The arterial baroreflex and inherent G tolerance.

Purpose: High G tolerance is based on the capacity to maintain a sufficient level of arterial pressure (AP) during G load; therefore, we hypothesized that subjects with high G tolerance (H group) would have stronger arterial baroreflex responses compared to subjects with low G tolerance (L group). The carotid baroreflex was evaluated using the neck pressure method (NP), which assesses open-loop responses.

Methods: The carotid baroreflex was tested in 16 subjects, n = 8 in the H and L group, respectively, in the supine and upright posture.

Dysfunctional vestibular system causes a blood pressure drop in astronauts returning from space.

It is a challenge for the human body to maintain stable blood pressure while standing. The body's failure to do so can lead to dizziness or even fainting. For decades it has been postulated that the vestibular organ can prevent a drop in pressure during a position change--supposedly mediated by reflexes to the cardiovascular system.

Three dimensional Ballistocardiogram and Seismocardiogram: what do they have in common?

3D-body accelerations, i.e. Ballistocardiograms (BCG) and Seismocardiograms (SCG), ECG and Impedance-cardiograms (ICG) were recorded on healthy volunteers participating to the European Space Agency (ESA) 59th parabolic flight campaign.

Perception of verticality and cardiovascular responses during short-radius centrifugation.

Background: Artificial gravity using short-radius centrifugation has been proposed as an integrative countermeasure during spaceflight.

Objective: To determine the rotation parameters of a short-radius centrifuge so that subjects rotating in the dark would feel as if they were standing upright.

Methods: Twelve subjects were lying supine in a nacelle on a 2.

Timing and source of the maximum of the transthoracic impedance cardiogram (dZ/dt) in relation to the H-I-J complex of the longitudinal ballistocardiogram under gravity and microgravity conditions.

The transthoracic impedance cardiogram (ICG) and the acceleration ballistocardiogram (BCG) measured close to the center of mass of the human body are generated by changes of blood distribution. The transthoracic ICG is an integrated signal covering the whole thorax and spatial resolution is poor. Comparison between both signals can be used to elucidate the source of the ICG signal.