We studied clinical manifestations and outcomes in nine patients with acute carbon monoxide （CO） poisoning caused by indoor use of electric generators during the Boso Peninsula Typhoon that made landfall near Chiba City in 2019. To prevent delayed neuropsychiatric sequelae （DNS）, we recommend hyperbaric oxygen therapy （HBO） based on loss of consciousness, neurological symptoms, myocardial damage, acidosis, exposure time, age, and the estimated blood CO hemoglobin concentration at the time of patient rescue. The initial HBO protocol was 90 minutes （30 minutes of oxygen, three times） at 2.8 ATA for all patients. In addition, if patients had presence of 1） loss of consciousness, 2） an exposure time of 6 hours or more, or 12 hours or more from the start of exposure, or 3） myocardial damage, additional HBO treatments were conducted. No patients developed DNS. Patient selection criteria and treatment methods for acute CO poisoning need to be revised as time goes on, with a focus on DNS prevention and repeated evaluations of cases.

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［Background］Streptococcus pneumoniae is the most common cause of pneumonia and is also an important cause of sepsis and other diseases with high mortality rates. In recent years, the emergence of resistant bacteria has become a medical problem, and new treatment methods are required. Hyperbaric oxygen therapy （HBO） is effective against some bacterial infections, but reports of HBO effects on the clinically important Streptococcus pneumoniae are few.
［Purpose］This study aimed to determine the effects of the HBO environment on the growth of Streptococcus pneumoniae in vitro.
［Materials and methods］Five strains of Streptococcus pneumoniae （SP） were obtained from American Type Culture Collection （ATCC） in this study. HBO was performed using experimental Equipment （P-5100, Barotec Hanyuda） at 2.4 ATA in 100％O₂ for 1 hour, which was defined as experimental HBO （eHBO）. SP was seeded in the Sheep Blood Ager medium and treated by eHBO. After eHBO treatment, the culture dishes were incubated in 5％CO₂ at 36℃ for approximately 20 hours. After the incubation, the numbers of colonies and the colony sizes were measured.
［Results］In five strains of SP, the numbers of colonies were not suppressed but the sizes of colonies were suppressed due to eHBO treatment. Particularly, the unit area of colonies of #10813 and #49619 strains of SP significantly （P＜0.05） decreased 33.1％and 21.6％compared to the control, respectively. In addition, eHBO clearly suppressed the unit area of colonies of the #10813 strain in the growth phase of SP, suggesting that the HBO should be effective even during the progress of infection.
［Conclusion］This study indicates that the HBO environment slows down the growth of Streptococcus pneumoniae in vitro.

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Background: Saturation diving （SD） is a useful diving technique for safe deep-sea operations such as salvage or submarine rescue. As a breathing gas, heliox is considered less likely to cause gas narcosis during SD. There have been few studies on diver muscular performance under hyperbaric conditions such as SD. Therefore, we evaluated diver muscular exertion abilities to develop maximal force （MAX） and stabilize constant force （CONST）, as well as brain activities in CONST during 45 atmosphere absolute （ATA） Heliox SD.
Methods: Participants included ten male saturation divers from the Japan Maritime Self-Defense Force （JMSDF） （age; 35.8±5.1［SD］ years） who had completed 45ATA Heliox SD （dry） training and had undergone two handgrip exercise tests: The maximum force （MAX） development and the coefficient of variance in the grip strength （20％ of the maximum force） （CONST） at 1ATA and 45ATA. MAX evaluated the maximum force development of the right hand. CONST evaluated the coefficient of variance （CV） in grip strength while monitoring real-time force. In terms of brain activity, we examined electroenphalograms in CONST and calculated brain current densities using standardized low resolution electromagnetic tomography （sLORETA）.
Results: MAX maximum grip strength at 45ATA （26.7±7.2kg） was significantly lower than at 1ATA （31.6±8.6kg）. CONST CV at 45ATA （8.7±4.4％） was significantly higher than at 1ATA （4.8±2.0％）. There were no differences in brain current densities between 1ATA and 45ATA in sLORETA.
Conclusion: Our results showed that the muscular abilities to develop maximal force and stabilize force were impaired during 45ATA deep heliox SD. However, we did not find any differences in brain current densities for 1ATA and 45ATA, which suggests that deep SD impairs muscular exertion abilities and interferes with diving operations.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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