Information PendingPrincipal Investigator(s)
University of Brussels (ULB-MRC and VUB), Brussels, , Belgium
European Space Agency (ESA)Sponsoring Organization
Information PendingResearch Benefits
Information PendingISS Expedition Duration
June 2002 - December 2002Expeditions Assigned
5Previous ISS Missions
This experiment is based on previous experiments performed in near weightlessness. (Euromir-95: 6 months in space and Neurolab STS-90: 15 days in space). Our results have shown that heart rate (HR) decreases in a weightless environment, shows an adaptation during the flight, increases on return to normal gravity and remains high up to 15 days after return. In addition, it was demonstrated that the analysis of the heart rate variability (HRV), specially its respiratory component, the respiratory sinus arrhythmia (RSA), could bring new understanding to the adaptation of the autonomic control of HR and the cardio-pulmonary system to weightlessness. Our observations, and other published studies, indicate that an adaptation of the autonomic control of HR occurs in near weightlessness and that this adaptation is, at least partially, responsible for the orthostatic intolerance that astronauts endure after exposure to the space environment. As severity of orthostatic intolerance increases with exposure to weightlessness, this could be a potential hazard for longer spaceflight, especially for the accomplishment of a human mission to Mars. Respiratory movements, electrocardiogram, continuous blood pressure (BP) and systolic time intervals will be non-invasively measured. This experiment includes the repetition of 2 controlled tidal breathing (CTB) protocols already performed during STS-90 as well as 3 additional CTB protocols to answer questions raised by previous analysis. The spectral analysis of HRV as well as the amplitude and phase of the RSA will be studied as non-invasive markers of the sympathetic parasympathetic balance of the autonomic control of HR. The RSA depends on breathing frequency. The proposed protocol, imposing multiple controlled breathing frequencies, allows studying different states of the autonomic control. Previous studies (Neurolab study to be submitted) have shown that 15 days after return to normal gravity, cardiac parameters had not yet reached pre-flight values. This experiment, with measurements during week 3 and 4 after landing, should shed light on the cardiorespiratory re-adaptation to normal gravity.In addition to HRV analysis, this proposal includes the measurement of pulse transit time (PTT) and systolic time intervals (Pre Ejection Period (PEP) and Left Ventricular Ejection Time (LVET)), before and after the flight. This allows corroborating alterations of HRV and RSA with independent measurements that will help in the interpretations of alterations of the different autonomic components. Experiments performed during the 29th ESA parabolic flight campaign demonstrated the strong gravity and posture dependence of these parameters, which support the hypothesis that systolic time intervals and PTT are useful non-invasive tools to follow the long-term cardiovascular re-adaptation to normal gravity.The main scientific objectives of the experiment are testing the following hypothesis: In flight, adaptation of autonomic control of HR occurs and is in part responsible of the observed post-flight tachycardia, which persists up to 15 days after landing. The amplitude and phase of the RSA observed during multiple controlled breathing experiments can trace the re-adaptation to normal gravity of the parasympathetic component of autonomic control of HR. PEP, PTT and LVET are markers of the cardiovascular function that can trace the re-adaptation of the autonomic control of HR and BP after spaceflight.
Information PendingEarth Applications
Information PendingOperational Protocols
Experimental data collection begins on-ground at L-90, L-60, L-30 and L-15 days before launch. Each session lasts about 48 minutes and is equally split up with the same procedure being performed in both the standing and supine position. Each session begins with 3 minutes of spontaneous breathing. Thereafter, 5 controlled breathing protocols are executed which consist of 1 minute spontaneous breathing plus calibration of the Portapres plus Doppler measurement, followed by 3 minutes of paced breathing at rates of, respectively, 15, 12, 9, 7.5 and 6 breaths per minute. The Portapres is a finger cuff used to measure finger blood pressure (BP) (Figure 1).The 20-minute in-flight procedure consists in 5 periods of controlled breathing protocol. Each period starts with a period of 1 min breathing at rest, allowing the re-calibration of the Portapres. This period is immediately followed by 3 min breathing at a controlled frequency. This control of breathing is very simple to achieve and requires only minimum training. Control of breathing will be achieved by presenting to the subjects a zigzag curve and/or metronome fluctuations of a vertical bar graph generated by a computer laptop at the desired frequency, cues that he should follow. During this part of the experiment the subject is free to adjust the depth of his breath so as not to hyper or hypo-ventilate. The breathing frequencies that will be recorded (0.1; 0.125; 0.15; 0.2; 0.25 Hz corresponding to 6, 7.5, 9, 12, 15 breath/min) are all in a physiological normal range. The in-flight protocol will be performed on L+4, L+5, L+6, and L+7 days.Upon return to Earth the subjects will undergo the same tests as in the pre-flight sessions on days R+0, R+1, R+2, R+4, R+5, R+15, R+16, R+25, R+30. (R=Return to Earth).