A Technique of Forced Expiratory Noise Time Evaluation Provides Distinguishing Human Pulmonary Ventilation Dynamics During Long-Term Head-Down and Head-Up Tilt Bed Rest Tests Simulating Micro and Lunar Gravity.

Estimating the effect of microgravity/hypogravity on pulmonary ventilation function remains topical. Recently developed acoustic techniques based on the evaluation of the forced expiratory noise time (FETa) were hypothesized to be a promising tool for this aim. The aim of the protocol is to study the effect of two different modalities of bed rest space simulations (microgravity and lunar gravity) on FETa and spirometric indices.

Effect of Simulated Microgravity and Lunar Gravity on Human Inspiratory Muscle Function: 'Selena-T' 2015 Study.

As a part of the multi-disciplinary "SELENA-T"-2015 Bed Rest Study, we investigated the pattern of inspiratory muscles fatigue in 22 healthy male subjects during incremental exercise test to exhaustion before and after 21 days of hypokinesia evoked by bed rest. Hypokinesia consisted of head-down bed rest (HDBR) at a minus 6° angle, simulating microgravity present on orbiting spacecraft, in 10 subjects. The remaining 12 subjects spent the first 5 days of hypokinesia in HDBR position and the subsequent 16 days in head-up bed rest (HUBR) at a plus 9.

A Method of Ground Simulation of Physiological Effects of Hypogravity on Humans.

A novel method of ground simulation in humans of physiological effects induced by the stay on the surface of celestial bodies with hypogravity was developed and successfully tested. This method is based on the change of gravity force angle, which decreases the gravitational component of the blood hydrostatic pressure characteristic of human vertical posture on the Earth and the load-weight onto the locomotor apparatus to the lower values expected at celestial bodies with hypogravity. The methodological requirements for ground simulation of the physiological effects of lunar gravity on human body are specified and substantiated by theoretical calculations.

[Heart rate and energy expenditure during extravehicular activity in different time of day].

The article discusses the comparative heart rate (HR) characteristics associated with day and night extravehicular activities (EVA). HR was commonly higher in the night but not in the daytime. Presumably, the reason is psychological and physiological challenges of the night work on the background of natural performance decrement.

[The effect of sensory stimuli of varying modality on the human body functioning and indices of tense muscular activity].

The work had a purpose to study benefits of aromatic blends of tonic and relaxing essences and functional music on some of the psychophysiological properties of the human functional state and motor activeity. Participants were 30 sprinters (18-22 y.o.

[Evaluation of benefits of the course of positive pressure breathing training on exercise performance].

The purpose was to evaluate effects of muscle training combined with positive pressure breathing on exercise performance of 16 runners at the age of 18-20. All subjects had the first or second-class sport qualification. The 4-wk.

The main results of EVA medical support on the Mir Space Station.

The aim of this paper is to review the main results of medical support of 78 two-person extravehicular activities (EVAs) which have been conducted in the Mir Space Program. Thirty-six male crewmembers participated in these EVAs. Maximum length of a space walk was equal to 7 h 14 min.

[Classification of altitude decompression sickness].

The article is devoted to the discussion of principles of and approaches to classification of altitude decompression sickness (DCS), one of the most methodically formidable aspects of the problem. Based on his own multiyear experience in altitude DCS investigations and critical review of literature, the author reasons his concept of clinical classification of altitude DCS. The author's concept places emphasis on obligatory consideration of three stages in DCS development: A--pre-disease (the premorbid syndrome), B--uncomplicated (light) and C--complicated (severe) forms.

Fatty acid composition of plasma lipids and erythrocyte membranes during simulated extravehicular activity.

Ten subjects (from 27 to 41 years) have been participated in 32 experiments. They were decompressed from ground level to 40-35 kPa in altitude chamber when breathed 100% oxygen by mask and performed repeated cycles of exercises (3.0 Kcal/min).

[Prevention of altitude decompression sickness during simulation of egress from the cabin of space vehicle with hypobaric artificial atmosphere].

Based on the proposed semiempiric nomograms, the study was aimed at selection and investigation of normoxic N2-O2 hypobaric atmosphere (HA) at 93-73 kPa, and evaluation of effectiveness of the gas mixture against the altitude decompression sickness (ADS) during 6-hr simulation of extravehicular activities at 37 kPa without prebreathing. Subjects were 22 healthy males from 20 to 50 yr. old.

[The assessment of the risk of altitude decompression sickness during simulation of repeated (with 12 hour interval) exits into open space].

Purpose of the investigation was to assess contribution of repeated (with a 12-hr interval) decompression to the risk of altitude decompression sickness (ADS) by simulation of 6-hr extravehicular activities (EVA) of space crewmembers in altitude chamber. The protocol included "ascents" of 6 essentially healthy male subjects at the age of 24 to 51 to the altitude of 7,600 m (37 kPa) following 30-min prebreathing (elimination of nitrogen from the body by breathing pure oxygen through a mask at the ambient pressure of 73 kPa = 2,600 m). Each subject participated in 2 experimental exposures: first initial and then repeated decompression.

[The monitoring of gas bubbles with a pulsed Doppler ultrasonic locator in humans working in a space suit].

Presented are results of gas bubbles monitoring in decompressed humans with the use of an ultrasonic pulse-Doppler locator (PDL). Unlike the classic Doppler bubbles detectors with continuous US emission, PDL is adjusted for reception of echo from a chosen volume of the right ventricle cavity; thus, the clutter due to cardiac beats and human locomotion is successfully rejected. During simulation of Russian EVAs, venous gas bubbles were detected in 3 out of 5 experiments with test-subjects clothed in everyday wear and in 2 out of 3 experiments with suited test-subjects.

[Decompression sickness-one of the vital problems of aerospace medicine].

The author reviews the literature on decompression sickness (DCS) constituting one of the major problems of aerospace medicine. He speculates on the terms describing this health condition and offers the retrospective of hypothesised causes for DCS development. The paper outlines main DCS symptoms and reports statistics on the DCS incidence rate in flying personnel when piloting aircraft and training in altitude chambers, and in volunteered test-subjects during physiological experiments with simulated ascents in order to mimic the extravehicular activities of cosmonauts and to test the altitude gear.

[Fatty acid composition of the lipids in human blood plasma and erythrocyte membranes during simulation of extravehicular activities of cosmonauts].

Dynamics of the lipoacidic content of total plasma lipids and erythtocyte membranes was studied in 32 experiments with ten apparently healthy male subjects aged 27 to 41 years who were exposed to repeated decompression from the normal ground down to 40-35 kPa. For two hours of exposure to lowered pressure the subjects were breathing pure oxygen in mask and performing incremental physical work mimicking loading of the upper extremities of cosmonauts doing extravehicular activities (EVA) at the energy cost of 3 kcal/min. Decompression sessions were repeated with intervals from 3 to 5 days.

[Analysis of decompression safety during extravehicular activity of astronauts in the light of probability theory].

Objectives of the study were comparative assessment of the risk of decompression sickness (DCS) in human subjects during shirt-sleeve simulation of extravehicular activity (EVA) following Russian and U.S. protocols, and analysis of causes of the difference between real and simulated EVA decompression safety.

The feasibility of Doppler monitoring during EVA.

During extravehicular activities (EVA) outside the spacecraft, astronauts have to work under reduced pressure in a space suit. This pressure reduction induces the risk of decompression sickness (DCS) by the formation of gas bubbles from excess nitrogen dissolved in the organism by breathing air at normal pressure. Under laboratory conditions the gas bubbles moving in the blood stream can be detected by the non-invasive ultrasonic Doppler method.

[Effect of decompression on the compliment system].

Decompression effects on the complement system were studied in healthy male volunteers who made 39 "ascents" to 7000-9000 m and 13 "descents" to 30 m. Hemolytic activity of the complement system components was determined in the blood serum taken from the cubital vein of the subjects immediately before and after decompression. The results of this study showed that in the absence symptoms of decompression sickness (DCS) and doppler-detected gas bubbles (GB) the subjects reduced activities of C1 and C4.

[The ultrasonic location of gas bubbles in the human bloodstream during work in a spacesuit].

The results of testing a procedure of ultrasonic location of the gas bubbles (GB) in man during space suit operations to simulate an extravehicular activity (EVA) are presented. Doppler echotachocardiograph "Rhythm" operating at ultrasonic frequency of 1.76 mHz was used as a GB detector.

[Central and general hemodynamics in healthy persons during simulated weightlessness].

The pumping and contractile functions of the left ventricle were investigated during combined exposure to water immersion and head-down tilt (at -6 degrees) that simulated microgravity. This 7-day exposure caused noticeable changes in central and systemic circulation which developed as a function of time. It is assumed that the deficiency of venous blood return seen on test days 1-3 was a compensatory response to initial blood displacement which was induced by a reduction of the circulating blood volume.

[Reliability and effectiveness of monitoring the stroke and minute volume of the heart by Kubicek's rheographic method].

Simultaneous measurements by the Fick direct method and the Kubicek rheographic method of cardiac output of 20 men with ischemic heart disease have shown that both methods are well correlated (r = 0.76, k = 0.92, n = 41).

[Ultrasonic echolocation of soft tissues in dogs during decompression].

Ultrasonic location of femoral soft tissues of anesthetized dogs was performed using a modified unit UZKAP-3. The animals were exposed to 0.5 mPa for 2 hours and then to decompression to sea level pressure.

[Detection of gas bubbles in the pulmonary artery and aorta of dogs by ultrasonic echography after intravenous infusion of air].

The transducer and receiving amplifier of a standard ultrasonic echocardiograph were modified to develop a device for detecting unmasked echocardiographic images of gas bubbles in blood vessels. This device was employed to detect gas bubbles passing from the venous to the arterial bed via lungs in anesthesized and thoracotomized dogs during air intravenous infusion. Gas bubbles entered the aorta when the dose of infused airw as 12-15 ml.