[The dynamic circulatory reaction of pilots to the standard test].

The examination of cardiovascular system in pilots in the process of their training has shown that the Valsalva test can execute the function of a slight or strong irritant with further changes in hemodynamics, particularly in the frequency of systoles and arterial pressure. These changes are accompanied by the shifts of cardiac volume per minute from hypo to hyper reaction. A correlation was disclosed between the reaction in the frequency of systoles and cardiac volume per minute which can be studied from the point of view of adaptation of blood circulation system to the factors of physical loads.

[Method for predicting danger induced by longitudinal accelerations in the 'head-pelvis' direction].

The paper deals with the results of the studies aimed to validate the criterion of prediction of human tolerance to longitudinal tailward accelerations on the basis of structural changes in cardiac rhythm recorded directly during exposure. The experiments have been done on centrifuge with recording the sequences of cardiac intervals at rest and each stage of exposure with successively increasing intensity. Representation of basic information as two-dimensional distributions of cardiointerval durations based on the autocorrelation rhythmography method has been used.

[Hemodynamic types in pilots and their clinical and expert-evaluation significance].

At the present time two approaches to the hemodynamics types can be distinguished in the literature: some authors maintain that they are variants of the norm, while others claim that they emerge in the course of disease. The purpose of the present investigation was to study the different viewpoints and to clarity the clinical and diagnostic role of hemodynamics types in aviation medicine. Altogether 293 pilots were examined, 49 of which were essentially healthy and 244 had various cardiovascular pathologies.

[Venous pressure in the jugular vein system and the efficiency of venous return to the right heart during 120-day antiorthostatic hypokinesia].

Study of time-course variations of venous pressure in the jugular veins can be used to identify individual adaptation to prolonged head-down tilt. The method of measuring blood return to the right heart presented here can be employed to evaluate the efficacy of countermeasures during head-down tilt and to predict orthostatic tolerance after it.

[Nature of the regulation of blood circulation in pilots].

Dynamic observations over a group of pilots within a working week during three months have shown that blood pressure increases to meet the requirements via a higher cardiac output. When stresses grow and fatigue sets in, the pattern of circulation regulation changes so that elevated blood pressure is maintained due to an increased peripheral resistance. Differential approach to the pattern of blood pressure regulation makes it possible to assess the degree of circulation adaptation to various work loads.

[Factor analysis of reactions to lower body negative pressure on the earth and during space flight].

The method of main components was used to examine separately the cosmonauts' responses to LBNP tests on the ground and in space flight. The factor structures of the ground- and flight data did not show significant differences. In both cases the first factor can be termed the factor of venous return and the second, the factor of the cardiac state.

[Study of the variations in cardiovascular system indicators using the main component method].

The main component method was used to analyze measurements of cardiovascular parameters taken in 14 healthy operators at rest. The entire sample included 237 observations. Each observation was characterized by the deviation of heart rate, mean blood pressure and stroke volume from individual data points.

[Changes in cardiac output and orthostatic tolerance of astronauts].

Examinations of 14 cosmonauts who performed orbital flights of 14 to 175 days were used to correlate cardiac output (CO) inflight with orthostatic tolerance and LBNP reactions postflight. In 3 crewmembers CO was lower than or close to the preflight level. In 4 cosmonauts CO was higher thant preflight.

[Comparative evaluation of the circulatory reaction during work in weightlessness and in the mockup of the Saliut station].

Comparative evaluations of circulation responses of 22 operators and 13 cosmonauts to simulated and real flights onboard Salyut station revealed significant differences. By the end of flight cardiovascular responses of the operators showed signs of their increased conditioning, whereas the cosmonauts exhibited symptoms of circulation tension, which were particularly expressed during the first week and by the end of flight. Operators' activities in an orbital station mockup cannot be considered an adequate model for cardiovascular studies.

[Comparison of direct and indirect methods of determining cardiac output].

In anesthetized dogs cardiac output was measured directly (by the method of Fick and by electromagnetic flowmetry) and indirectly (by the method of Bremser-Ranke and by rheography). The measurements were carried out before and after drug tests. The absolute values of cardiac output at rest differed depending on the method used.

[LBNP test reactions of Salyut-5 orbital station crew members].

During the 49-day mission (first expedition) the Commander did not show a decline in LBNP tolerance, whereas the Flight-Engineer showed a progressive decrease in LBNP tolerance beginning with Mission Day 23. During the 17-day mission (second expedition) the Flight-Engineer exhibited greater cardiovascular reactions to LBNP than the Commander. Postflight examinations confirmed the observations made in the weightless state.

[Hemodynamics and the phase structure of the cardiac cycle in the 1st crew members of Saliut-5 at rest].

In the Salyut-5 flight studies of circulatory functions were continued. Heart rate, arterial pressure, time intervals of the left and right ventricles were measured at rest. Peripheral resistance and cardiac output were calculated.

[Blood circulation under physical load in the crew members of the 1st Saliut-6 base expedition].

During the 96-day flight aboard the Salyut-6 station the crewmembers showed a satisfactory response to bicycle ergometry of moderate load. However, cardiovascular regulation during exercise declined, particularly by the end of the first and the beginning of the second month. This was mainly associated with deconditioning due to an inadequate work load.

[Hemodynamic and cardiac cycle phase structure study of the Saliut-4 crew].

The paper gives the results of physical examinations of P.I. Klimuk and V.

[Dynamics of the blood circulatory indices in the crew of the Saliut space station in a functional test under physical load].

On the 4th, 9th, 16th and 21st days of the "Salyut" mission the crewmembers performed exercises with a load of about 1100 kgm. The results were compared with those obtained on the Earth. Immediately after the tests the crewmembers showed an increased heart rate and greater changes in the diastolic and pulse pressure, cardiac output and left ventricular ejection time.

[Circulatory studies in LBNP on board the "Saliut-4" orbital station].

Orthostatic tolerance of the Salyut-4 crewmembers was measured by means of LBNP tests (--25 mm Hg for 2 min and --35 mm Hg for subsequent 3 min). Orthostatic tolerance decreased, remaining, however, satisfactory throughout the 2-month flight. During LBNP tests the pattern of most cardiovascular changes inflight and on the earth was similar.