[Change in the hemodynamics and phase structure of the cardiac cycle in the crew of the 2d "Saliut-4" expedition]. / Izmenenie gemodinamiki i fazovoi struktury serdechnogo tsikla u ékipazha vtoroi ékspeditsii "Saliut-4"

Medical examinations of the Salyut-4 crewmembers included bicycle ergometry tests. During the tests the heart rate and the time intervals of the left ventricle were measured. On the 46th flight day the arterial pressure, cardiac output and peripheral resistance were also determined. In the course of the 63-day flight responses to the 5 min workload of 2100-2200 kgm did not differ essentially from the preflight level, and did not increase with the flight time. Circulation changes noted in zero-g and upon return to I g were similar and can be accounted for by a reduction of the circulating blood volume. Inflight during the first minutes after the workload more marked changes in the cardiac output and cycle were detected. This can be attributed to a relatively stronger effect of blood pooling in working muscles on the venous return of the blood. On the 3rd postflight day the arterial pressure and the velocity of the aortal propagation of the pulse wave were higher.

[Dynamics of the venous circulation in the cosmonauts of the 2d "Saliut-4" expedition]. / Dinamika venoznogo krovoobrashcheniia u kosmonavtov vtoroi ékspeditsii "Saliut-4"

During the first month of the orbital flight the cosmonauts showed an increase in the blood pressure and filling in the jugular veins whereas during the second month they exhibited a decrease in these parameters below the preflight level. Throughout the mission the pressure in the pulmonary artery remained slightly increased. The time of contractions of the right heart changed. The changes in the blood pressure and filling in the jugular veins can be explained by blood pooling there and subsequent extravasation of blood into the abdominal cavity.

[Circulatory studies in LBNP on board the "Saliut-4" orbital station]. / Issledovaniia krovoobrashcheniia pri ODNT na orbital'noi stantsii "Saliut-4".

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. In weightlessness heart rate increased reaching maximum preflight values; cardiac output and stroke volume decreased noticeably; the systolic time interval changed significantly. The recommended regimen of LBNP did not deteriorate the health state of the crewmembers and was adequate to predict their orthostatic tolerance. Criteria for the evaluation of the health condition of space crewmembers were developed.