Profound knowledge about cardiovascular physiology in the setting of microgravity can help in the course of preparations for human space missions. So far, influences of microgravity on the cardiovascular system have been demonstrated, particularly pertaining to venous fluid shifts. Yet, little is known about the mechanisms of these adaptations on continuous macrocirculatory level and regarding the microcirculation.
Twelve healthy volunteers were subjected to alternating microgravity and hypergravity in the course of parabolic flight maneuvers. Under these conditions, as well as in normal gravity, the sublingual microcirculation was assessed by intravital sidestream dark field microscopy. Furthermore, hemodynamic parameters such as heart rate, blood pressure, and cardiac output were recorded by beat-to-beat analysis. In these settings, data acquisition was performed in seated and in supine postures.
Systolic [median 116 mmHg (102; 129) interquartile range (IQR) vs. 125 mmHg (109; 136) IQR,
Profound changes of the macrocirculation were found in seated postures, but not in supine postures. However, microcirculation remained stable in all postures.