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ABSTRACT: 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. After the post-HDBR Tilt + LBNP test, two groups were identified: finishers (F, n = 11) who completed the Tilt and non-finishers (NF, n = 13). A higher percentage decrease in Vao flow, higher percentage distension of Tib vein and a lack of increase in Vmca/Vfem ratio during the post-HDBR Tilt + LBNP compared to pre-HDBR were correlated to OI, but not all of these abnormal responses were present in each of the NF subjects. Abnormal responses were more frequent in Con and Nut than in Ex-Lb subjects. (1) HDBR did not affect the cardiac, arterial and venous responses to the orthostatic test to the same extent in each subject. (2) Exercise within LBNP partially preserved the cardiovascular response to Tilt, while Nutrition supplementation had no efficacy. (3) Cerebral/femoral flow ratio and aortic flow were the parameters most closely related to OI. (4) Reduction in aortic flow was not the major hemodynamic change preceding syncope.
Arbeitsphysiologie 05/2011; 112(1):277-84. · 2.15 Impact Factor
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P Arbeille,
J Ayoub,
V. Kieffer,
P. Ruiz,
B. Combes,
A. Coitrieux,
P Herve,
S. Garnier,
B. Leportz,
E. Lefbvre,
F Perrotin
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ABSTRACT: The objective of this paper is to design and validate a method for tele-operating (from an expert site) an echographic examination in an isolated site where the patient stays. A dedicated robotic arm (ESTELE) holding a real ultrasound probe is remotely controlled from the expert site with a fictive probe, and reproduces on the real probe all the movements of the expert hand. The isolated places, are areas with reduced medical facilities, secondary hospitals 20 to 100 km from the main hospital in Europe, dispensaries in Africa, Amazonia, the a rescue vehicles. ESTELE was tested on 87 adults and 29 pregnant with ISDN or satellite lines. During fetal tele-operated echography the expert was able to perform appropriate views of the fetal structures in 95% of the cases. During exploration of adult abdomen the expert visualized the main organs in 87% of the cases. Presently the ESTELE system is installed in 4 secondary hospitals, 40 to 100 km from our university hospital and tele-operated daily by our staff. Robotized tele-echography provide similar information as direct examination. No false diagnostic was reported. Moreover the patients were examined by an expert from the university hospital while staying in the Medical center proximal to their home.
Automation, Quality and Testing, Robotics, 2008. AQTR 2008. IEEE International Conference on; 06/2008
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ABSTRACT: 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. Subjects were identified as finisher (F) or nonfinisher (NF) of a 10-min tilt test after 60 days of HDBR. There were no differences in resting CSA of the Tib and Gast veins on HDBR day 55 compared with pre-HDBR for the Ex-Lb, Con and Nut, or the F groups; however, for NF both the Tib and Gast vein CSA at rest were significantly smaller after HDBR. At -45 mmHg LBNP, Tib and Gast CSAs were not significantly different from before HDBR in all groups (Ex-Lb, Con, Nut, F, NF). However, percent change in CSA of both veins from rest to -45 mmHg LBNP was significantly greater in the Con and Nut groups compared with Ex-Lb, and also NF compared with F. Similarly, the percent increase in STth on going from rest to -45 mmHg was higher after HDBR in the Con and Nut groups compared with Ex-Lb, as well as NF compared with F. These results showed that the Ex-Lb countermeasure minimized the bed rest effect on leg vein capacitance (CSA percent change) and STth increase during LBNP, whereas Nut had no effect and that higher leg vein and superficial tissue capacitance were associated with reduced orthostatic tolerance.
Journal of Applied Physiology 05/2008; 104(4):938-43. · 3.75 Impact Factor
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ABSTRACT: This study tested the hypothesis that cardiovascular and hormonal responses to lower body negative pressure (LBNP) would be altered by 4-h head down bed rest (HDBR) in 11 healthy young men. In post-HDBR testing, three subjects failed to finish the protocol due to presyncopal symptoms, heart rate was increased during LBNP compared with pre-HDBR, mean arterial blood pressure was elevated at 0, -10, and -20 mmHg and reduced at -40 mmHg, central venous pressure (CVP) and cardiac stroke volume were reduced at all levels of LBNP. Plasma concentrations of renin, angiotensin II, and aldosterone were significantly lower after HDBR. Renin and angiotensin II increased in response to LBNP only post-HDBR. There was no effect of HDBR or LBNP on norepinephrine while epinephrine tended to increase at -40 mmHg post-HDBR (P = 0.07). Total blood volume was not significantly reduced. Splanchnic blood flow taken from ultrasound measurement of the portal vein was higher at each level of LBNP post-compared with pre-HDBR. The gain of the cardiopulmonary baroreflex relating changes in total peripheral resistance to CVP was increased after HDBR, but splanchnic vascular resistance was actually reduced. These results are consistent with our hypothesis and suggest that cardiovascular instability following only 4-h HDBR might be related to altered hormonal and/or neural control of regional vascular resistance. Impaired ability to distribute blood away from the splanchnic region was associated with reduced stroke volume, elevated heart rate, and the inability to protect mean arterial pressure.
Journal of Applied Physiology 01/2008; 103(6):2018-25. · 3.75 Impact Factor
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ABSTRACT: 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).
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. Cerebral and Femoral flow changes were assessed by Doppler. Posterior Tibial, and Gastrocnemian vein were investigated by echography.
At Post HDT 10 min Tilt: cerebral flow decreased similarly in the 3 groups, but more in the non finishers than in the finishers, while the femoral decreased similarly in all groups. Leg vascular resistance and cerebral/femoral flow ratio increased less in the Co and Nut gr than in the Ex gr, and also in the non finishers than in the finishers. Percent increase in Gastrocnemian and Tibial section was higher in Co and Nut gr than in Ex gr, and in non finishers than in finishers.
Non exercise and non finisher subjects showed a lack of leg vasoconstriction, and a higher calf vein distensibility at post HDT Tilt test.
Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology 08/2007; 14(1):P47-8.
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ABSTRACT: 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.
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. Posterior Tibial (Tib), and Gastrocnemian (Gast) vein were investigated by echography using an echographic probe fixed at the upper and posterior part of the calf. From the post HDT CSE test the subjects were identified as finisher or non finisher to the 10-min tilt tolerance test.
At LBNP-45mmHg, the maximal enlargement of the Tib and Gast veins remained constant pre, and at HDT day 55 in all group (Co, Ex, Nut, finisher, non finisher). For both veins there was a higher vein distension (percent change from supine rest to -45mmHg) in Co and Nut group compared to Ex group despite the maximal distension was similar in all groups. Also the vein distension was higher in non finisher than in finisher.
The maximal distension of the vein were not affected nor by HDT nor by CM. The Ex counter-measure minimized the bed rest effect on leg vein distensibility (percent CSA change) while the Nut countermeasure had no effect. Higher leg vein distensibility was associated with reduced orthostatic tolerance.
Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology 08/2007; 14(1):P57-8.
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ABSTRACT: 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.
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.
1) At -40 mmHg the heart rate and blood pressure didn't change significantly with or without ECS. 2) The lower limb vascular resistance increased by 20 to 25% (p<0.01) from the initial values (i.e. without depressure) without or with class 1 or 2 ECS, while it increased less (13%, p<0.01) with class 3 ECS. 3) With ECS, the gastrocnemian vein area was reduced by 10 to 15% (p<0.01) from the initial values, in proportion to the ECS class. 4) The maximal distension (cross section) of this vein at -40 mmHg remained similar with or without ECS, but the percent change in vein distension was significantly higher with ECS than without. 5) Only without ECS, the distance between the external saphenous vein and the skin increased by 13% at -40 mmHg (p<0.01) from the initial values (increase of the calf peripheral area by 11% p<0.01). With ECS, there was no increase in distance nor area during LBNP.
ECS had no effect on the main arterial hemodynamics and venous cross section area, while it prevented liquid stowage into the superficial tissue.
Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology 08/2007; 14(1):P59-60.
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ABSTRACT: We tested the hypothesis that 60 days of head-down bed rest (HDBR) would affect cerebrovascular autoregulation and that this change would be correlated with changes in tolerance to the upright posture. Twenty-four healthy women (32 +/- 4 yrs) participated in a 60-d bed rest study at the MEDES Clinic in Toulouse, France. End tidal CO2 (ETCO2), continuous blood pressure (BP), middle cerebral artery (MCA) velocity and time to presyncope (endpoint) were measured during an orthostatic tolerance test conducted before/after bed rest. Given the large range of change in tolerance even within assigned countermeasure groups, we separated subjects for this analysis on the basis of the change in endpoint (Delta endpoint) pre- to post-bed rest. Autoregulation and CO2 responsiveness were evaluated on a different day from a two-breath test with intermittent hypercapnic exposure. Autoregressive moving average (ARMA) modeled the two confounding inputs, BP and CO2, on cerebrovascular blood flow. The cerebrovascular resistance index (CVRi) was expected to decrease following a decrease in BP at the MCA to assist in maintenance of cerebral blood flow. Subjects with the smallest Delta endpoint after bed rest had a 78% increase in the gain of the BP --> CVRi response. Meanwhile, the groups with greater decline in orthostatic tolerance post-HDBR had no change in the gain of this response. ETCO2 was lower overall following HDBR, decreasing from 41.8 +/- 3.4 to 40.2 +/- 3.0 in supine rest, 37.9 +/- 3.4 to 33.3 +/- 4.0 in early tilt, and 29.5 +/- 4.4 to 27.1 +/- 5.1 at pre-syncope. There was however, higher MCA velocity at any ETCO2 for post- compared to pre-HDBR. In summary, changes in autoregulation were found only in those subjects who had the smallest change from pre- to post-HDBR orthostatic tolerance. The changes may assist in buffering changes in cerebral blood flow during orthostatic hypotension post-HDBR. The reduction in ETCO2 after bed rest might be due to a change in chemoreceptor response to blood CO2, but the cerebrovascular system seems to have completely compensated.
Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology 08/2007; 14(1):P61-2.
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ABSTRACT: Twenty-four (24) healthy women from 25-40 years of age underwent orthostatic tolerance tests consisting of passive tilt and lower body negative pressure before and after completing 60-days of continuous -6 degree head down tilt bed rest (HDBR). Prior to HDBR, participants were assigned to one of three groups: control, exercise or nutrition. We aimed to identify any acute head up tilt changes in mean arterial pressure, pulse pressure, total peripheral resistance, cardiac output, stroke volume, or heart rate, which might predict tolerance or changes in tolerance with HDBR. Generally, these attempts were largely unsuccessful. The results indicate that the mechanisms of orthostatic failure are not strongly related to the way in which the body responds to the initial challenge. Additionally, the observation that some variables were predictive of tolerance before and not after tilt may indicate a change in the strategies used to maintain blood pressure, or differential adaptations to HDBR.
Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology 08/2007; 14(1):P63-4.
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ABSTRACT: 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). Increases in Q must be supported by reductions in visceral venous volume to sustain venous return as heart rate (HR) increases. Therefore, this study tested the hypothesis that increases in Q, supported by reductions in splanchnic volume (portal vein constriction), explain the pressor response during handgrip exercise and metaboreflex activation. Seventeen healthy women performed 2 min of static ischemic handgrip exercise and 2 min of postexercise circulatory occlusion (PECO) while HR, stroke volume and superficial femoral artery flow (Doppler), blood pressure (Finometer), portal vein diameter (ultrasound imaging), and muscle sympathetic nerve activity (MSNA; microneurography) were measured followed by the calculation of Q, TPR, and leg vascular resistance (LVR). Compared with baseline, mean arterial blood pressure (MAP) (P < 0.001) and Q (P < 0.001) both increased in each minute of exercise accompanied by a approximately 5% reduction in portal vein diameter (P < 0.05). MAP remained elevated during PECO, whereas Q decreased below exercise levels. MSNA was elevated above baseline during the second minute of exercise and through the PECO period (P < 0.05). Neither TPR nor LVR was changed from baseline during exercise and PECO. The data indicate that the majority of the blood pressure response to isometric handgrip exercise in women was due to mobilization of central blood volume and elevated stroke volume and Q rather than elevations in TVR or LVR resistance.
Journal of Applied Physiology 07/2007; 103(1):228-33. · 3.75 Impact Factor
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Ultrasound in Obstetrics and Gynecology 08/2006; 28(4):462 - 462. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 08/2006; 28(4):461 - 461. · 3.01 Impact Factor
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ABSTRACT: To design a method for conducting fetal ultrasound examinations in isolated hospital sites using a dedicated remotely controlled robotic arm (tele-echography).
Tele-echography was performed from our hospital (expert center) on 29 pregnant women in an isolated maternity hospital (patient site) 1700 km away, and findings were compared with those of conventional ultrasound examinations. At the patient site, a robotic arm holding the real ultrasound probe was placed on the patient's abdomen by an assistant with no experience of performing ultrasound. The robotic arm, remotely controlled with a fictive (expert) probe, reproduced the exact movements (tilting and rotating) of the expert hand on the real ultrasound probe.
In 93.1% of the cases, all biometric parameters, placental location and amniotic fluid volume, were correctly assessed using the teleoperated robotic arm. In two cases, femur length could not be correctly measured. The mean duration of fetal ultrasound examination was 14 min (range, 10-18) and 18 min (range, 13-23) by conventional and tele-echography methods, respectively. The mean number of times the robotic arm was repositioned on the patient's abdomen was seven (range, 5-9).
Tele-echography using a robotic arm provides the main information needed to assess fetal growth and the intrauterine environment within a limited period of time.
Ultrasound in Obstetrics and Gynecology 10/2005; 26(3):221-6. · 3.01 Impact Factor
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ABSTRACT: AIM: To study common femoral vein flow during simple movements and voluntary contractions of muscles of lower limbs in healthy volunteers and to evaluate the effects of elastic stocking on venous flow. METHODOLOGY: Experimental study. Ten subjects, aged 21 to 25 years, underwent duplex ultrasound to examine venous flow, the lower limb being fitted with sensors to characterize kinematics and of muscle activity. MOVEMENTS STUDIED: In supine position: thigh muscles contraction. forefoot dorsal flexion. Standing on both feet: thigh muscles contraction, tip-toe, front load transfer, extension of the leg on the knee, loading on one limb, forefoot back flexion. Data were recorded with a computerised system for secondary analysis. A mean venous velocity was calculated after elimination of parasite signals. Venous velocity was correlated with muscle signals. The procedure was repeated with the patient wearing a thigh-length class II elastic stockings (Varisma Innothera Ltd). RESULTS, CONCLUSION: All movements increased venous flow. Wearing elastic stockings increased the venous flush due to movements or muscle contractions. The level of muscle activity during the same movement or the same muscle contraction varied from one subject to the other.
Journal des Maladies Vasculaires 06/2005; 30(2):98-102. · 0.54 Impact Factor
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ABSTRACT: The aim of this study was to determine the effects of severe antenatal maternal anemia on pregnancy outcome.
and methods. A retrospective study comparing 2 groups of pregnant women: 111 (pregnant women) with anemia (Hb < 8 g/dl), 111 non- anemic pregnant women (Hb >10 g/dl). Clinical and biological characteristics for both groups were compared. Data on the newborn babies were collected.
In the anemic group: iron deficiency was the most common cause of anemia (92.7%). There was no significant difference between the 2 groups with respect to age or parity. Maternal anemia was found to be significantly associated with more frequent preterm birth (29.2% vs 9.2%) and increased low birth weight (2933 g vs 3159 g).
The literature is not conclusive on the influence of anemia in pregnant women. More frequent preterm birth and low birth weight have been reported in the majority of studies considering mild to moderate maternal anemia (in contrast to our study where the mothers had severe anemia). Many studies indicated that routine iron supplementation during pregnancy may have beneficial effects on pregnancy outcome. Severe anemia in pregnancy may have adverse effects for the newborn and should be treated or prevented early in pregnancy.
Journal de Gynécologie Obstétrique et Biologie de la Reproduction 10/2004; 33(6 Pt 1):506-9. · 0.42 Impact Factor
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Ultrasound in Obstetrics and Gynecology 08/2004; 24(3):242 - 242. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 08/2004; 24(3):282 - 282. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 08/2004; 24(3):299 - 299. · 3.01 Impact Factor
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ABSTRACT: The objective was to quantify bit by bit the arterial hemodynamic response to the successive acceleration induced fluid shifts during re-entry and landing. Method: The astronaut instrumented himself with a flat Doppler probe fixed on the skin, a blood pressure arm cuff, and 3 ECG electrodes. The ICMS (integrated cardiovascular monitoring system, 15x15x25 cu cm, battery powered) designed to monitor Blood pressure, ECG, cerebral and femoral flows was fixed below the astronaut sit in the middeck. Recordings started 5 minutes before de-orbiting (TIG) and stopped 5 min after wheels stop. Results. During re-entry blood pressure increased by 20% at TIG, and then by 25 to 30% during the highest Gz accelerations (approx 1 S g ) . The cerebral flow remained decreased by 10 to 15% below inflight value all during the Entry and landing phases. Conversely the femoral flow increased at TIG and entry ( + l0 to 20%), recovered at 0.lg, and then decreased in proportion with the Gz acceleration (-10% to -40% from 0.5g to 1.5g). The reduction in Femoral flow was associated with an opposite variation in lower limb vascular resistance. Consequently the cerebral flow/femoral flow ratio decreased at TIG and entry (-20%), and then increased according to the Gz acceleration level ( + l0 to +40% from 0.5 to 1.5g). Conclusion: During orthostatic tests (Stand LBNP tests) the cerebral to femoral flow ratio allowed to quantify the efficiency of the flow redistribution between these 2 areas and predicted orthostatic intolerance. In the present case the astronaut was found orthostatically tolerant at postflight tilt tests, but we suggest that during re-entry this parameter could predict the occurrence of syncope in severely disadapted astronauts.
08/2003;
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ABSTRACT: The objectives of this study were (a) to evaluate the sensitivity and specificity of foetal Doppler indices for the prediction of abnormal foetal heart rate (aFHR) at delivery after malaria crisis and (b) to test Doppler parameters against crisis duration for predicting aFHR. Every day during the malaria crisis, the umbilical and cerebral vascular resistance indices were measured by Doppler. These indices allowed evaluation of the amplitude of the foetal flow redistribution induced by malaria (C/U=cerebral resistance/umbilical resistance ratio), the duration of the flow redistribution period and the hypoxic index (mean %C/U change x crisis duration). It was found that the mean duration of the flow redistribution period was: 7 +/- 2 days, mean C/U change -7% +/- 4, hypoxic index -56 +/- 37, prematures 35%, and aFHR 17%. An hypoxic index > 150 predicted occurrence of aFHR with high sensitivity and specificity (100%/91%). The highest foetal flow disturbance (max %C/U) and the duration of the period with flow disturbance (> 7 days) predicted aFHR at delivery with a sensitivity of 10% and 40% and a specificity of 77% and 78%. It was concluded that the hypoxic index was more predictive of aFHR at delivery than the amplitude or the duration (i.e. crisis duration) of the foetal flow redistribution.
Parasitology 06/2003; 126(Pt 6):513-9. · 2.96 Impact Factor
