This review presents lower body negative pressure (LBNP) as a unique tool to investigate
the physiology of integrated systemic compensatory responses to altered hemodynamic …

Humans are generally in standing or sitting positions on Earth during the day. The
musculoskeletal system supports these positions and also allows motion. Gravity acting in …

Importance Exposure to a weightless environment during spaceflight results in a chronic
headward blood and tissue fluid shift compared with the upright posture on Earth, with …

Multiple transitions between gravity levels will occur during planetary exploration missions.
In reaction to these gravitational transitions, physiological adaptation will be initiated …

BACKGROUND: In healthy volunteers, we investigated the ability of the pulse oximeter–
derived peripheral perfusion index (PPI) to detect progressive reductions in central blood …

Our aim was to quantify the end-tidal-to-arterial gas gradients for O2 (PET-PaO2) and CO2
(Pa-PETCO2) during a CO2 reactivity test to determine their influence on the …

BACKGROUND: More than half of astronauts develop ophthalmic changes during long-
duration spaceflight consistent with an abnormal intraocular and intracranial pressure (IOP …

Cardiovascular regulation is integral to life. Animal studies have identified both neural and
endocrine pathways, by which the central nervous system adjusts cardiac output and …

Introduction Lower body negative pressure (LBNP) eliminates the impact of weight-bearing
muscles on venous return, as well as the vestibular component of cardiovascular and …

Purpose To test the hypothesis that the sensitivity of near-infrared spectroscopy (NIRS) in
reflecting the degree of (compensated) hypovolemia would be affected by the application …