[Individual prediction by the analysis of preflight ECG data of cardiac function disorders in cosmonauts during standard deorbit after long-term space flights and in the period of postflight observation].

ECG records of 25 cosmonauts--members of 30 long-term Mir and ISS missions (73- to 197-day long) in the period of 1995-2007 were analyzed. The ECG records were made during medical selection, clinical-physiological investigations (KFO) before launch, insertion and standard descent, and post-flight KFO. No negative trends were discovered in 70% (n=21) of ECG records during insertion and descent of cosmonauts who had not have significant ECG deviations before flight. In 20% of ECG records (n=6) pre-launch individual properties of cardiac rhythm, conduction and end of the ventricular complex became more pronounced in the period of descent persisting after landing. In 10% of ECG records (n=3) the predicted ECG deviations were not found This was the first time when dynamic analysis of ECG records made on the stages of selection and pre-launch training was successful in predicting of 90% (n=27 of 30) of cardiac function deviations during descent. At the start of rehabilitation from long-term missions essentially each of the cosmonauts displayed ECG deviations which were more considerable as compared with the KFO and descent records.

[Prediction of cardiac function deviations (ECG data) in the course of permanent cosmonaut's monitoring starting from selection till return to earth after short-duration space flight].

Analyzed were deviations in cardiac function in 29 cosmonauts with previous aviation and other occupations ranging of 29 to 61 y.o. who made 8- to 30-day space flights (totai number of flights = 34) between 1982 and 2006. The deviations were identified in ECG records collected during clinical selection, clinical physiological examination (CPE) before flight, insertion and deorbit in transport vehicles, and post-flight CPE. Based on the analysis, the cosmonauts were distributed into three groups. The first group (55.2% of the cosmonauts) did not exhibit noticeable shifts and unfavorable trends in ECG at any time of the period of observation. The second group (34.5%) showed some deviations during selection and pre-flight CPE that became more apparent in the period of deorbit and were still present in post-flight ECG records. The third group (10.3%) displayed health-threatening deviations in cardiac function during deorbit. These findings give start to important investigations with the purpose to define permissible medical risks and ensuing establishment and perfection of medical criteria for candidates to cosmonauts with certain health problems.

[On medical screening of civilian candidates for cosmonauts by exposure to the head-to-pelvis acceleration profiles].

The subject of analysis was the data on +3 and +5 Gz tolerance of 130 civilian non-pilot applicants for cosmonauts (men and women, aged 23 to 55) gathered over the past 30 years. Length of the centrifuge arm was 7.25 meters and the total number of primary centrifuge runs was 309. For nearly every second of the applicants (46.7%) acceleration at +5 Gz was an ordeal causing distinct vascular or coronary decompensation. Thus, 29.7% exhibited various combinations of brief visual disturbances, tachycardia, tachypnea, and systolic arterial pressure in the shoulders; in 17%, visual disturbances and/or their precursors were combined with exaggerated cardio-vascular functional parameters, arrhythmia, and serious vegetative disorders. Most of those who had failed to endure the first centrifugation were unable to improve G tolerance during next runs; indeed, they showed negative G-tolerance dynamics. G intolerance grew in significance or was exacerbated by new disorders and their combinations. These results testify against exposure of non-pilot applicants for cosmonauts to +5 G, during the primary medical screening.

[+Gx-tolerance by the Cosmonauts of ISS crews 1, 6-9 and visiting crews 1-7 aboard Soyuz vehicles].

Analysis of +Gx tolerance of 15 members of short-term ISS missions and 9 members of long-term ISS missions aboard the Soyuz vehicles showed good tolerance during insertion and satisfactory during descent provided the use of in-flight countermeasures and anti-g suit Kentaur inside the vehicle. Objective data about the tolerance of off-nominal +Gx (6.26 and 8.1 G) pointed to a more pronounced sinus tachycardia and tachypnea in a ballistic descent following long-duration weightlessness as compared with nominal. Physiological deviations were transient, functional by character. Cardiac arrhythmia was largely observed during return to Earth. Two cosmonauts were found to develop prognostically unfavorable ECG indications during off-nominal descent. Main factors in these deviations could be age (above 45) and existence of some individual specifics of cardiac rhythm regulation. These results emphasize the necessity of more careful screening of candidates older than 45 years, as weightlessness may impact their general condition and tolerance of g-loads during return to Earth.

[The effect of pharmacological hypohydration on g-tolerance]. / Vliianie farmakologicheskoi gipogidratsii na perenosimost' peregruzok.

A group of 6 subjects (25-45 y.o.) participated in the studies of the tolerance of lateral (chest-back, +Gx) and longitudinal (head-pelvis, +Gz) loads before and after pharmacological hypohydration. Moderate hypohydration (diminution of the circulating plasma volume by 14% and body mass by 2% on the average) induced by diuretics does not lead to a substantial loss in tolerance of +Gx up to 8.3 units but reduces the threshold of +Gz tolerance by 0.6 units. The scientific and applied sense of these data is that diuretics can be safely administered in the pre-launch period to prevent the negative effects associated with the beginning of space flight.

[Dynamics of tolerance of +G loads by non-flying subjects: a longitudinal study]. / Dinamika perenosimosti peregruzok +G, litsami neletnykh professii pri dlitel'nom nabliudenii.

Selected cosmonauts-investigators may be held on wait for many years. The longitudinal health study is of great significance in the context of prediction of tolerance to various flight stresses. The purpose of this work was to investigate the tolerance to +Gz-loads during extended (up to 18 years) dynamic longitudinal study of 50 male cosmonauts and candidates of non-flying occupations by the data of 363 medical observation runs on a centrifuge with the radius of 7.25 m. Analysis of these data showed that 82 % of the subjects sustained good tolerance of G-loads and only 18 % of the subjects displayed its decrement or instability. A new proof received the data concerning better +Gz-tolerance by subjects aged 31-35 and less tolerance by the subjects younger than 30 and older than 46-50 years. The longitudinal study allowed to identify 4 types of G-tolerance variation, i.e., stable, relatively stable with individual drops down to decreased, non-stable with periodic drops, and a distinct trend towards a decrease. These investigations provided new scientific data about the dynamics of separate physiological functions during exposure to +Gz-loads resultant from longitudinal study of the same group of subjects, and allowed to make an expert prediction of shifts in the G-tolerance.

[G-tolerance of female cosmonauts during descent in space flights of 8 up to 169 days in duration]. / Perenosimost' peregruzok zhenshchinami-kosmonavtami na uchastke spuska v kosmicheskikh poletakh dlitel'nost'iu ot 8 do 169 sutok.

Investigations into g-tolerance of female cosmonauts during descent in space flights of varying duration are topical for the present day, as there are little data on this issue. Tolerance of +Gz-loads during descent was analyzed based on the data about 4 female cosmonauts in 5 space flights. The space flights were conventionally divided into short- (8-16 days) and long-term (169 days). In two space flights (16 and 169-d long), tubeless anti-g suit Centaur was warn during descent. In these space flights, g-tolerance of females was quite satisfactory advocating for the possibility for women to fly to space without any constraints. When the anti-g suit was not used, female physiological systems were stressed heavier than male. The spacesuit smoothed away this difference. Our results evidence a distinct positive effect of wearing the anti-g suit by female cosmonauts during descent as it reduces stress to their physiological systems.

[Role of age in +Gz and +Gx tolerance by female candidates to astronauts]. / Vliianie vozrasta na perenosimost' peregruzok +Gz i +Gx zhenshchinami pri otbore v kosmonavty.

Analyzed was the role of age in the tolerance of +Gz (up to 5 units) and +Gx (up to 8 units) by female candidates to cosmonauts on the stage of initial centrifuge selection in the years of 1979 through to 1993. Selection was made of 26 healthy non-flying women aged 23 to 39 who were divided into 4 groups with 5-year intervals. Female tolerance of g-loads and shifts in a number of physiological parameters during centrifugation were discovered to be age-dependent. The poorest tolerance of +Gz and +Gx loads was typical of women below 25 years, the best, at the age of 31 to 40 years. It was stated that tolerance of these demanding g-loads by women, especially below 30, was generally worse compared with men. There were also some distinctions in the cardiovascular response in women and men. These results point to the significance of centrifugation in selection female candidates to cosmonauts irrespective of their age.

[Human tolerance of +Gx loads in anti-G suits during deorbiting of the "Soiuz" space vehicles]. / Perenosimost' chelovekom peregruzok napravleniia +Gx na uchastke spuska s orbity kosmicheskikh korablei tipa "Soiuz" pri ispol'zovanii protivoperegruzochnykh kostiumov.

Reported are results of the study of tolerance of the "thorax-back" g-loads (+Gx) during deorbiting of 83 total suited and unsuited cosmonauts in the period of 1997-1997. G-loads averaged 3.7 +/- 0.058 units (from 3.1 up to 5.1 units). Pneumatic gradient G-suits (PGS) Karkas and Centaur had a positive effect on the +Gx tolerance of humans following microgravity. As compared with unsuited crews returning from missions of similar duration, wearing PGS has proven to improve the general health of cosmonauts and to reduce the strain of the leg and abdominal muscles. Tight fitting of PGS abolished visual disorders due to the longitudinal component of G-loads that were registered in 6.6% of observations of unsuited cosmonauts. Sinus tachycardia was significantly weaker (P < 0.05). The authors recommend the use of the standard antiblackout Centaur suit as the efficacy of this PGS was equal to that of Karkas while its ergonomic characteristics were superior.

[Tolerance of +G2 gravitation overload in persons aged 41-58 years]. / Perenosimost' peregruzok napravleniia +G2 litsami v vozraste ot 41 goda do 58 let.

Forty-five men (non-pilots) aged 41-58 were used in 186 experimental runs to study their tolerance to +GZ acceleration. The test subjects were either healthy people or showed atherosclerotic symptoms (the number of which varied from 1-2 to 5 and more). During centrifugation the test subjects had no anti-G suits on. Healthy test subjects exhibited high tolerance to +Gz acceleration of up to 5 g in most centrifugal runs (90.3%). The test subjects with early atherosclerotic changes showed a significantly lower tolerance as compared to the matched controls. It was found that in the atherosclerotic subjects tolerance to +Gz acceleration decreased as its value increased and as the number of atherosclerotic symptoms grew. The major symptoms that limited tolerance to +Gz acceleration in all the test subjects were cardiac arrhythmias and in the atherosclerotic subjects they were also eye disorders and autonomic-vascular reactions during recovery. The data obtained show that it is important to measure individual tolerance to acceleration in people aged 41-58 years old.

[+Gz load tolerance in nonflight personnel of different ages]. / Perenosimost' peregruzok +Gz litsami neletnykh professii razlichnogo vozrasta.

Ninety-six healthy nonpilots, aged 21 to 50 years, were exposed to 228 rotations on a 7.25 m arm human centrifuge. The study demonstrated age-related changes in +Gz tolerance of 3 to 5 G (for 30 sec). The subjects at the age 31 to 40 years showed the highest tolerance while the subjects at the age 21 to 25 and 46 to 50 years the lowest tolerance. Young subjects (21-25 years old) often developed an asthenic type of the systolic pressure reaction in the ear lobe and visual disorders whereas older subjects (46-50 years old) displayed cardiac arrhythmias, lower heart rate and delayed recovery of blood pressure after exposure. It was also found that 60-80% subjects aged over 40 well tolerated acceleration of up to 5 G and therefore can be viewed as potential candidates for cosmonauts.

[Resistance to +Gz and +Gx loads of subjects in older age groups, healthy and with initial signs of atherosclerosis]. / Ustoichivost' k peregruzkam +Gz i +Gx u lits starshikh vozrastnykh grupp, zdorovykh i s nachal'nymi priznakami ateroskleroza.

Tolerance to +Gz and +Gx acceleration of healthy and atherosclerotic subjects, aged 40-49, was investigated during 256 centrifugation tests in Bulgaria and the USSR. As compared to the healthy people, the atherosclerotic subjects showed a lower tolerance: when exposed to 7 +Gz the tolerance threshold decreased from 5.93 +/- 0.57 g to 5.7 +/- 0.44 g (i. e. by 0.23 g). Visual disorders in the healthy and atherosclerotic subjects were recorded in 29 and 50%, respectively, and loss of consciousness in 9.56 and 15.15%, respectively (Bulgarian data). When exposed to 5 +Gz and 6 +Gx no subjects displayed visual disorders or loss of consciousness (Soviet data). However, lower tolerance of 5 +Gz due to cardiac arrhythmias was observed in 4.8% atherosclerotic patients and in none healthy subjects. Lower tolerance to 6 +Gx associated with cardiac arrhythmias was recorder in 23.8% atherosclerotic versus 11.8% healthy subjects (i. e. 12% more). Nevertheless, in most subjects, both healthy and atherosclerotic, acceleration tolerance was good. These findings indicate that individual assessment of acceleration tolerance is of great importance for people older than 40 years with health abnormalities.

[Prognostication of man's health status in response to gravity-induced blood shifts based on continuous noninvasive measurement of arterial blood pressure using the Pen'iaz method]. / Prognozirovanie sostoianiia cheloveka v usloviiakh gravitatsionnogo pereraspredeleniia krovi na osnove nepreryvnogo neinvazivnogo izmereniia arterial'nogo davleniia po metodu Pen'iaza.

Exposure to +Gz acceleration, orthostatic tilt tests and LBNP tests causes distinct blood shifts and deterioration of cerebral circulation. In this case syncope episodes may be prevented by continuous monitoring of circulation parameters, specifically arterial pressure (AP). Our investigations have shown that continuous AP measurement by the Penjaz noninvasive technique may help earlier prediction of the health status in response to gravity-induced blood shifts. In this situation the development of a pre-collapse state is preceded by an emergence of distinct AP waves of the second-third order accompanied by a critical drop of pulse pressure. It is concluded that continuous AP measurement in the finger according to the Penjaz noninvasive technique holds promise as a medical monitoring method in a altered gravitational field.