| Lung trauma by rapid decompression is one of serious threatens to flight personnel in aviation activities in high altitude. Scholars home and abroad have studied it at large, clarified its mechanism to a certain extent, established physiological tolerance limit of lung and brought forward protection measures for flight personnel. However , as a result of the change of the cabin pressure system, the fatalness of lung trauma by rapid decompression will increase. At the same time, the technology of study and examination on lung trauma has developed rapidly. So, it is necessary in the aeromedicine field to study further the pathology of lung trauma, emend the criterion of lung physiological tolerance limit to rapid decompression and brought forward more efficacious protection measures.For rapid decompression may do harm to volunteers, it is a usual way for researchers to experiment by animal models and study lung trauma by rapid decompression and protection. In our study, the animal model was established, the changes of rabbits' lung on gross, microstructure and ultrastructure level, and the changes of chemical markers in bronchoalceolar lavage fluid (BALF) and blood of the rabbits wereobserved. In addition, the effects of protective counterpressure on body surface were discussed.38 New Zealand White rabbits (provided by Animal Center in National Institute of the Control for Pharmaceutical and Biologic Products) were devided randomly into 7 groups: the ground control group(n=2), the slow decompression group(n=6), the rapid decompression group of peak value 7.52 kPa(n=6), the rapid decompression group of peak value 9.77 kPa (n=6), the rapid decompression group of peak value 11.89 kPa(n=6), the rapid decompression group of peak value 13.62 kPa(n=6), and the rapid decompression protection group of peak value 13.07 kPa(n=6). They were decompressed from 5 100 m to 12 000 m in the different speeds in the rapid decompression cabin. The 4 rabbits that died and the 23 survivors that were sacrificed were autopsied within 30 minutes postmortem. Their lungs were examined grossly and the sections of lungs were taken for microscopic and electron microscopic examinations. LDH, AKP, UPRO, ACE in BALF and blood were mensurated in all cases.The main results and findings of the study are as following:1. The Animal Model of Lung Trauma by Rapid Decompression in Different Peak ValuesIn our study, the animal lung trauma model in different peak values was established by the way of altering the airways of animal when they were decompressed rapidly. The peak values in the animal model ( 7.52, 9.77, 11.89 and 13.35 kPa) were compared with the expected peak values ( 7.84, 9.80,11.76 and 13.72 kPa), and the error was less than 5 %. So, the animal model is successful and credible.2. Injury on Rabbits' Lung by Rapid Decompression in Different Peak ValuesWe observed the changes of the lung tissue and studied injury on the rabbits' lung by rapid decompression in different peak values by means of gross, microscopic and electron microscopic examinations in our experiment. The results indicate that the slow decompression does not bringabout obvious lung trauma, but the different severity of lung injury occurs under rapid decompression. The greater the decompression peak value is, the more severe lung traumas are caused. Gross examinations of the lungs reveal pulmonary congestion, edema, hemorrhages, congestive or/and hemorrhagic marks on lung surfaces and even alveoli rupture. The microscopic examinations of the lungs show several pathological changes, which are the alveolar canal and the alveolar bursa rupture, the alveolar cavity full of red blood cells and transudatory macrophage, the alveolar septa widened, the alveolar septa engorgement/ haemorrhage and edema, shredding of the alveolar septa, collapse and consolidation of pulmonary system, et al. Rapid decompression can also cause the electron microscopic pathologic changes, such as destroyed alveolar cell(I, II) membrane structure, loose cell connection, edematous... |
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