Chapters authored
Acute and Chronic Effects of Hypobaric Exposure upon the Brain
Exposure to the hypobaric environment presents numerous physiological challenges to both aviators/pilots, mountain climbers and astronauts. Decompression sickness (DCS) is one of the most commonly experienced maladies and may present variably in protean fashion from mild symptoms such as the bends to severe neurological or pulmonary (i.e. chokes) symptomatology. Furthermore, exposure to extreme non-hypoxic hypobaric environments such as those experienced by our U-2 pilots, irrespective of clinical history of decompression sickness, incites development of white matter hyperintensity lesions that are diffuse in nature. Additionally, non-hypoxic hypobaric exposure also impacts white matter integrity independent of presence of white matter hyperintensities as measured by fractional anisotropy. Functionally, this translated into subtle but significantly lower neurocognitive test performance in U-2 pilots exposed to extreme non-hypoxic hypobaric conditions when compared to pilots without repeated exposure and correlated with degree of white matter lesion burden. In this chapter, we discuss results of our U-2 pilot studies along with published research on high-altitude climbers. We also review ongoing and future directional research and discuss operational implications due to our findings of non-hypoxic hypobaric exposure. Lastly, we examine the incidence of DCS in our astronaut population as well as the risks of performing extravehicular activity (EVA).
Part of the book: Into Space