24-Hour Pattern of Blood Pressure and Heart Rate in Weightlessness (Circa) - 03.04.14
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University of Amsterdam, Amsterdam, , Netherlands
Sponsoring Space Agency
European Space Agency (ESA)
ISS Expedition Duration
October 2003 - October 2004
Previous ISS Missions
The experiment aims to measure the pattern of blood pressure and heart rate during a 24-hr period in an astronaut. The combined data from 2 instruments used in this experiment will enable the team to unravel the underlying physiology of circadian cardiovascular control in weightlessness. The experiment will do so by: repeated measurement of upper arm cuff pressure by an automated, portable device (BMI) and continuous measurement of finger blood pressure (Portapres) and therefore heart rate.
The total duration of each experimental session is 25 hr hours. During each session the following activities are executed: recording with the Bloodpressure Measurement Instrument (BMI) during 25 hours two specific protocols (one during the morning : protocol 1, one during the afternoon : protocol 2) with Portapres recording and BMI off. Portapres recording session as long as possible within the 25h. The following periods are of very high importance for science: From the beginning of lunch until 30 minutes after the end of lunch From the beginning of dinner until 30 minutes after the end of dinner From one hour before the cosmonaut goes to sleep until minimum one hour after the transition awake-sleep. Recording can last until the end of the sleep phase if the battery capacity allows it. From wake up until one hour after wake up. The cosmonaut shall do his normal work during the day of the experiment. The in-flight part of the experiment will be conducted in the Russian module of ISS, and will be repeated twice at the beginning and at the end of the flight. The overall experiment has two pre-flight baseline data collection sessions. The post-flight part of the experiment will record return to normal gravity circumstances. This part will also be performed twice.
This study has shown that astronauts on short-lasting spaceflight may be subject to strong psychological stimuli. In particular ?official? moments like press-conferences can induce surges of blood pressure and heart rate. The authors recorded in-flight 24-hour profiles of BP and HR in 2 ESA-astronauts by automatic upper arm cuff measurements; in one astronaut this was combined with continuous finger blood pressure monitoring, which allows additional estimation of cardiac output and vascular resistance.
The initial hypothesis was that spaceflight would show the same day/night changes as had been observed earlier in ground based (Head Down Tilted ? HDT) simulation studies. However, unlike the simulations, BP and HR were not very much changed in-flight from preflight. Only daytime diastolic pressures (both subjects) and nighttime HR (for one subject) were significantly lower in-flight than preflight. Actual space flight did not confirm the earlier HDT findings for BP-levels and for daytime to nighttime changes. Daytime BP-levels were definitely higher than was expected; strikingly, BP- and HR-surges during the working days in space were often related to stressful moments like live media events, but were not restricted to these moments. The authors hypothesize that the busy work schedule of short-stay astronauts adds to the general level of arousal that is apparent from the measurements.
This study shows that extensive in-flight cardiovascular measurements are feasible, even in busy astronauts, while they are performing their normal duties. From these observations, researchers have learned to take the psychological aspects of spaceflight more into account when judging the adaptation to microgravity. (Karemaker et al., 2009).
Karemaker JM, Berecki-Gisolf J. 24-h Blood Pressure in Space: The Dark Side of Being an Astronaut. Respiratory Physiology and Neurobiology. 2009; 169 Suppl: S55-S58.
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