Aortic, cerebral and lower limb arterial and venous response to orthostatic stress after a 60-day bedrest.

The objective of this study is to assess by echography and Doppler the Cerebral (Vmca), Aortic (Vao) and Femoral (Vfem) arterial flow velocity and calf vein (Tibial, Gastrocnemius) section (Tib, Gast) during orthostatic intolerance (OI) test after a 60-day, head down tilt bed rest (HDBR). Twenty-four women (25-40 years) underwent a 60-day HDBR at -6°: eight as control (Con), eight with exercise against lower body negative pressure (Ex-Lb) and eight with nutrition supplement (Nut). Before and after (R0) HDBR, all subjects underwent a 10-min, 80° tilt followed by progressive LBNP until presyncope.

Quantification of muscle volume by echography: comparison with MRI data on subjects in long-term bed rest.

The objective of this study was to determine the accuracy of an echographic method for measuring the change in leg muscle volume against the gold standard, magnetic resonance imaging (MRI). Leg muscle volume was measured using an echographic scanner, which consisted of two metallic rails on which a probe holder moved via an electric engine. Ten to 20 transverse muscle views were collected along the area scanned, and the muscle cross-sectional area (CSA, cm2) was measured on each of them.

Insufficient flow reduction during LBNP in both splanchnic and lower limb areas is associated with orthostatic intolerance after bedrest.

We quantified the impact of a 60-day head-down tilt bed rest (HDBR) with countermeasures on the arterial response to supine lower body negative pressure (LBNP). Twenty-four women [8 control (Con), 8 exercise + LBNP (Ex-LBNP), and 8 nutrition (Nut) subjects] were studied during LBNP (0 to -45 mmHg) before (pre) and on HDBR day 55 (HDBR-55). Left ventricle diastolic volume (LVDV) and mass, flow velocities in the middle cerebral artery (MCA flow) and femoral artery (femoral flow), portal vein cross-sectional area (portal flow), and lower limb resistance (femoral resistance index) were measured.

Effect of the elastic compression stockings on the calf veins and tissues during a simulated orthostatic test (LBNP).

Unlabelled: The objective of the present study was to quantify the effects of elastic compression stockings (ECS) on the leg hemodynamics, the venous return (flow and distensibility) and on the leg superficial tissue thickness.

Material & Methods: 10 healthy women were submitted to LBNP (Lower Body Negative Pressure) tests without then with ECS (French pressure class 1, 2 and 3). The subject was instrumented with Doppler and echographic probes for assessing the femoral artery, the external saphenous and the gastrocnemian vein.

Tibial and gastrocnemian vein response to LBNP after a 60 day bedrest with and without counter-measures (WISE study).

Unlabelled: The objective was to quantify calf vein cross section area (CSA) maximal enlargement and the percent change in response to LBNP (lower body negative pressure) after a 60 day bedrest.

Method: The 24 healthy volunteers (25-40 y) of the WISE 60 day HDT(-6 degree) bedrest, were divided into 3 groups: Control (Co), Exercise countermeasure (Ex: treadmill under LBNP and flywheel), Nutrition (Nut: daily protein supplement). All were studied at -45mmHg LBNP pre and at HDT day 55.

WISE 2005: vascular responses to 60-day bed rest in women.

WISE-2005 studied 24 women during a 60-day head down bed rest (HDBR) who look part in an exercise countermeasure (LBNP-treadmill plus flywheel, EX) and no-exercise (No-EX). We conducted a series of experiments to explore changes in cardiovascular function and the ability of EX to prevent these changes. Resting arterial diameter in the arm was not affected but the leg arteries (femoral and popliteal) were significantly reduced in Np-EX, but was increased in EX.

Arterial and venous response to Tilt with LBNP test after a 60 day HDT bedrest (WISE study).

Unlabelled: The objective was to quantify the Cerebral, and Femoral arterial hemodynamics as well as the calf vein section changes induced by a Tilt up test continuing with a Tilt plus LBNP after a 60 day HDT (WISE).

Method: 24 healthy volunteers (25-40 y) underwent a 60 day HDT (-6 degree) bedrest: 8 as Control (Co), 8 with Exercise (Ex: treadmill under LBNP and flywheel), 8 with Nutrition (Nut: daily protein supplement). At R+0 all of them underwent a 10 min 80 degree Tilt up test, to which several LBNP period of 3 min were added (from -10 to -50 mmHg by steps of 10 mmHg) until presyncopal stage.

WISE-2005: tibial and gastrocnemius vein and calf tissue response to LBNP after a 60-day bed rest with and without countermeasures.

The objective of this study was to quantify by echography the changes in the intramuscular [gastrocnemius (Gast)] and nonintramuscular [posterior tibial (Tib)] calf veins cross-sectional area (CSA) and the superficial tissue thickness (STth) in response to lower body negative pressure (LBNP) after 60-day head-down bed rest (HDBR). Twenty-four healthy women (25-40 yr) were divided into three groups: control (Con), treadmill-LBNP and flywheel (Ex-Lb), nutrition (Nut; protein supplement). All underwent a LBNP (0 and -45 mmHg) before and on day 55 of HDBR.

WISE-2005: adrenergic responses of women following 56-days, 6 degrees head-down bed rest with or without exercise countermeasures.

We tested the hypotheses that women completing 56 days, 6 degrees head-down bed-rest (HDBR) would have changes in sensitivity of cardiovascular responses to adrenergic receptor stimulation and that frequent aerobic and resistive exercise would prevent these changes. Twenty-four women, eight controls, eight exercisers (lower body negative pressure treadmill and flywheel resistance exercise), and eight receiving nutritional supplement but no exercise were studied in baseline and during administration of the beta-agonist isoproterenol (ISO) and the alpha- and beta-agonist norepinephrine (NOR). In the control and nutrition groups, HDBR increased heart rate (HR) and reduced stroke volume (SV), and there was a significantly greater increase in HR with ISO after HDBR.

WISE 2005: stroke volume changes contribute to the pressor response during ischemic handgrip exercise in women.

The mechanism of the pressor response to small muscle mass (e.g., forearm) exercise and during metaboreflex activation may include elevations in cardiac output (Q) or total peripheral resistance (TPR).

Influence of eye closing on the cardiovascular response to stand test on stable and unstable platforms.

Unlabelled: Check if the stimulation of the leg muscles and neuro-sensorial system during stand test influence the cardiovascular response to stand test pre and post a 7 d HDT (4 subjects).

Methods: After 20 min supine, the subject stood for 10 min, and closed the eyes for 1 min. Then he stayed 2 min stand up on ant-posterior or lateral unstable platform and closed the eyes for 30 sec.

Assessment of the calf vein cross section change during stand-test after a 90 day bed rest by echography.

Objective: To evaluate the contribution of the calf veins distension during stand test to orthostatic intolerance (OI).

Method: The population consisted of a control group (Co, n=9) and an exercise (Fly-Wheel) counter-measure group (CM, n=9). Calf vein cross section area was assessed by echography during pre and post HDT stand-tests.

Portal vein cross-sectional area and flow and orthostatic tolerance: a 90-day bed rest study.

The objective of this study was to evaluate the changes in the portal vein cross-sectional area (PV CSA) and flow during a stand test associated with orthostatic intolerance. Eighteen subjects underwent a 90-day head-down tilt (HDT) bed rest at 6 degrees: 9 controls (Con) and 9 with flywheel exercise countermeasures (CM). At post-HDT, nine subjects (5 CM, 4 Con) were tolerant, and nine were intolerant.