Relevance. Diving equipment and diving launch techniques witness continuous improvements, which allow individuals to more effectively perform various tasks underwater. A controlled electronic closed circuit rebreather has been used in amateur diving in our country for more than 20 years. It is therefore necessary to assess the biochemical effects in deep-sea divers wearing deep sea diving equipment to ensure its safety and functionality in professional diving and the activities of dedicated departmental structures.The objective is to assess the biochemical effects in deep-sea divers in controlled electronic closed circuit rebreather, with a similar level of intravascular decompression gas formation under the influence of aquatic environment factors.Methods. During the study, 9 blood biochemical parameters were evaluated using the Fujifilm DRI-CHEM NX500 apparatus in 6 divers before and after deep-sea descents. In total, 14 diving descents were performed in a controlled electronic closed circuit rebreather to depths from 60 to 100 m. Also, after each diving descent, the level of intravascular decompression gas formation was assessed using ultrasonic location with the constant-wave Doppler effect.Results and Discussion. As a result of these studies, a significant increase in the values of transaminases (ALT, AST) and urea was established, associated with increased partial pressure of oxygen in hyperbaric aquatic environment. The results of the analysis revealed that indicators of the CNS oxygen intoxication correlated with K+ ions concentration and glucose levels; a correlation between Na+ ions and Cl- ions concentration was established, as well as the inverse relationship between the concentration of urea and creatinine and the level of intravascular decompression gas formation. It is noteworthy that a correlation was found between the level of intravascular decompression gas formation and the CNS oxygen intoxication, whereby an increase in the CNS oxygen intoxication leads to increased levels of intravascular decompression gas formation.Conclusion. The studied blood biochemical parameters did not go beyond the reference values and had slight individual variations, which confirms the safety of the technology of descents in diving breathing apparatus with a controlled electronic closed circuit rebreather at depths of more than 60 m. The results of the correlation analysis revealed changes in carbohydrate and water-electrolyte metabolism in the body of divers after a deep-sea descent due to the action of an increased partial pressure of oxygen and intravascular decompression gas formation.

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Aim of the work: to identify changes in renal function under the action of dosed hyperoxia using oral stress renal tests and to determine the relationship between the state of the functions of the excretory system and the body’s resistance to toxic effects of oxygen.Materials and methods. A survey of 44 men was carried out. Changes in water-electrolyte metabolism and renal function were determined using developed oral renal stress tests. Results and discussion. It has been shown that the normal functioning of the excretory system plays an important role in the high human resistance to the toxic effects of oxygen.

INTRODUCTION: The relevance of this issue is due to the fact that nowadays there is no common understanding of the influence degree of high partial oxygen pressures on a body functions’ state, depending on individual resistance.OBJECTIVE: Research the state of the functions of the central nervous, cardiovascular and respiratory systems among people with different resistance to the toxic oxygen effect in the descending and the nearest post-descending period.MATERIALS AND METHODS: There was an examination of 11 divers aged 23 to 43 (the average age is 35.5±6.5 years) in conditions of a simulated descent in a pressure chamber to the depth of 15 m (0.25 MPa) while breathing oxygen, and also during 3 days after its termination. Statistic: Software SPSS, v. 20.0 (IBM) was applied for statistical processing of the results.RESULTS: Baseline heart rate (HR) in the low toxic oxygen resistant group (group I) is 10% (р<0.05) higher than the subjects, recognized as resistant (group II). To 60 minutes oxygen breathing (pO2=0.25 MPa) there is a decrease in heart rate (HR) by 12.5% in group I and 11% in group II, comparing the baseline (р><0.05). An increase of diastolic pressure level in group II is 10.5% to 15 min descent and 18% to 45 min, comparing the baseline (р><0.05). In group I the pulse pressure level reduced by 18%, comparing the baseline (р><0.05). Gencha test results after descent rose by 55% in group I and by 62.5% in group II, comparing the baseline (р�0.05), and indicators higher than initial remained for 3 days more. In group I there was reduction of information processing speed by a visual analyzer of 16% (from 0.788 to 0.661 b/sec) and increase in escape latency of a simple visual-motor reaction by 11.7%, comparing the baseline (р><0.05). DISCUSSION: Divers with different resistance to the toxic oxygen effect experience multidirectional reaction of the central nervous, cardiovascular and respiratory systems. Individuals, resistant to the toxic oxygen effect, are characterized by more active inclusion of counteraction mechanisms to hyperoxia and significant reduction in the level of adaptation reserves and the efficiency of the cardiovascular system. People with low resistance experience a decrease in the functionality level of the central nervous system. CONCLUSION: The results obtained have a basis for admitting the application of the method of determining individual body resistance to the toxic oxygen effect and tests with increasing dosed physical activity in order to estimate adaptation reserves and efficiency. >< 0.05) higher than the subjects, recognized as resistant (group II). To 60 minutes oxygen breathing (pO2=0.25 MPa) there is a decrease in heart rate (HR) by 12.5% in group I and 11% in group II, comparing the baseline (р< 0.05). An increase of diastolic pressure level in group II is 10.5% to 15 min descent and 18% to 45 min, comparing the baseline (р< 0.05). In group I the pulse pressure level reduced by 18%, comparing the baseline (р< 0.05). Gencha test results after descent rose by 55% in group I and by 62.5% in group II, comparing the baseline (р 0.05), and indicators higher than initial remained for 3 days more. In group I there was reduction of information processing speed by a visual analyzer of 16% (from 0.788 to 0.661 b/sec) and increase in escape latency of a simple visual-motor reaction by 11.7%, comparing the baseline (р< 0.05).DISCUSSION: Divers with different resistance to the toxic oxygen effect experience multidirectional reaction of the central nervous, cardiovascular and respiratory systems. Individuals, resistant to the toxic oxygen effect, are characterized by more active inclusion of counteraction mechanisms to hyperoxia and significant reduction in the level of adaptation reserves and the efficiency of the cardiovascular system. People with low resistance experience a decrease in the functionality level of the central nervous system.CONCLUSION: The results obtained have a basis for admitting the application of the method of determining individual body resistance to the toxic oxygen effect and tests with increasing dosed physical activity in order to estimate adaptation reserves and efficiency.