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INTRODUCTION: I nhalation of hydrazine or hydrazine-derivative (for example, monomethylhydrazine) vapors during spaceflight operations remains a risk to crew and ground support personnel. Here we sought to provide an evidence-based approach to inform acute clinical treatment guidelines for inhalational exposures during a noncatastrophic contingency spaceflight recovery scenario. METHODS: A review of published literature was conducted concerning hydrazine/hydrazine-derivative exposure and clinical sequelae. Priority was given to studies that described inhalation though studies of alternative routes of exposure were additionally reviewed. Where possible, human clinical presentations were prioritized over animal studies. RESULTS: Rare human case reports of inhalational exposure and multiple animal studies provide evidence of varied clinical sequelae, including mucosal irritation, respiratory concerns, neurotoxicity, hepatotoxicity, hemotoxicity (including Heinz body development and methemoglobinemia), and longitudinal risks. In an acute timeframe (minutes to hours), clinical sequelae are likely to be limited to mucosal and respiratory risk; neurological, hepatotoxic, and hemotoxic sequelae are unlikely without recurrent, longitudinal, or noninhalational exposure. CONCLUSIONS: Acute clinical management should focus on likely clinical concerns as supported by existing data; recovery medical personnel should be prepared to manage mucosal irritation and respiratory concerns, including the potential need for advanced airway management. There is little evidence supporting the need for acute interventions for neurotoxicity and there is no evidence that acute hemotoxic sequelae would drive the need for on-scene management of methemoglobinemia, Heinz body development, or hemolytic anemia. Training that overemphasizes neurotoxic or hemotoxic sequelae or specific treatments for such conditions potentially raises the risk for inappropriate treatment or operational fixation. [ABSTRACT FROM AUTHOR]

INTRODUCTION: This case report presents a hypothetical lunar decompression sickness (DCS) event with consideration of treatment approach and disposition. BACKGROUND: Lunar extravehicular activities (EVA) pose a risk of developing DCS from operational shifts in pressure between suits and lunar habitats. Although prebreathe protocols theoretically decrease the risk of DCS through denitrogenation, the consequences of an event are mission critical. Type I DCS represents the majority of hypobaric pathology and many medical organizations implement 'return-to-duty' guidelines following treatment. This case will overview a hypothetical occurrence of Type I DCS on a lunar surface EVA in an experienced astronaut and will highlight treatment, return to flying status, and mission impact. CASE PRESENTATION: A 55-year-old female crewmember with extensive EVA experience developed right knee pain during her first lunar surface sortie. The pain severity distracted her from mission objectives and the EVA was aborted by the supervising flight surgeon given suspicion for DCS. The crewmember was treated with an in-suit repressurization protocol and her symptoms resolved. She had no prior history of DCS and subsequent EVA for the following three days were cancelled by flight medicine due to the risk of recurrence and performance decrement. DISCUSSION: Exploration missions will require extensive EVA capabilities for sustained space operations, including the lunar surface and beyond. Although recurrence of treated DCS is plausible, a clear delineation of risk factors makes 'return-to-duty' difficult so mitigation continues to be the best treatment for DCS. Clinical guidelines to minimize post-treatment risk of DCS recurrence exist within the Department of Defense, commercial diving, and recreational diving sectors, however, there is a paucity of literature for cases such as this astronaut treated with hyperbaric pressures utilizing in-suit protocols. This case report will highlight the current mission implications of DCS including unavailability of standard 41.1 psia (2.8 ATA) hyperbaric oxygen, difficulty in medical evacuation from the lunar surface, and approach to returning a crewmember back to mission EVA status. Learning Objectives 1. The audience will gain an appreciation of risk assessment for recurrent decompression sickness in a hypothetical astronaut crewmember on a long-duration lunar surface mission. 2. The audience will learn how existing medical guidelines may apply to return-to-duty assessment for individuals operating in a hypobaric lunar habitat environment and lunar surface EVA. [ABSTRACT FROM AUTHOR]

The mechanism underlying the sperm quality advantage is elucidated through examination of the relationship between female sperm-storage organ morphology and the differential organization of different sperm within the organ in Drosophila melanogaster. It is demonstrated that both sperm quality and sperm quantity independently contribute to competitive male fertilization success and the significant interaction that took place between sperm quality and quantity suggests internal positive reinforcement on selection for sperm quality.