Study Of Preoxygenation Program On Fast Ascent After Rabbits Been Exposed To Hyperbaria

Fast ascent is the most advanced submarine crew escape single technology when submariners not been exposured to high-pressure situation, which is the most advanced single-man escape technology has been widely adopted around the world. And it will become one of the conventional escape methods of Chinese Navy. But in the Specific implementation of fast ascent drift out of danger, in order to avoid decompression sickness, there need to maintain the atmospheric conditions of submarine compartments as a precondition, which is an obvious technical flaw of fast ascent, this shortcoming has become the biggest obstacle of fast ascent in the practical application encountered.The working based on the classical oxygen desaturation safety principles of inert gas, preoxygenation solution for the submarine escape restrictions. First with the basic experimental study in rabbits, according to the different depth of the submarine accidents, and high pressure conditions of exposure duration, select different oxygen inhaled escape plans; Evaluat the effects of oxygen inhaled to prevent decompression sickness after rapid decompression. To ensure the safety and practicality of haperbaric oxygen, through the behavior, EEG and cerebral blood flow evaluation and prediction of observed incidence of oxygen toxicity. And eveluate preoxygenation program prevents decompression sickness after rapid decompression on the mechanism. According to the experimental results for the latter part of the program, with large animals (goats) repeat the above experiments, and based on animal experimental data, give the depth of proposed human exposure research program under the conditions of the specific program recommendations.The working confirms the use of preoxygenation measures, fast asent after animals'exporsured in high-pressure the feasibility and exposure in and propose a different under conditions of hyperbaric oxygen exposure to the program. The study will improving submarine rescue capability and enhancing our country in the field of international academic standing of great significance.According to above, we carried out the following studies:1) Filter out fast ascent programs According to the different circumstances of the submarine accidents, develop different oxygen inhale programs. Through observation of decompression sickness in animals, choose the best solution for animal oxygen inhaled fast asent.2) Evaluation of preoxygenation treatment to prevent decompression sickness after rapid decompression.Evaluated oxygen inhaled fast ascent plan and the relationship between the incidence of decompression sickness in rabbits and the severity of decompression sickness.Observed indicators: performance of animal behavior, indicators of lung pathology in general, cardiovascular bubble, tissue biopsy and so on.3) Safety Evaluation of preoxygenation treatmentTo ensure the safety and practicality of preoxygenation treatment, through the behavior, EEG and cerebral blood flow of rabbits to observe the occurrence of oxygen toxicity and evaluate the forecasts, the behavior, pathological changes of lung oxygen toxicity index as an evaluation.4) The mechanism study of preoxygenation treatment to prevent decompression sickness after rapid decompression.By Western Blot method, real-time quantitative PCR, DNA binding activity ELISA assays preoxygenation programs on rabbits'spinal cord HIF-1 and HSF-1 transcriptional activity and its downstream target genes EPO and HSP70 changes.The main results are as follow:1) Fast ascent program developing According to the different circumstances of the submarine accident, develop different oxygen inhaled escape programs. By observing the incidence of decompression sickness, selected the hyperbaric oxygen treatment programs prevention of decompression sickness.2) Evaluation of preoxygenation programs prevents decompression sickness after rapid decompression.Study the relationship between preoxygenation programs and the incidence and the severities of decompression sickness in rabbits.In escape planⅣ:30 m saturated-60 m 10 min, under high pressure and oxygen inhaled 2 h(200 kPa,60 min×2;300 kPa,30 min×4) could significantly reduce the incidence of decompression sickness and severity, and inhaled oxygen 30 min to prevent decompression sickness has been a marked effect occurred. Oxygen treatment can significantly reduce the incidence of decompression sickness, and reduce the extent of the damage various organs. Oxygen-induced convulsion does not appeard throughout the whole process.3) Safety Evaluation of preoxygenation programs (1) According to the oxygen needs of safety and practicality, the project intends to two ways:Animals exposured to 250 kPa or less pressure inhaled pure oxygen 1 h, air suction interval of 10 min, then continuous suction pure oxygen 1 h. A total of pure oxygen absorption 2 h;Animals exposured to 250 kPa or more pressure of oxygen exposured 30 min, air suction interval 10 min, then continuous suction of pure oxygen 30 min. Repeat 4 times, a total of pure oxygen absorption 2 h;After filtering, 200 kPa (60 min×2) and 300 kPa (30 min×4) preoxygenation programs were selected. The pathological changes in the lung: pulmonary capillary strategic expansion, congestion, bronchial epithelium deformation, and pulmonary quality of a small amount of red blood cells and alveolar cavity exudates and inflammatory cell infiltration. Preoxygenation can cause the protein content of bronchoalveolar lavage fluid and total cell number increased, No oxygen convulsion animal performanced throughout the HBO programs.(2) EEG measured under high pressure is used to determine whether the occurrence of acute oxygen toxicity. According to previous studies, when oxygen partial pressure is lower than 250 kPa, the central nervous system acute oxygen toxicity is unlikely. When oxygen partial pressure is more than 250 kPa,there with the possibility of the central nervous system acute oxygen toxicity. At 200 kPa (60 min×2) and 300 kPa (30 min×4) preoxygenation programs the whole process does not appear paroxysmal long, high-volatility multi-spike; only seen the occasional post-exposure single negative phase Spike or sharp wave of abnormal discharge.(3) The establishment of cerebral blood flow measurement techniques, prediction of acute oxygen poisoning attack. Records showed that cerebral blood flow, preoxygenation group (HBO1, HBO2) animals in a relatively stable state, without significantly increased and reduced, and no significant difference with hyperbaric air control group. 4) To study the molecular mechanism of preoxygenation treatment prevention of decompression sickness in rabbits, experimental subjects observed the preoxygenation programs on rabbit spinal cord HIF-1 and HSF-1 transcriptional activity and preoxygenation programs on the rabbit spinal cord of oxygen HIF-1 and HSF-1 downstream target genes. The results showed that:(1) Preoxygenation treatment can significantly increase rabbit spinal cord tissue HIF-1αand HSF-1 nuclear protein content.(2) Preoxygenation treatment can significantly increase rabbit spinal cord EPO (HIF-1 target gene) and HSP70 (HSF-1 target gene) protein content.