Simultaneous Determination of Blood Pressure by Oscillometry and Photoplethysmography Compared to the Standard Inert Gas Rebreathing Technique

Rebreathings will be performed every parabola (2, 4, 6, 8, 10…). Ultrasound measurements will be performed during the remaining parabolas (1, 3, 5, 7, 9…). The procedure consists of a fixed breathing frequency of 20 breaths per minute and an exact triggered start point for the measurements. . Central blood pressure measurements, finger blood pressure measurements, impedance cardiography, carotid plethysmography and phonocardiography will be performed continuously during the flights. The breaks between parabolas 10 and 11 and 20 and 21 will be used to change subjects, which takes approximately 5 minutes.