Past scientific projects
Spaceflight (7d 14months) HDT 4-90days
During most short term flights (7 to 30 days) or HDT (Head down tilt) of the same duration, a significant reduction of the left ventricle size in diastole was observed and supposed to correspond to a hypovolemia since in HDT it was associated with a reduction in plasma volume of similar amplitude (Maillet et al 1996, Hughson et al 1995). In-flight no modification of the cardiac contractility was found, nor any significant decrease of the myocardium thickness, whereas in long-term HDT myocardial atrophy has been reported (Bungo et al 1985; 1989, Charles et al 1991, Arbeille et al 1992; 1998, Hughson et al 1995, Convertino et al 1996, Maillet et al 1996, Blomquist et al 1996, Levine et al 1997).
The exposure to actual or simulated microgravity was found to reduce the vascular resistance in central organs like the kidney, and in peripheral areas like the lower limbs (Arbeille et al 1992; 1996b; 1998). Proximal leg vein (femoral) cross-sectional area increased in-flight (Arbeille et al 1994) but decreased in HDT, whereas the calf vein compliance increased in HDT (Buckey et al 1988, Convertino et al 1989, Louisy et al 1995, Tyberg et al 1996).
Despite the fact that cerebral flow in-flight was stable and close to the preflight level, the jugular vein cross section remained enlarged and the facial edema was always present due to the presence of the venous stasis at this level throughout the flight (Arbeille et al 1996b). These observations and others collected during HDT studies suggest that in-flight the intracranial pressure may increase in association with a possible brain edema (Murphy et al 1992, Frey et al 1993).
A passive countermeasure called a "bracelet" has been designed by the Institut of biophysic of Moscow (Dr Alexandre Yarov) to reduce the cephalic edema and make the adaptation to 0 g more comfortable. This method consists of 2 cuffs placed at the upper part of the thighs which apply a pressure of approximately 30 mmHg (Arbeille et al 1996b). The bracelets were considered to reduce the venous return by trapping a significant amount of fluid into the lower limb vascular and interstitial space. During a 14 day spaceflight we noticed that the vascular resistances increased in several areas (kidney, lower limbs) when the cosmonaut wore the bracelets. This observation led us to suspect that the use of the bracelets during daytime as recommended to the astronauts to improve their comfort may be responsible for significant cardiovascular changes.
On the other hand it was observed that despite the fact that the cardiovascular system reaches a stable equilibrium after some days in space, cardiovascular deconditioning always develops, leading to orthostatic intolerance when returning to 1 g gravity or after HDT (Arbeille et al 1996a, and 1998, Buckey et al 1996, Convertino et al 1990, Fritsch et al 1992, Sigaudo et al 1996, Robertson et al 1996).
Several Bedrest (HDT -6° 4-90 days) and inflight (1week 14month onboard MIR) studies were designed to a) confirm the changes in Cardiac arterial and venous changes, b) to evaluate the efficiency of various countermeasures like Exercise (aerobic, resistive) LBNP, Artificial gravity, thigh cuffs…(see download papers 1995 - 2008).
The exposure to actual or simulated microgravity was found to reduce the vascular resistance in central organs like the kidney, and in peripheral areas like the lower limbs (Arbeille et al 1992; 1996b; 1998). Proximal leg vein (femoral) cross-sectional area increased in-flight (Arbeille et al 1994) but decreased in HDT, whereas the calf vein compliance increased in HDT (Buckey et al 1988, Convertino et al 1989, Louisy et al 1995, Tyberg et al 1996).
Despite the fact that cerebral flow in-flight was stable and close to the preflight level, the jugular vein cross section remained enlarged and the facial edema was always present due to the presence of the venous stasis at this level throughout the flight (Arbeille et al 1996b). These observations and others collected during HDT studies suggest that in-flight the intracranial pressure may increase in association with a possible brain edema (Murphy et al 1992, Frey et al 1993).
A passive countermeasure called a "bracelet" has been designed by the Institut of biophysic of Moscow (Dr Alexandre Yarov) to reduce the cephalic edema and make the adaptation to 0 g more comfortable. This method consists of 2 cuffs placed at the upper part of the thighs which apply a pressure of approximately 30 mmHg (Arbeille et al 1996b). The bracelets were considered to reduce the venous return by trapping a significant amount of fluid into the lower limb vascular and interstitial space. During a 14 day spaceflight we noticed that the vascular resistances increased in several areas (kidney, lower limbs) when the cosmonaut wore the bracelets. This observation led us to suspect that the use of the bracelets during daytime as recommended to the astronauts to improve their comfort may be responsible for significant cardiovascular changes.
On the other hand it was observed that despite the fact that the cardiovascular system reaches a stable equilibrium after some days in space, cardiovascular deconditioning always develops, leading to orthostatic intolerance when returning to 1 g gravity or after HDT (Arbeille et al 1996a, and 1998, Buckey et al 1996, Convertino et al 1990, Fritsch et al 1992, Sigaudo et al 1996, Robertson et al 1996).
Several Bedrest (HDT -6° 4-90 days) and inflight (1week 14month onboard MIR) studies were designed to a) confirm the changes in Cardiac arterial and venous changes, b) to evaluate the efficiency of various countermeasures like Exercise (aerobic, resistive) LBNP, Artificial gravity, thigh cuffs…(see download papers 1995 - 2008).