Circulating blood volume is reduced during spaceflight, making astronauts hemodynamically compromised. After landing, astronauts separate into two groups. One group compensates for the hypovolemia with a hyper-sympathetic response during upright tilt testing and can complete a tilt test with few symptoms. The other group is unable to mount a hyper-sympathetic response and experiences orthostati...

2011 urban Canadians. The physician must adapt to these differences and avoid imposing his own perspective. The same is true on orbit, with crews generally of international composition. Risk management Living in a remote area is a health risk in itself: for example, the chances of surviving a major head trauma are several orders of magnitude lower when the nearest neurosurgeon and ICU are sever...

We read with interest and enthusiasm the recent article by Sibony and colleagues which accurately described the biomechanical etiology of peripapillary wrinkles, retinal folds, and choroidal folds caused by idiopathic intracranial hypertension (IIH). The authors correctly state that chorioretinal folds have been documented in a variety of ophthalmic disorders including the microgravity environm...

INTRODUCTION Orthostatic hypotension and presyncope are common and potentially serious risks for astronauts returning from space. Susceptible subjects fail to generate an adequate adrenergic response to upright posture. The alpha-1 adrenergic agonist, midodrine, may be an effective countermeasure. We tested the hypothesis that midodrine would have no negative hemodynamic effect on healthy astro...

Forthcoming human planetary exploration will require increased scientific return (both in real time and post-mission), longer surface stays, greater geographical coverage, longer and more frequent EVAs, and more operational complexities than during the Apollo missions. As such, there is a need to shift the nature of astronauts’ scientific capabilities to something akin to an experienced terrest...

Cardiovascular adaptations driven by exposure to weightlessness cause some astronauts to experience orthostatic intolerance upon return to Earth. Maladaptations of spaceflight that lead to hemodynamic instability are temporary, and therefore astronauts provide for researchers a powerful model to study cardiovascular dysfunction in terrestrial patients. Orthostatic intolerance in astronauts is l...

BACKGROUND It is unknown whether the astronaut occupation or exposure to microgravity influences the risk of long-term cardiovascular disease (CVD). This study explored the effects of being a career National Aeronautics and Space Administration (NASA) astronaut on the risk for clinical CVD end points. METHODS AND RESULTS During the Longitudinal Study of Astronaut Health, data were collected o...