a n c e to p r o v o c a t i v e , e . g . e x e r c i s e , t e s t s .

In view of the marked r o l e t h a t man plays in the man-spacecraft system, it is impor tan t t o develop methods and p r e d i c t i o n parameters fo r e v a l u a t i n g

hie work c a p a c i t y ( p ~ y s i c a l , i n t e l - l e c t u a l , v i s u a l and psychomotor) as we l l as t o i n v e s t i g a t e i t s t ime-cou~- se v a ~ i a t i o n s in Space f l i g h t . In terms of i t s i n f o r m a t i o n con t en t pe r - refinance d e t e r i o r a t i o n i s as good as

• body t empera tu re l n c : e a e e (Hartman, 197~) •

To ma in ta in high performance o f man in a pro longed space f l i g h t , i t i s n e c e s s a r y t o make c o n t r o l l i n g s y s - tems compat ib le wi th his p e r c e p t i v e , motor , i n t e l l e c t u a l and anth~opomet- t i c c h a ~ a o t e ~ i s t i c s (Zinchen~o, Muni- per, 1979); to identify tasks that can be fulfilled by crewmembers and automat ic c o n t r o l systems in f l i g h t ; t o p reven t the i~ f a t i g u e and to c o u n t e r a c t monotony! to r e g u l a r l y train their professional skills; to rationally develop work-rest-sleep cycle taking into consideration diur- nal vazlations of physiological pro- cesses, f i x e d d i s t r i b u t i o n of c y c l e phases a long t he 24-hour t ime sca l e and i t s r e l a t i o n t o the normal t ime schedule on the Ear th ; proper s e l e c - t i o n of every crewmember (based on p s y c h o l o g i c a l c h a r a c t e r i s t i c s of each c a n d i d a t e and program of the upcoming f l i g h t ) t a k i n g i n t o account p s y c h o l o - g i c a l c o m p a t i b i l i t y c o i n c i d e n c e o f goals and interests of all members; conduct of certain psychoprophylactic measures (personal cabins, crew com- patibility with the control center personnel); prope~ arrangement of lelsu~e and psychological support (presentation of emotionally valuable information, psychological reconstzuc- tlon of the environment to counteract monoto~7; replenishment of deficient social contacts and motivated regula- tion of the emotional sphere).

Space missions performed by now have shown that man can adequately adapt to a prolonged space flight. This is provided by physiological and partially anatomical rearrangements in the body (Gazenko, 1984). The strategy7 of medical support is to control the health status of space travellers or, to be more precise, to control the process of adaptation in such a manner as to allow moderate h a b i t u a t i o n to w e i g h t l e s s n e s s wi thout loosing completely adaptation to nor- mal gravity.

Refer enc es

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2. Gazenko, O.G. ~an in space, roam. Biol. Aviakosm.Med., I~84, i,---~-8

3. Gu~ovsk~v, N.N., Egorov, A.D. Some problems of space medicine. Ins Physiological Investigations in

~ . ~oscow, Medlzlna,

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4. H a ~ a a n , B. P a T c h , l o g i c a l a s p e c t s 8. of ao~ospaoe medicine. Ins l~- ~ion Of Yllgh~ £ ~ c i d e n t s . Hosodw, 1977, pp. 105-147

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oecow Sl ;a te U n i v . , l~f9 9.

6. Ilyln, E°A. I-nvesti6a~ions on Cos- mos biosatellltes. KQ~m.Bio1.Avia- kosm.Med., 1984, ] . , 5 7 - 5 5

7. Kova lev , E.E. Cu~=ent s t a t e o f r a - 10. d i s t i c h p~o~eo t ion in space f l l s h ~ s , K o ~ , P ~ o ~ . A v l a k o ~ , ~ e d . , 1984, ].. 36-45

Kovalenko, E .A . , K a z a n , I . I . On t h e O r e t i c a l a s p e c t s o f p a t h . g e n e - s i s and proI~laxis of effects of weish~lesxnese. I, n8

s ee . w , s a , , PP. • ~7 Nefyodov, Yu.G. , Za losuev , S . b . Cur ren t s t a t e and p e r s p e c t i v e s o f ~Tgienlc suppor~ o f manned space fllghts. Koem.~iol.Aviakgsm.Me~., 1981, 2

P e s t . v , L .D . , Gera thewohl , Z.G. We igh~ le s snes s . Ins Gazenko, O.Go,

Space ~ i o l o e y an~ ~ c ~ . n O ~ V01.11, Book I , - l i c e , , w , Nauka , 1975, pp. 324-369

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