Objective To observe pre-syncopal limited tolerance and cardiovascular responses to head-up tilt combined with lower body negative pressure (HUT/LBNP) following exposure to head-down tilt (HDT, -1 Gz). Method Exposures to HUT/LBNP (-60 mmHg) in control session (without preceding 30 s -1 Gz treatment) and in simulated push-pull effect (PPE) session (with preceding 30 s -1 Gz treatment) were performed in 8 healthy adults. The changes of hemodynamic parameters were monitored by electrical impedance instrument during the experiments. Result The mean endurance time in presyncopal symptom limited HUT/LBNP in control session and in simulated PPE session were 8.4±2.1 min and 4.5±2.4 min, respectively, the two means were significantly different (P< 0.01). In simulated PPE session, as compared with baseline, heart rate (HR) during HDT was significantly lowered (P<0.01), while stroke volume (SV) and cardiac output (CO) were increased significantly (P<0.01). During HUT/LBNP, the increased percentage (relative to baseline) of HR in PPE session was lower than these in control session (P<0.05); the decreased percentages of SV and CO during HUT/LBNP in PPE session were both higher than those in control session (P<0.05). During HUT/LBNP, arterial pulse pressure (PP) of control session was significantly decreased than the value of baseline value (P<0.05); Total peripheral resistance (TPR) of PPE session was significantly increased than baseline value (P<0.05). Conclusion Tolerance time before the appearance of presyncopal symptoms during HUT/LBNP decreases and cardiovascular responses to HUT/LBNP are impaired, preceding exposure to HDT.

The article described the characteristics of research teaching and try to adopt a different research teaching methods based on the characteristics of the contents of each chapter of aerospace biodynamics to enhance the effectiveness of military medicine lesson and cultivate innovative thinking ability of students in military schools.

BACKGROUND: At present, most researches on simulated weightlessness are confined to its effect on the artery. Therefore, the effect on the vein needs to be further studied.OBJECTIVE: To probe into the effect of simulated weightlessness on the ultrastructure of rabbit femoral vein and the remodeling of femoral vein.DESIGN: A completely randomized and controlled trial based on experimental animals.SETTING: Department of Aerospace and Aviation Medical Science, Fourth Military Medical University of Chinese PLA.MATERIALS: The experiment was completed in the Department of Aerospace and Aviation Medical Science, Fourth Military Medical University of Chinese PLA from December 2000 to December 2001. Altogether 24healthy male New Zealand rabbits, weighing 2.0-2.5 kg were obtained.INTERVENTIONS: The model of Head-Down Tilt( -20°) (HDT) simulated weightlessness was established in rabbits. A total of 24 healthy male New Zealand rabbits were randomly divided into control group, 10-day simulated weightlessness group and 21-day simulated weightlessness group, with 8rabbits in each group. The ultrastructure of the rabbit femoral vein was observed under transmission electron microscope.MAIN OUTCOME MEASURES: Changes and degeneration of endothelial cell, mitochondrion, internal elastic membrane, and smooth muscle.RESULTS: Cell organelles in endothelial cell of the femoral vein of HDT rabbits decreased, mitochondrion dissolved and disappeared, vacuolar degeneration in endothelial cell increased and phagolysosome in endothelial cell could be found. Internal elastic membrane became thinner and was broken. The smooth muscle layer became thinner and some smooth muscle cells became degenerated. Cell interstitial substance increased. There was significant difference in changes between 21-day and 10-day simulated weightlessness groups.CONCLUSION: The vascular remodeling of femoral vein occurs with atrophic changes during simulated weightlessness. The longer duration of simulated weightlessness is, the more obviously the structure of femoral vein changes.

This paper reviews the etiology , pathogenesis ,prediction and evaluation and other related aspects of motion sickness in order to contribute to further research on motion sickness and to proride the theorotic basis for prevention .

Objective:To explore the relevance of a new comprehensive respiratory mechanics parameter, elastic power, to the 28-day prognosis of ARDS patients.Methods:Patients with ARDS hospitalized for at least 48 h with invasive mechanical ventilation in five intensive care units in three local hospitals in Lianyungang City from June 2018 to June 2022 were included in the study. Their baseline data and respiratory mechanics parameters were collected. Elastic power, mechanical power, driving pressure and lung compliance are calculated according to the corresponding formulae. The prognostic risk factors of ARDS patients were analysed using COX multi-factor regression, and the predictive value of EP/Cst on the 28-day prognosis of ARDS patients was evaluated based on ROC curve analysis and Kaplan-Meier survival curve.Results:There was no significantly difference in tidal volume and PEEP settings between the patients in the ARDS survivor and death groups ( P> 0.05). However, the differences in respiratory rate, plateau pressure, driving pressure, lung compliance, mechanical work, elastic work, EP/cst and MP/cst between the two groups were significantly different (all P< 0.01). Multifactorial COX regression analysis showed that EP/cst ( HR=1.211, 95% CI:1.091-1.323) and RR ( HR=1.209, 95% CI:1.046-1.339) were strongly associated with a more severe degree of illness and a worse prognosis in ARDS. And the cumulative survival rate at 28 d was significantly lower in the high Cst-EP group than in the low Cst-EP group (50.00% vs. 82.40%, P < 0.01). Conclusions:The new respiratory mechanics parameters EP and EP/Cst can assess the severity of ARDS with a good predictive effect on patient prognosis at 28 days.

Objective:To construct a reliability management model of medical equipment in the department of respiratory and critical care medicine,and to explore its application effect in the management of medical equipment in the department of respiratory and critical care medicine.Methods:Taking the reliability of equipment management content and management methods as evaluation indexes,standardized procedures of equipment use,cleaning and emergency management were formed,and a reliability management model for medical equipment in the department of respiratory and critical care medicine was constructed.A total of 63 medical devices in clinical use in the Department of Respiratory and Critical Care Medicine of Beijing Anzhen Hospital,Capital Medical University from January 2022 to January 2023 were selected.According to different management modes,conventional management mode(32 devices)and reliability management mode(31 devices)were adopted respectively.The equipment management index score,equipment goal achievement degree and equipment management defect rate,and the equipment management recognition scores of the engineers,equipment operation technicians and doctors of equipment use management were compared between the two management modes.Results:The average recognition scores of the engineers,operating technicians and doctors for the use of equipment of the reliability management model were(90.66±5.25)points,(91.54±4.14)points and(92.17±5.17)points,respectively,which were higher than those of the conventional management model,the difference was statistically significant(t=14.249,13.773,12.267,P<0.05).The average scores of equipment resource allocation,information technology,technical support and management performance indicators of the reliability management mode were(90.25±4.12)points,(92.45±3.26)points,(91.47±2.78)points and(90.25±3.11)points,respectively,which were higher than those of conventional management mode,the difference was statistically significant(t=12.122,18.379,15.581,14.141,P<0.05).The average scores of equipment use standardization,cleaning completion and emergency management timeliness of reliability management mode were(92.36±3.25)points,(90.69±3.69)points and(91.87±3.01)points,respectively,which were higher than those of the conventional management mode,the difference was statistically significant(t=14.953,15.030,14.401,P<0.05).The number of equipment damaged,repaired and factory repair of the reliability management mode was 1,1 and 2,respectively,and the defect rates were 3.22%,3.22%and 6.45%,respectively,which were lower than those of the conventional management mode,the difference was statistically significant(x2=8.581,9.908,8.782,P<0.05).Conclusion:The application of reliability-based medical equipment management model to the medical equipment management of respiratory and critical care medicine can improve the quality of equipment management and operation,reduce the failure rate of equipment,and improve the service level of equipment.