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Biomedical subjects

V E Katkov

Publications and source records attributed to V E Katkov.

50 records · Page 3Linked to original sources
PubMedDate not supplied

[Coronary circulation in healthy men during postural changes and decompression of the lower half of the body].

The effect of postural changes (ortho- and antiorthostatic tests) and LBNP on coronary circulation was investigated in 11 healthy male test subjects. Volume blood flow velocity and pressure were measured and blood flowing from the heart was withdrawn using a Ganz catheter implanted into the coronary sinus. A thin Teflon catheter was implanted into the brachial artery. When the test subjects were transferred from the recumbent to the head-up position, their left ventricular oxygen consumption decreased by 3.2 ml/min (21%) and coronary blood flow by 23.8 ml/min (19%), while coronary vascular resistance increased by 32%. When the test subjects were transferred from the head-up to the head-down position (at -15 degrees), coronary oxygen consumption and blood flow increased by 5.5 (46%) and 45.3 (44%) ml/min, respectively, and coronary resistance decreased by 36%. In this situation the LBNP test (-30 mm Hg for 20 min) caused a reduction in oxygen consumption and coronary blood flow by 4.4 (25%) and 37.3 (25% 7 ml/min, respectively, and an increase in coronary resistance by 58%.

Adult↗
PubMedDate not supplied

[Closing volume of the respiratory airways and total lung capacity during 7-day antiorthostatic hypokinesis].

By mass spectrography and pneumotachography structural variations in total lung capacity (TLC) were investigated in 7 test subjects during 7-day head-down tilt at -15 degrees. By the 7th hour of head-down tilt TLC, vital lung capacity (VLC), functional residual capacity (FRC) and residual volume (RV) decreased significantly and closing volume (CV) increased insignificantly. The CV/FRC ratio grew from 0.82 +/- 0.03 to 1.24 +/- 0.08 (P less than 0.01), indicating the closure of respiratory pathways in certain lung structures within the tidal volume. These changes in the TLC structure persisted till day 7 but the CV/FRC ratio fell down to 1.01 +/- 0.07. The above findings can clarify the mechanism responsible for a lower oxygenation of arterial blood in the head-down position. The expiratory closure of the airways within the tidal volume causes regional changes in alveolar ventilation and ventilation-perfusion relations and, consequently, a larger venous admixture and a smaller oxygen saturation of arterial blood.

Adult↗
PubMedDate not supplied

[Central blood circulation in the healthy human being during 7 days' head-down tilt hypokinesia].

The effect of 7-day head-down tilt (-15 degrees) and lower body negative pressure on circulation and oxidative metabolism was investigated on 13 healthy male test subjects. For 7-10 days they had Swan-Ganz catheters implanted in the pulmonary artery and a special cannula in the radial artery. The most marked changes were seen in the pulmonary artery pressure (PAP) and central venous pressure (CVP) that varied in a phase-like manner. By the 7th hour of bed rest the PAP increased significantly; this was followed by increases in the total lung resistance and the right ventricle function, as well as by a slight decrease of renin and aldosterone. Beginning with bed rest days 2 or 3 the PAP and CVP declined and remained lowered, as compared to the pretest level, till the end of bed rest. The responses to LBNP tests changed by bed rest day 2. Possible mechanisms of the above changes at rest and during LBNP tests are discussed.

Adult↗
PubMedDate not supplied

[Effect of negative pressure on the lower half of the body (the Chibis suit) and of local negative pressure on central circulation in the healthy human].

Catheters were chronically implanted into pulmonary and radial arteries of 8 healthy volunteers to examine the effect of lower body negative pressure (LBNP in the Chibis suit) and local negative pressure on the leg on central circulation, oxidative metabolism and acid-base equilibrium in the blood. In 1-hour head-down tests (at -20 degrees) the effect of two regimens of LBNP (at -30 and -60 mm Hg) and local negative pressure (at -50 and -100 mm Hg) was studied, each exposure averaging 15-20 min. Both LBNP and local negative pressure induced changes in central circulation that were similar qualitatively and dissimilar quantitatively. The use of regimen I of both exposures caused more marked changes than that of regimen II.

Acid-Base Equilibrium↗
PubMedDate not supplied

[Effect of negative pressure and occluding cuffs on the intravascular pressure in the lower extremity of the healthy human being].

The effect of local negative pressure on the leg (with a bladder sealed above the knee) and occlusion cuffs (located as close as possible to Poupart's ligament) on the leg intravascular pressure was investigated in recumbency. In two experimental runs 8 healthy volunteers participated. Each of the two exposures was used at two levels: local negative pressure at -50 and -100 mm Hg and occlusion cuffs at +40 and +60 mm Hg with the exposure time averaging 5-7 min. Catheters were inserted into the femoral artery and vein, and arteries and veins of the back of the foot. The arterial pressure remained unchanged during both exposures: local negative pressure and occlusion cuffs. Upon exposure to local negative pressure the venous pressure in the back of the foot (with respect to the atmospheric pressure) did not change and in the femoral vein decreased. Upon exposure to occlusion cuffs the venous pressure in the back of the foot increased noticeably and in the femoral vein decreased slightly. It is concluded that none of the exposures can reproduce the major gravitational effect on leg vessels, i.e. characteristic changes in gradients of the intravascular (transmural) pressure.

Adult↗
PubMedDate not supplied

[Pressure in the jugular vein and right atrium and the cerebral hemodynamics of the healthy human being exposed to postural effects].

Ten test subjects were catheterized and exposed to head-up and head-down tilts at 10, 30 and 75% for 5 min each to measure blood pressure in the upper bulb of the internal jugular vein and right atrium. Blood acid-base equilibrium, hemoglobin content and oxygen saturation were also determined. In the head-up position at 75 degrees the jugular pressure decreased, remaining positive (2.8 mm Hg) in most cases, whereas the atrial pressure fell down to reach the subatmospheric level. In the hea-down position the jugular pressure increased in proportion to the tilt angle, amounting to 32,2 mm Hg at 75 degrees; the atrial pressure changed in a different fashion: in 7 cases it increased and in 3 cases decreased. Throughout the test the oxygen arteriovenous difference in the brain and the acid-base equilibrium in the outflowing blood remained essentially unchanged. This reflects autoregulation of the cerebral blood flow and its adequacy to metabolic requirements.

Adult↗