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Biomedical subjects

E M Nikolaenko

Publications and source records attributed to E M Nikolaenko.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

[Intermittent positive pressure ventilation of the lungs with the PO-6 respirator].

A modified Soviet ventilator PO-6 is presented suitable for performing intermittent mandatory ventilation (IMV) in combination with continuous positive airway pressure ventilation (CPAP). Some requirements for hardware necessary to realize IMV and CPAP modes are specified, and a critical evaluation of capabilities and disadvantages of the modified design is given in a view of these requirements.

Intermittent Positive-Pressure Ventilation↗
PubMedDate not supplied

[Central circulation in the healthy human being during 7 days of head-down tilt and decompression of different body areas].

The effect of 7-day head-down tilt (-15 degrees) and decompression of various body parts (lower body-LBNP, upper body in the area of the hydrostatically indifferent point-UBNP, and local negative pressure applied to both calves-LNP) on central circulation was investigated on eight healthy test subjects who, for 10 days, had catheters (Swan-Ganz) implanted into the pulmonary and radial arteries. It was shown that, when calculated by square centimeter of the decompression area, the effect of UBNP on central venous pressure (CVP) and pulmonary artery pressure (PAP) was 3-4 times greater than that of LBNP or LNP. This indicates a high sensitivity of this body part to the exposure. During the 7-day study, CVP and PAP showed the most distinct changes. By the 7th hour of the head-down tilt study, CVP remained unchanged and systolic PAP increased by 5.5 mm Hg (27%) (p less than 0.05). This was paralleled by a decrease of plasma aldosterone and renin. By the 2nd day of the study, CVP and PAP were close to the pretest level; on the 3rd day, they began to decline and remained about 3 mm Hg lower than the pretest values to the end of the study (p less than 0.05). During this same period, the contractility of the right heart (the mean rate of right ventricular pressure increment) decreased by 34% (p less than 0.05) and its work by 27% (p less than 0.05). By the 24th hour after the study (the recovery period), CVP and PAP were close to the pretest values, whereas heart rate, cardiac index and oxygen tension in the mixed venous blood were significantly higher than the pretest values (p less than 0.05). The factors responsible for these changes and the potential application of the catheterization technique in biomedical investigations during real space flight are discussed.

Adult↗
PubMedDate not supplied

[Water content of the lungs during 7-day anti-orthostatic hypokinesia].

The time-course variation of the water content of the lungs of seven male volunteers were examined during 7-day head-down tilt (at -15 degrees). As compared to the horizontal subjects, the tilted subjects showed a significant increase in the water content from 557 +/- 19 ml to 612 +/- +/- 63 ml by the 7th hour of the tilt. Later on the parameter gradually declined and on tilt day 7 almost returned to the pretest level, i.e., 567 +/- 46 ml. This increase in the water content during the first hours of the exposure can be attributed to the hydrostatic factors: higher pulmonary artery pressure and higher cardiac output. The increase in the water content on tilt days 3-7 can be associated with changes in the permeability of lung capillaries, drainage function of the lymphatic system of the lungs, and colloidal-osmotic pressure in the perivascular space of the lungs.

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↗