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Biomedical subjects

A D Voskresenskiĭ

Publications and source records attributed to A D Voskresenskiĭ.

11 recordsLinked to original sources
PubMed2002

[Correlation between empirical and statistical indices of cardiovascular deconditioning in response to orthostatic exposures].

Data of heart rate and blood pressure from 26 astronauts during orthostatic testing before and after space flight and 15 healthy men during orthostatic testing before and after 10-days head-down tilt (HDT) were used to correlate two integral indices of cardiovascular deconditioning. The first, very simple index, was used earlier by Bungo M. W. et al. in order to ascertain the efficiency of peroral body dehydratation as a measure to prevent orthostatic intolerance in astronauts after space flight. This index sums up HR and BP variations from one orthosatic probe to another. The choice of the another index was based on our investigation of HDT effects on the healthy human cardiovascular system. This index was determined as a difference between linear discriminant function values separating distinctly groups of men with normal and lowered orthostatic tolerance. Analysis of regression showed a high correlation between these indices: 0.71 for the group of astronauts and 0.88 for the group of healthy men. The linear regression equations allowed calculate value of one index from value of the other with an admissible standard error.

Astronauts↗
PubMedDate not supplied

[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. The first two factors were responsible for about 60%, and the first three factors for 76-78% of data scatter. The observation that the factor structure remains unchanged indicates that LBNP reactions in space flight can be evaluated using the criteria applied on the Earth.

Blood Pressure↗
PubMedDate not supplied

[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. The latter were individual mean values of the above parameters recorded during the Valsalva maneuver. The first two main components were responsible for over 77% of total variance of signs. Visual analysis of observation distribution with respect to the components revealed small group and single data points situated peripherally at a distance from the major constellation of data points. With respect to the values in these groups it can be assumed that some of them correspond to the stressed state of the cardiovascular system. Two thirds of data points in the stressed groups are associated with the subjects who show a weak reaction to the Valsalva maneuver and one third corresponds to the true stressed state. Taking into account the Valsalva maneuver, the deviations from individual data points can be used to identify the stressed state of the cardiovascular system in healthy men at rest.

Blood Pressure↗
PubMedDate not supplied

[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. The remaining 7 crewmembers showed lower orthostatic tolerance and stronger LBNP reactions. The difference between mean CO values before and during flight was in negative correlation with orthostatic tolerance (r = -0.6) and in positive correlation with LBNP reactions (r = 0.7). The correlation coefficients were derived from small samples but an identical relationship between the two different tests with inflight CO variations gives evidence that such a relationship actually exists.

Adaptation, Physiological↗