[Developing the methodology of examining the lower limb veins in cosmonauts for the space medicine practice].

The article centres on development of a methodology for evaluating the function of lower limb veins of cosmonauts in microgravity. The whys and wherefores of the choice of occlusive plethysmography equipment and procedure are explained. Much place is given to arguments for the requisite body and limb positioning during venous plethysmography pre launch and on return from space flight.

[Prediction of human orthostatic tolerance by changes in arterial and venous hemodynamics in the microgravity environment].

The authors intentionally present exclusively the results of their recent studies of arterial and venous hemodynamics as predictors of human orthostatic tolerance (OT) during space flight and on return to Earth. There is a sufficient demonstration of the in-flight OT predictability by arterial hemodynamic reactions to LBNP and venous hemodynamic changes in response to the lower extremities occlusion. Three levels of cerebral blood flow deficits in the course of the lower body negative pressure test (LBNP) performed in microgravity were first defined.

[The features of adaptation and disadaptation of the human cardiovascular system in the space flight conditions].

The work was aimed at analysis and generalization of the hemodynamic data collected over 20 years from 26 cosmonauts flown 8 to 438 days aboard orbital stations Salyut 7 and Mir. The paper presents the results of ultrasonic investigations of the heart, arterial and venous peripheral vessels in different parts of human body, and measurements of leg veins capacity with the use of occlusive plethysmograpy. It was shown that in the resting condition such prime hemodynamic parameters as the pumping function of the heart and blood supply of the brain, and integral parameters, i.

[Dynamics of human cardiovascular responses in different periods of long-term exposure in weightlessness].

Purpose of the work was to determine trends in the human cardiovascular function at rest and during LBNP in different periods of short- (8-25 d) and long-term (126-438 d) space flights (SF) using the data of USI and leg occlusive plethysmography. Due to blood redistribution and hypovolemia in the first week on SF, the cardiovascular system decreased the left heart filling and output without loss in myocardium contractility, weakened the renal artery resistance, and increased the maximum capacity of leg veins. In 30-40 days, these developments became more pronounced and were followed by a relative stabilization of hemodynamics at rest.

[The problem of artificial gravity: the present status and possible approaches].

The author reviews the Russian and international literature on the potentialities of artificial gravity in extended piloted space flights, especially in view of the declared initiatives to set forth on exploration missions in the first part of this century. Physical deconditioning and loss of tolerance to the gravitational loads consistently have their effects on cosmonauts despite the large assortment of in-flight preventive procedures. Effectiveness of artificial gravity generated by the short-arm centrifuge (SAC) has been assessed in experiments simulating the physiological consequences of microgravity by immersion or HDT, and flown aboard the dedicated satellites.

[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.

[Hemodynamic shifts in humans under the conditions of prolonged microgravity and the role of hypovolemia].

Purpose of this work was to elicit the role of hypovolemia in the development of hemodynamic shifts and loss of orthostatic tolerance in humans during prolonged space flights (PSF). Correlation analysis of the data of in-flight ultrasonic investigations of hemodynamics in resting cosmonauts and bio-impedance measurements of body liquids in different periods during PSF pointed out that changes in the left ventricle filling and renal artery resistance (Rren) reflect the degree of hypovolemia with r = 0.95.

[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.

[Effect of prophylactic device "Braslet" on hemodynamic changes during long-term missions to orbital station Mir].

The benefit from occlusive cuffs (prophylactic device Braslet) to human hemodynamics was evaluated in seven cosmonauts on long-term Mir missions using the ultrasonic technique (Echography and Doppler). Braslet had a positive effect on cosmonauts" state of health during the first month of flight. Improvement of cerebral hemodynamics was attested objectively by reduction of venous congestion.

[Possibility to predict cosmonauts' orthostatic tolerance following short-and long-term space flights].

According to the analysis of the data of active and passive orthostatic tolerance (OST) testing before and after 67 short- (SSF) and 53 long-term (LSF) space flights OST declined in all the cosmonauts regardless of flight length. Active testing on R+1 after SSF (7 to 25 d) and LSF (49 to 438 d) attested OST loss by 33% and 48%, respectively. Full OST recovery following SSF and LSF was observed in a week and 1.

[Peculiar physiological reactions to +Gx loads of nonprofessional members of short-term missions to the ISS].

Physiological reactions to +Gx loads of 10 nonprofessional members of 8 to 12-d. missions to the ISS some of whom had partial health defciency were compared with data about space station MIR cosmonauts (n=10) who participated in flights of similar duration but were qualified as essentially healthy. Age of the ISS visitors varied between 29 and 60 years, whereas the MIR cosmonauts were 31 to 49 years old.

[Rearrangement of the hemodynamic mechanisms of orthostatic tolerance of humans on long-term space missions].

Orthostatic tolerance (OT) was evaluated in 25 cosmonauts using the traditional standing test before and after space fights of about six months in length; 15 cosmonauts of this group were also subjected to ultrasonic investigation during the lower body negative pressure test before, during and after long-term SF. Efficiency of the OT vascular mechanisms was gradually falling and stabilized at the end of six-month SF at a level significantly below pre-flight level. Post-flight OT recovery took longer time as compared with short-term SF suggesting more profound shifts in the vascular control system.

[+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.

[Shifts in human venous hemodynamics in long-term space flight].

Veins and venous hemodynamics before, during and after long-term space flights (SF) were evaluated with the ultrasonic (B-scan, Doppler) techniques and occlusion plethysmography. Fifteen cosmonauts were investigated in eight SFs of about 6 months in duration. In three SFs, 30 investigations of the main veins in different parts of the body were fulfilled with participation of 7 cosmonauts.

[Relationship between the hemodynamic disorders in cosmonauts on short-term space flights and orthostatic stability].

Comparative investigation of the hemodynamic responses of cosmonauts at rest, during occlusive leg plethysmography, and LBNP in relatively short (less than a month) space flights were performed to tie up these measurements with post-landing orthostatic stability (OS). The decreased LBNP tolerance in flight that correlated later on with impaired reactions to both active and passive orthostatic testing are attributed, among other reasons, to deficient vasoconstriction of the main arteries and over-extendibility of veins in the lower extremities. Results of ultrasonic investigations of hemodynamics during LBNP tests before and after space flight and data of leg venous extension in SF can and should be used in predicting cosmonaut's orthostatic status post flight.

[Correlation of the cosmonauts' physiological reactions to +Gx loads during deorbit with the hemodynamic shifts in the period of short-term microgravity].

Physiological reactions of four cosmonauts to +Gx during the descent after short-term (less than 30 d) space flights were correlated with the hemodynamic shifts developed previously during the LBNP test and occlusive plethysmography in microgravity. The cosmonauts who had exhibited a sharp decrease in cerebral circulation during the in-flight LBNP tests showed signs of deteriorated cerebral blood flow (vertigo, weakness, hyperhydration) at the attempt to assume the vertical posture and to climb out of the landing module. Also, the cosmonauts found to have the arterial and venous tone significantly dropped in microgravity, suffered petechial hemorrhages in the back integument during the exposure to +Gx.

[Effects of occlusive cuffs "Braslet" on crew hemodynamics in short space flights and orthostatic stability post flight].

Effects of prophylactic device Braslet (occlusive cuffs wrapped around the calf) on hemodynamics were studied at rest and during the LBNP test during and on orthostatic stability post short (one-month) space flights. The ultrasonic procedure was applied to seven cosmonauts who had and six cosmonauts who had not worn the cuffs while in orbit. The device markedly alleviated the subjective feeling of discomfort caused by blood shift toward the cranial end at the beginning of adaptation to microgravity.

[The short-arm centrifuge: history and possible uses in cosmonautics and health care services].

The review has the objective to analyze applicability of short-radius centrifuges (SAC) in clinical practice. Attempts to treat with centrifuges were made already in the XVIIIth century by E. Darwin (1794) and then E.

[The problem of creation of artificial gravity with the use of a short-radius centrifuge for medical support of interplanetary piloted missions].

On the evidence of orbital flights, the system of countermeasures against the effects of microgravity does not fully make for deconditioning of a number of human organs and systems and recovery of preflight physical status and working ability of members of long-term missions takes 1.5 to 2 mos. of the post-flight rehabilitation.

[Effects of centrifugation-related artificial gravity on the human organism. Positive and negative effects].

Data of investigations of the artificial gravity issues in centrifuge experiments in Russian, USA and Japan over the past 40 years were analyzed. Periodic +Gz centrifugation was used to prevent or eliminate body deconditioning after 3- to 56-d simulated microgravity, and to increase the body functional reserve (orthostatic stability) in ordinary life. Positive effects included prevention of a decline of gravitational stability and reduction or averting the negative effects of simulated microgravity on various physiological systems.

[G-tolerance of female cosmonauts during descent in space flights of 8 up to 169 days in duration].

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).

[The effect of G-loads on gravity tolerance of monkeys Macaca rhesus during antiorthostatic hypokinesia].

Reported are results of 200 centrifuge runs of 24 monkeys Macaca mulatta. Microgravity effects were simulated by 4-wk immobilization with the head tilted down at -6 degrees. The investigation was divided into two series.