[Prevention of altitude decompression sickness during simulation of egress from the cabin of space vehicle with hypobaric artificial atmosphere]. / Profilaktika vysotnoi dekompressionnoi bolezni pri imitatsii vykhodov iz kabiny kosmicheskogo korablia s gipobaricheskoi iskusstvennoi gazovoi atmosferoi.

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. In all, 115 experiments were performed. Twenty-four hours in HA at 93 kPa and subsequent transition to 37 kPa led up to development of ADS symptoms by one subject in one of 27 experiments (3.7%), and emergence of venous gas bubbles (USI) with the intensity of 2, 70, and 19 points by the Spenser scale in 9 experiments (33.3%). Lower HA pressures (86 kPa, 80 kPa and 73 kPa) did not give rise to ADS though the occurrence of venous GB distinctly tended downward (30.6%, 14.3% and 11.8%) and so did the intensity of their entry into the pulmonary circulation (2, 40, 18 points; 1, 80, 19 points, and 2, 00, 15 points, respectively). Minimal ADS risk was observed in HA at 80 kPa and 73 kPa and did not reach 4% at the confidence level of 95%.

[The assessment of the risk of altitude decompression sickness during simulation of repeated (with 12 hour interval) exits into open space]. / Otsenka riska vysotnoi dekompressionnoi bolezni pri imitatsii povtornykh (s 12-chasovym intervalom) vykhodov v otkrytyi kosmos]

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. None of 24 "ascents" produced clinical signs of ADS. Comparison of the data concerning frequency and time points of detection by ultrasonic Doppler equipment of gas bubbles (GB) in the venous bed during decompression with initial, maximal and mean values of US signal intensity failed to state a significant difference between them. Data of the investigation were confronted with anticipated length of GB dispersion in body tissues.

[Effects of isolated and combined effects of a constant magnetic field and antiorthostatic hypokinesia on central hemodynamics in rats]. / Vliianie izolirovannogo i kombinirovannogo deistviia postoiannogo magnitnogo polia i antiortostaticheskoi gipokinezii na tsentral'nuiu gemodinamiku u krys.

The effect of a constant magnetic field on central circulation of rats was investigated during their exposure to antiorthostatic hypokinesia. Circulation parameters were measured by impedance rheoplethysmography. It was found that 3-hour exposure to a 0.4 T magnetic field did not produce a significant effect on central circulation, whereas exposure to hypokinesia caused substantial changes which included decreases of heart rate, stroke volume and cardiac output. During a combined exposure to a constant magnetic field and antiorthostatic hypokinesia, the magnetic field exerted a beneficial effect on central circulation.

[Relation between the status of central hemodynamics in the monkey in the postoperative period and the conditions of its maintenance prior to the surgical procedure]. / Sostoianie tsentral'noi gemodinamiki u obez'ian v posleoperatsionnyi period v zavisimosti ot uslovii soderzhaniia ikh do operativnogo vmeshatel'stva.

The pumping and contractile cardiac function of monkeys was examined at different time intervals after electrode and transducer implantation. The study was carried out using 26 rhesus monkeys under ketalar anesthesia. The effect this surgical intervention on intracardiac hemodynamics depended on the initial health state of the animals. Prior to operation the pumping function declined due to diminished motor activity of the animals. It remained decreased to a greater extent 10-15 days after operation. When normal motor activity was allowed even for a short time before surgical implantation, this was sufficient for the normalization of the cardiovascular function. In view of these observations, we should be very cautious to expose monkeys to diminished motor activity for long periods of time.

[Ultrasonic echolocation of soft tissues in dogs during decompression]. / Ul'trazvukovaia ékholokatsiia miagkikh tkanei u sobak pri dekompressii.

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. The concomitant echographic changes pointed to the formation of extra- and intravascular gas bubbles in the above tissues. The bubbles could be identified visually in the nearest echographic band because the instrumentation used made it possible to eliminate the background image of structural inhomogeneities of the tissue layer.

[Detection of gas bubbles in the pulmonary artery and aorta of dogs by ultrasonic echography after intravenous infusion of air]. / Registratsiia gazovykh puzyrkov v legochnoi arterii i aorte sobak sredstvami ul'trazvukovoi ekhografii pri vnutrivennoi infuzii vozdukha.

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. It is postulated that gas bubbles formed in the animal and human body during decompression may pass from the venous into the arterial bed not only through shunts but also through lung capillaries.

[Verification of the effectiveness of preventing altitude decompression disorders by nitrogen desaturation of the organism through surrounding the body with an oxygen envelope]. / Proverka éffektivnosti profilaktiki vysotnykh dekompressionnykh rasstroistv putem desaturatsii organizma ot azota pri okruzhenii tela kislorodnoi obolochkoi.

The purpose of the present investigation was to assess the effect of nitrogen penetrating the human skin from the ambient atmosphere on the level of denitrogenization achieved by oxygen breathing. Young healthy male test subjects were exposed to denitrogenization for 5, 6 or 8 hours by breathing pure oxygen. During that time they wore an oxygen filled suit. Then they ascended an altitude of 11,000 m and remained there for 6 hours doing exercises. Altogether 38 investigations were carried out on 13 subjects, with and without a pressure suit. The investigation did not demonstrate any specific differences in the occurrence of decompression disease at an altitude of 11,000 m with or without a pressure suit. Nitrogen penetrating through the skin from the ambient atmosphere during oxygen breathing did not influence the level of denitrogenization.