Cardiovascular effects of anti-G suit and cooling garment during space shuttle re-entry and landing

BACKGROUND: Many cardiovascular changes associated with spaceflight reduce the ability of the cardiovascular system to oppose gravity on return to Earth, leaving astronauts susceptible to orthostatic hypotension during re-entry and landing. Consequently, an anti-G suit was developed to protect arterial pressure during re-entry. A liquid cooling garment (LCG) was then needed to alleviate the thermal stress resulting from use of the launch and entry suit. METHODS: We studied 34 astronauts on 22 flights (4-16 d). Subjects were studied 10 d before launch and on landing day. Preflight, crewmembers were suited with their anti-G suits set to the intended inflation for re-entry. Three consecutive measurements of heart rate and arterial pressure were obtained while seated and then again while standing. Three subjects who inflated the anti-G suits also donned the LCG for landing. Arterial pressure and heart rate were measured every 5 min during the de-orbit maneuver, through maximum G-loading (max-G) and touch down (TD). After TD, crew-members again initiated three seated measurements followed by three standing measurements. RESULTS: Astronauts with inflated anti-G suits had higher arterial pressure than those who did not have inflated anti-G suits during re-entry and landing (133.1 +/- 2.5/76.1 +/- 2.1 vs. 128.3 +/- 4.2/79.3 +/- 2.9, de-orbit; 157.3 +/- 4.5/102.1 +/- 3.6 vs. 145.2 +/- 10.5/95.7 + 5.5, max-G; 159.6 +/- 3.9/103.7 +/- 3.3 vs. 134.1 +/- 5.1/85.7 +/- 3.1, TD). In the group with inflated anti-G suits, those who also wore the LCG exhibited significantly lower heart rates than those who did not (75.7 +/- 11.5 vs. 86.5 +/- 6.2, de-orbit; 79.5 +/- 24.8 vs. 112.1 +/- 8.7, max-G; 84.7 +/- 8.0 vs. 110.5 +/- 7.9, TD). CONCLUSIONS: The anti-G suit is effective in supporting arterial pressure. The addition of the LCG lowers heart rate during re-entry.     

Compatible atmospheres for a space suit, space station, and shuttle based on physiological principles

Fundamental physiological principles have been invoked to design compatible environments for a space suit, space station, and the space craft used to transport the astronauts from Earth. These principles include the long-term memory of tissues for a bubble-provoking decompression, the intermittent nature of blood flow in the tight connective tissues(s) responsible for the bends whose incidence in aviators has been shown to be related to bubble volume by the Weibull distribution. In the overall design an astronaut breathing a mixture of 30% O2 in N2 for 4-5 h in a space craft at 11.9 psia can transfer to a space station filled with the same mix at 8.7 psia and, after a further 4-5 h, go EVA at any time without any oxygen prebreathing at any stage. The probable incidence of decompression sickness has been estimated as less than 0.5% using the present suit operating at 4.3 psia but the risk could be reduced to zero if the suit pressure were increased to 6.5 psia.     

飞行员配穿囊式抗荷服在不同代谢水平时的温度舒适性评定

目的　评价飞行员配穿囊式抗荷服在不同代谢水平、不同环境温度条件下的温度舒适性。　方法　 6名受试者分别以不同的代谢水平暴露于 2 0℃、2 5℃和 35℃环境 ,配穿装备为KH 3抗荷服和KH 7抗荷服。每次试验 70min。采用微小气候评定装置测量衣下温度和衣下潮湿率 ,并以 3种主观感觉评定温度舒适性。　结果　试验期间 ,Ⅲ组 (或Ⅳ组 )的衣下温度增值和衣下潮湿率增值均无显著性意义。Ⅰ组 (或Ⅱ组 )、Ⅴ组 (或Ⅵ组 )、Ⅶ组 (或Ⅷ组 )分别与Ⅲ组 (或Ⅳ组 )比较 ,衣下温度增值、衣下潮湿率增值均有显著或非常显著性意义 (P <0 .0 5或P <0 .0 1)。Ⅰ组 (或Ⅱ组 )与Ⅴ组 (或Ⅵ组 )的衣下温度增值、衣下潮湿率增值均有显著性意义 (P <0 .0 5 )。Ⅰ组～Ⅷ组的衣下温度、衣下潮湿率作比较 ,Ⅶ组 (或Ⅷ组 )与其它各组的增值均有非常显著性意义 (P <0 .0 1)。　结论　在一定的环境温度范围内 ,代谢水平可以比环境温度更能影响人体的温度舒适性。 2 0℃环境中 ,飞行员配穿KH 3抗荷服和KH 7抗荷服飞行时 ,衣下微小气候是不适宜的。在 2 5℃环境下从事低代谢率活动时 ,对温度舒适无显著性影响。 35℃环境中 ,即使从事低代谢水平活动 ,也将严重影响飞行员温度舒适。     

Explosive decompression of subjects up to a 20,000-m altitude using a two-pressure flying suit.

The RSAF two-pressure flying suit system to protect the pilot at high altitude has been tested from different medical safety aspects. To secure adequate alveolar oxygen pressure, the suit admits up to 70 mm Hg (9.3 kPa) positive pressure breathing by counter-pressure against the thorax and by a 3.2 times higher pressure in the anti-G suit. After 1 h of oxygen breathing, subjects were exposed to explosive decompression from an altitude of 9,000 m to 17,500 or 20,000 m in 0.5 s in a hypobaric chamber. No symptoms of decompression sickness or of alveolar rupture with gas embolism to the central nervous system were seen. Pulmonary X-rays after the test did not reveal any signs of lung rupture with extrapulmonary gas leakage. With the precordial Doppler ultrasound technique, intracardial gas bubbles (silent bubbles) could be detected only in one subject after explosive decompression to a 20,000-m altitude in the 10 experiments.     

Individual thermal profiles as a basis for comfort improvement in space and other environments

BACKGROUND: The development of individualized countermeasures to address problems in thermoregulation is of considerable importance for humans in space and other extreme environments. A methodology is presented for evaluating minimal/maximal heat flux from the total human body and specific body zones, and for assessing individual differences in the efficiency of heat exchange from these body areas. The goal is to apply this information to the design of individualized protective equipment. METHODS: A multi-compartment conductive plastic tubing liquid cooling/warming garment (LCWG) was developed. Inlet water temperatures of 8-45 degrees C were imposed sequentially to specific body areas while the remainder of the garment was maintained at 33 degrees C. RESULTS: There were significant differences in heat exchange level among body zones in both the 8 degrees and 45 degrees C temperature conditions (p < 0.001). The greatest amount of heat was absorbed/released by the following areas: thighs (8 degrees C: -2.12 +/- 0.14 kcal min(-1); 45 degrees C: +1.58 +/- 0.23); torso (8 degrees C: -2.12 +/- 0.13 kcal min(-1); 45 degrees C: +1.31 +/- 0.27); calves (8 degrees C: -1.59 +/- 0.26 kcal min(-1); 45 degrees C: +1.53 +/- 0.24); and forearms (8 degrees C: -1.67 +/- 0.29 kcal x min(-1); 45 degrees C: +1.45 +/- 0.20). These are primarily zones with relatively large muscle mass and adipose tissue. Calculation of absorption/release heat rates standardized per unit tube length and flow rate instead of zonal surface area covered showed that there was significantly greater heat transfer in the head, hands, and feet (p < 0.001). The areas in which there was considerable between-subject variability in rates of heat transfer and thus most informative for individual profile design were the torso, thighs, shoulders, and calves or forearms. CONCLUSIONS: The methodology developed is sensitive to individual differences in the process of heat exchange and variations in different body areas, depending on their size and tissue mass content. The design of individual thermal profiles is feasible for better comfort of astronauts on long-duration missions and personnel in other extreme environments.     

Corrosion control of steel components exposed to thermal cycling using radioactive tracers

The aim of the experiments presented in this paper was to choose from the project-recommended types of steel, the most suitable one for manufacturing the inner surfaces of the fire tube of an inert gas generator (IGG). Typically, such generators are used on oil tankers for maintaining an inert gas cushion above the oil's surface in order to prevent accidental combustion. For this approach, we employed the Thin Layer Activation (TLA) technique. Several steel samples have been activated either by 14 MeV proton or 8.5–12.5 MeV deuteron beams. The principle of measuring method, including the calibration procedure for transforming the resulted decreases in radioactivity into material loss data, have been presented in detail in the paper. The real workking conditions-exposure to H₂O, CO₂, and SO_x compounds (ca. 1–2.5% in regular Diesel oil) having temperatures up to 700°C were assured by mounting the steel samples in a similar tube to the one used offshore. For high accuracy results, the experiment required a dedicated calibration set-up, designed particularly for this application. The main outcome of the experiment was a classification of the different kinds of steels used (brands and/or manufacturers will not be specified in the paper) in accordance with the resistance to erosive corrosion induced by fuel-oil burning products.     

飞行员新型降温背心冷却效果的评定

目的评价一种以冰胶为制冷介质的降温背心的降温性能。方法试验环境温度为干球温度（Tdb）45℃，湿球温度（Twb）32℃（相对湿度50％）。受试者为6名男性青年。观察其加权平均皮肤温度（Ts）、躯干皮肤温度（Tt）、直肠温度、出汗量和综合热应激指数（CIHS），记录温度舒适性评价等级。结果对比受试者穿与不穿降温背心暴露热环境时的各项生理指标后，前者的各项生理指标均有显著和非常显著性降低，主观舒适性评分等级前者的也明显优于后者。但在使用降温背心过程中，存在受试者躯干局部皮肤温度偏低、感觉略凉的现象。结论该降温背心具有良好的降温性能。建议在重新设计时采取措施纠正躯干局部皮肤温度偏低的现象。     

Automatic opto-electronic control of patient position in radiotherapy for breast carcinoma

INTRODUCTION: We report on the technical and clinical validation of a system for real-time analytical control of patient position at simulation and treatment units in radiotherapy. MATERIAL AND METHODS: The positioning control system uses a technology for motion analysis consisting of an optical component (a pair of TV cameras) and of a unit for real-time image processing. The system can provide real-time (up to 100 times a second) three-dimensional (3D) coordinates of a set of passive markers (small plastic hemispheres, 5 mm O) previously positioned on the patient and located within the field of view of the system's TV cameras. The method for positioning quality control is based on the analytical comparison between the current positions of the set of markers placed on the patient's skin and a corresponding reference pattern, the latter acquired at the end of the simulation procedure or at the first irradiation session. The system was used at the Radiotherapy Division of the European Institute of Oncology for the analytical control of repositioning in three patients submitted to irradiation after conservative surgery (quadrantectomy) for breast cancer. This showed the clinical feasibility of both the technology and the method, and permitted to quantify improvement in patient positioning relative to current repositioning procedures. In particular, the possibility to evaluate the patient's breathing phases allowed to distinguish the different factors (repositioning inaccuracies and cyclic and random patient movements) contributing to global localization errors. RESULTS: This method is independent of physical and geometrical irradiation parameters and permits efficient real-time quantitative control of specific repositioning quality and of actual patient immobility during irradiation. Assessment of the accuracy of conventional repositioning methods based on laser alignment showed a fair performance of the optical centering procedure (with 3D displacements < 5 mm) only for the markers placed close to the skin landmarks used for laser alignment. On the contrary, the markers within the irradiation field but not directly controlled during the repositioning procedure exhibited localization errors > 5 mm; this happened even though the inaccuracies related to patient's breathing movements had been excluded from analysis. Moreover, quantitative assessment of global localization errors confirmed the high influence of breathing movements on the position repeatability and maintenance. In this case, even the markers which were on average well repositioned turned out to be significantly displaced during the radiation dose delivery. CONCLUSIONS: Our results confirm that real-time motion analysis based on opto-electronic techniques can play a crucial role as a means of improving patient positioning and assessing immobility. Thus, the system permits to quantify errors in target volume localization, which permits to adopt suitable countermeasures to reduce uncertainties during actual irradiation. This is a crucial requirement, particularly when the complexity of the irradiation geometry (conformal radiotherapy) or radiation type (hadrontherapy) calls for optimal application of the simulated treatment plan to each actual irradiation session.     

Automatic gas exchange control of the autotrophic component in a life support system for heterotrophic organisms

The paper describes an automatic gas exchange control system for the autotrophic component in the life support system of heterotrophic organisms. The paper shows how the automatic control system of the autotrophic component (wheat) can be combined with that of the heterotrophic component (four white rats). The study has demonstrated a high efficiency of the automatic gas exchange control system of plants integrated with animals. The study has also provided balance characteristics of the integrated gas exchange in the plant-animal system.     

The use of liquid latex for detecting traces of blood following thermal exposure

International Journal of Legal Medicine - In cases of crimes involving blood, the perpetrators often attempt to remove the traces they have left behind. Setting fire to the crime scene, aside from...     

Theoretical aspects of developing a system of medical control in space flights]

The paper presents theortical approaches to the medical control system in prolonged space flights. It classifies the most probable states in long-term weightlessness. The main symptoms of these states are described. On the basis of this classification methods and parameters to be used in diagnosis of symptoms that may occur in space flights are discussed.     

Molecular characterization of the canine mitochondrial DNA control region for forensic applications

The canine mitochondrial DNA (mtDNA) control region of 133 dogs living in the area around Innsbruck, Austria was sequenced. A total of 40 polymorphic sites were observed in the first hypervariable segment and 15 in the second, which resulted in the differentiation of 40 distinct haplotypes. We observed five nucleotide positions that were highly polymorphic within different haplogroups, and they represent good candidates for mtDNA screening. We found five point heteroplasmic positions; all located in HVS-I and a polythymine region in HVS-II, the latter often being associated with length heteroplasmy. In contrast to human mtDNA, the canine control region contains a hypervariable 10 nucleotide repeat region, which is located between the two hypervariable regions. In our population sample, we observed eight different repeat types, which we characterized by direct sequencing and fragment length analysis. The discrimination power of the canine mtDNA control region was 0.93, not taking the polymorphic repeat region into consideration. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Experience with gated cardiac software phantoms for quality control of applications programmes

Ten gated cardiac software phantoms, representing normal and abnormal clinical conditions, were transferred to 9 different computer systems and tested with 11 cardiac programmes. Problems of inappropriate data format were encountered when analysing the phantoms on other systems. The global left ventricular ejection fraction (LVEF) values resulting from the different programmes were compared. Significant programme differences were found, the programmes falling generally into two groups. Few LVEF outlier values were identified. Full functional assessment of cardiac phantoms requires a set of different views which together form the phantom. Application of software phantoms for programme assessment and training requires prudence and attention to the acquired data format, frame time, and gating method for the appropriate use of phantoms.     

Experience with gated cardiac software phantoms for quality control of applications programmes

Ten gated cardiac software phantoms, representing normal and abnormal clinical conditions, were transferred to 9 different computer systems and tested with 11 cardiac programmes. Problems of inappropriate data format were encountered when analysing the phantoms on other systems. The global left ventricular ejection fraction (LVEF) values resulting from the different programmes were compared. Significant programme differences were found, the programmes falling generally into two groups. Few LVEF outlier values were identified. Full functional assessment of cardiac phantoms requires a set of different views which together form the phantom. Application of software phantoms for programme assessment and training requires prudence and attention to the acquired data format, frame time, and gating method for the appropriate use of phantoms.     

Automatic continuous monitoring of rectal temperature using a button-type thermo data logger

We performed automatic continuous monitoring of rectal and ambient temperatures using button-type thermo data loggers in autopsy cases. The button-type data loggers have a battery-powered memory that can record 2048 temperature readings. The measurement intervals and other initial settings are determined by computer software, and the measurements were taken at 5-min intervals for this study. At autopsy, the data loggers were retrieved and recorded temperature graphs were produced. This study obtained three representative cases. In one case, the button-type data logger was not discharged regardless of how the body was moved after the device was inserted into the rectum. In two other cases, the cooling curves of the rectal temperature readings clearly followed changes in ambient cooling conditions. The advantages of the tested devices are their small size (diameter, 17.4 mm; thickness, 5.9 mm) and ease of insertion into the rectum, requiring no special skills. Many temperature-based algorithms to determine time of death have been developed, and as a matter of course, the temperature values must be accurate and reliable. Ensuring the validity of each temperature reading requires continuous data from an internal data logger. A button-type data logger is ideal for this purpose.     

Feasibility of using hyperosmolar mannitol as a liquid tumor embolization agent

BACKGROUND AND PURPOSE: This study assesses the cytotoxicity of hyperosmolar mannitol on human endothelial and meningioma cells in vitro and summarizes the initial clinical experience of using mannitol as a liquid tumor embolization agent. METHODS: Human umbilical vein endothelial cells and primary meningioma cells from surgical specimens were treated with 300, 600, 900, and 1200 mOsm of mannitol, mannitol and iohexol mixture, saline, and iohexol alone. Cell death was evaluated with a Live/Dead kit and quantified with thymidine incorporation. From 1998 to 2004, 23 patients with meningioma were treated with mannitol and 31 patients were treated with polyvinyl alcohol (PVA) particles alone. Angiographic results, procedural complications, intraoperative observation, and estimated blood loss during surgical resection were retrospectively evaluated. RESULTS: Minimal endothelial cell death was seen after incubation with 300 mOsm of mannitol for 15 minutes, but 43 +/- 2% of endothelial cells were damaged by 1200 mOsm of mannitol after 30 minutes. Five meningioma cell lines exhibited significant cell death (22 +/- 2%; P < .05) after incubation with mannitol. Satisfactory angiographic results were obtained in all 23 patients. Tumor necrosis was observed intraoperatively and confirmed pathologically. There was no significant difference in estimated blood loss between mannitol- and PVA-embolized patients (407 +/- 64 mL vs 381 +/- 50 mL; P > .75). CONCLUSION: High concentration of mannitol can injure endothelial cells and meningioma cells in a short period of time. It is feasible to use mannitol as a liquid embolic agent to treat meningioma.