Aviat Space Envir Md
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The goal of this study was to investigate the contribution of splanchnic volume redistribution and lower limb vasoconstriction in the maintenance of blood pressure during progressive central hypovolemia induced by graded lower body negative pressure (LBNP). It was hypothesized that splanchnic blood volume loss during LBNP would buffer decreases in thoracic blood volume. ⋯ Our results suggest that splanchnic blood volume redistribution--rather than leg vasoconstriction--plays an important role in blood pressure regulation during central hypovolemia.
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Hypobaric hypoxia during commercial air travel has the potential to cause or worsen hypoxemia in individuals with pre-existing cardiopulmonary compromise. Knowledge of cabin altitude pressures aboard contemporary flights is essential to counseling patients accurately about flying safety. The objective of the study was to measure peak cabin altitudes during U.S. domestic commercial flights on a variety of aircraft. ⋯ Peak cabin altitude on commercial aircraft flights has risen over time. Cabin altitude is lower with flights of shorter distance. Physicians should take these factors into account when determining an individual's need for supplemental oxygen during commercial air travel.
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Aviat Space Envir Md · Nov 2012
ReviewAcute neurological symptoms during hypobaric exposure: consider cerebral air embolism.
Cerebral arterial gas embolism (CAGE) is well known as a complication of invasive medical procedures and as a risk in diving and submarine escape. In the underwater environment, CAGE is caused by trapped air, which expands and leads to lung vessel rupture when ambient pressure decreases during ascent. Pressure decrease also occurs during hypobaric activities such as flying and, therefore, CAGE may theoretically be a risk in hypobaric exposure. ⋯ We recommend considering CAGE in all patients presenting with acute central neurological injury during or shortly after pressure decrease such as flying. A CT scan of head and chest should be performed in these patients. Treatment with hyperbaric oxygen therapy should be initiated as soon as possible in cases of proven or probable CAGE.
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Aviat Space Envir Md · Nov 2012
Clothing buoyancy and underwater horizontal swim distance after exiting a submersed vehicle simulator.
Winter road workers, who drive heavy vehicles over ice-covered waterways, are at risk for ice failure, vehicle submersion, and subsequent drowning in frigid water. Although some jurisdictions require these workers to wear flotation clothing, there are concerns that, following an underwater exit in fast-moving water, increased clothing buoyancy may reduce ability to swim against the current to safely return to the ice opening. ⋯ Flotation clothing (either Jackets or Overalls) is recommended for vehicle travel on ice because they do not impede underwater exit from a vehicle and allow significant horizontal underwater swim distance. An inflatable vest is not recommended because inappropriate premature inflation could increase exit impedance and decreased underwater swim distance.
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Aviat Space Envir Md · Oct 2012
Commercial spaceflight participant G-force tolerance during centrifuge-simulated suborbital flight.
Medical knowledge of the human body in microgravity and hypergravity is based upon studies of healthy individuals well-conditioned for such environments. Little data exist regarding the effects of spaceflight on untrained commercial passengers. We examined the responses of potential spaceflight participants (SFP) to centrifuge G-force exposure. ⋯ The results suggest that most individuals with well-controlled medical conditions can withstand acceleration forces involved in launch/landing profiles of commercial spaceflight vehicles. Further investigation will help refine which conditions present significant risk during suborbital flight and beyond.