Telesonography: virtual 3D image processing of remotely acquired abdominal, vascular, and fetal sonograms.

PURPOSE: To design and test a new telesonography technique using remote volume acquisition by untrained operators in locations without access to trained sonographers, postprocessing, and interpretation done at expert centers. MATERIALS AND METHODS: The technique was tested with 84 sonograms of organs acquired in pregnant women (n = 8) and patients with various abdominal pathologic conditions (n = 11) located in French Guyana (France), Ceuta (Spain), and Murighiol (Romania). An operator inexperienced in sonography (US) placed the transducer over the predetermined acoustic window for each organ, then swept it from a -45° to a +45° position to scan the targeted organ. The acquired volume dataset was sent to an expert center via the Internet and reconstructed using a proprietary software, which allowed a trained sonographer to navigate through the appropriately reconstructed sonograms. RESULTS: After three-dimensional processing at the expert center, the organs scanned in the obstetrical cases were adequately visualized by the expert in seven of eight (88%) examinations of the fetal head, femur, and umbilical cord and eight of eight (100%) examinations of the fetal abdomen and placenta, whereas in the general abdominal cases, the liver, gallbladder, portal vein, and right kidney were correctly visualized in 10 of 11 (91%) examinations. CONCLUSIONS: Telesonography allowed untrained operators to scan and transfer the US volume datasets over the Internet to an expert center where an expert sonographer could navigate through the reconstructed US volume and visualize sonograms of diagnostic quality.

Impaired cerebrovascular autoregulation and reduced CO2 reactivity after long duration spaceflight.

Long duration habitation on the International Space Station (ISS) is associated with chronic elevations in arterial blood pressure in the brain compared with normal upright posture on Earth and elevated inspired CO(2). Although results from short-duration spaceflights suggested possibly improved cerebrovascular autoregulation, animal models provided evidence of structural and functional changes in cerebral vessels that might negatively impact autoregulation with longer periods in microgravity. Seven astronauts (1 woman) spent 147 ± 49 days on ISS. Preflight testing (30-60 days before launch) was compared with postflight testing on landing day (n = 4) or the morning 1 (n = 2) or 2 days (n = 1) after return to Earth. Arterial blood pressure at the level of the middle cerebral artery (BP(MCA)) and expired CO(2) were monitored along with transcranial Doppler ultrasound assessment of middle cerebral artery (MCA) blood flow velocity (CBFV). Cerebrovascular resistance index was calculated as (CVRi = BP(MCA)/CBFV). Cerebrovascular autoregulation and CO(2) reactivity were assessed in a supine position from an autoregressive moving average (ARMA) model of data obtained during a test where two breaths of 10% CO(2) were given four times during a 5-min period. CBFV and Doppler pulsatility index were reduced during -20 mmHg lower body negative pressure, with no differences pre- to postflight. The postflight indicator of dynamic autoregulation from the ARMA model revealed reduced gain for the CVRi response to BP(MCA) (P = 0.017). The postflight responses to CO(2) were reduced for CBFV (P = 0.056) and CVRi (P = 0.047). These results indicate that long duration missions on the ISS impaired dynamic cerebrovascular autoregulation and reduced cerebrovascular CO(2) reactivity.

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. In this study we report on drug stimulated responses with sublingual nitroglycerin and infused isoproterenol. Heart rate increased in response to nitroglycerin with larger increases in No-EX after HDBR. Likewise during isoproterenol infusion the HR increase was greater after HDBR in the No-EX group. In all cases, the higher HR was associated with lower stroke volume in No-EX while stroke volume was protected in EX. These data do not support a change in sensitivity of beta-adrenergic receptors after HDBR. The leg vascular resistance decreased in response to isoproterenol and it decreased to a greater extent in No-EX than EX. These data were consistent with observations of lower leg vascular resistance during orthostatic challenge tests after HDBR. We conclude that consistent changes in cardiovascular function in the No-EX were detected by different methods that point to mechanisms contributing to orthostatic intolerance after HDBR.

WISE 2005: flow and nitroglycerin mediated dilation following 56 days of head down tilt bed rest with and without an exercise countermeasure.

This investigation set out to determine the effect of 56 days of head-down tilt bed rest (HDBR) and an exercise countermeasure on endothelial dependent and independent vascular function. 24women took part in this study. 8 subjects completed lower body resistance and aerobic exercise (EX, treadmill running 3-4 days per week for 40-min followed by 10-min of static LBNP, and resistive exercise on a flywheel device every 3rd day) and 16 subjects were considered as non-exercisers in a control group and a protein supplement group. FMD was induced by release of distal limb ischemia and NMD by sublingual administration of 0.3 mg of nitroglycerin before and after HDBR. Preliminary results of this study suggest that HDBR without EX results in a decreased resting diameter of the popliteal while EX increased the diameter. It is also suggested that FMD was elevated without exercise in both brachial and popliteal arteries, while pre-HDBR FMD was preserved by EX in the popliteal, but not the brachial artery. NMD appears to be elevated in the popliteal and femoral in the absence of exercise, but unchanged in the brachial artery or at any site for EX.

Abdominal and fetal echography tele-operated in several medical centres sites, from an expert center, using a robotic arm & telephone or satellite link.

OBJECTIVE: to design and validate a method for tele-operating (from an expert site) an echographic examination in an isolated site where the patient stays. METHOD: 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 Europ, dispensaries in Africa, Amazonia, the a rescue vehicles.... RESULTS: 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. CONCLUSION: 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.

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. RESULTS: Tibial, and muscular vein section at rest did not change during HDT in both groups. From supine to standing, the Tibial and muscular vein section increased significantly more at post HDT in non tolerant subjects, compare to pre HDT (tibial V: +122% from pre-HDT, muscular V: +145% p<005). In tolerant subjects the vein cross section increase from supine to stand was similar pre and post HDT. CONCLUSION: Fly-Wheel CM, did not reduce OI. High calf vein section increase at post-HDT stand-test compare to pre-HDT was significantly correlated with OI but not with CM.

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. The cerebral and lower limb flow were assessed by Doppler (skin fixed sensors) and also the cerebral to femoral flow ratio (CFR). RESULTS: All 4 subjects were tolerant, CFR increased similarly pre and post HDT. Post HDT eye closing increased leg muscle activity, and femoral flow increased more than pre HDT, on ant-post unstable platform. The trace of the body foot pressure point was much longer post HDT on the ant-post platform. CONCLUSION: Post HDT neuro-sensorial disadaptation may contribute to reduce the orthostatic tolerance at least in absence of visual references.

Splanchnic and peripheral vascular resistance during lower body negative pressure (LBNP) and tilt.

We tested the hypothesis that vasoconstriction in response to LBNP or head up tilt would be reflected in a reduction in splanchnic (portal vein) blood flow (PVF) and increases in forearm and total peripheral vascular resistance (TPR). Changes in vascular resistance indicators were obtained from measurement of PVF from portal vein cross-sectional area and blood velocity by Doppler ultrasound, from forearm vascular resistance (FVR, by Doppler) and total peripheral resistance (TPR, by impedance cardiography). 21 subjects were tested during LBNP (0, -10, -20 and -30 mmHg) and 9 subjects during tilt (0, 45 and 70 degrees). During progressive LBNP, PVF decreased approximately linearly with LBNP (-30, -48 and -64% at -10, -20 and -30 mmHg) and with tilt angle (-39 and -58% at 45 and 70 degrees). The increase in FVR approximately mirrored these changes during LBNP (20.1, 44.7 and 55.3%) and tilt (45.6 and 63.6%). However, the changes in TPR during LBNP (12.0, 16.9 and 26.4%) and tilt (25.2 and 29.2%) were markedly less. This observation of different percent changes in forearm versus total peripheral resistance might reflect true physiological differences in the forearm (and splanchnic) circulations compared with the whole body, or the data might suggest that impedance cardiography did not provide a reliable indicator of cardiac output and therefore TPR under these conditions. The primary observation in this study was that Doppler ultrasound measurement of portal vein blood flow provided a non-invasive estimate of splanchnic vascular resistance during postural or LBNP challenge and that using the reduction in portal vein flow as an index of increased vasoconstriction paralleled the change in forearm vascular resistance.

The robot and the satellite for tele-operating echographic examination in Earth isolated sites, or onboard ISS.

UNLABELLED: The objective was to design and validate a method for tele-operating (from an expert site) an echographic examination in an isolated site. METHOD: The isolated places, defined as areas with reduced medical facilities, could be secondary hospitals 20 to 50 km from the university hospital, or dispensaries in Africa or Amazonia, or a moving structure like a rescue vehicle or the International Space Station (ISS). At the expert center, the ultrasound medical expert moves a fictive probe, connected to a computer (n degrees 1) which sends, the coordinate changes of this probe via an ISDN or satellite line to a second computer (n degrees 2), located at the isolated site, which applies them to the robotic arm holding the real echographic probe. RESULTS: The system was tested at Tours Hospital on 105 patients. A complete investigation (visualization) of all the organs requested for different clinical cases was obtained in 76% of the cases with the robot, and 87% at the reference echography: In 11% of the cases, at least one of the organ visualized at reference echo could not be investigated by the robot, thus the diagnostic was not done. The number of repositioning was higher for the robot (6.5 +/- 2) than for the reference echo (5.1 +/- 2 = or > 24% more with robot). The duration of the examination was higher with the robot (16 +/- 10 min) than for the reference echography (11 +/- 4 min = or > +43% with the robot compare to reference echography. The system was also tested successfully using satellite links in a limited number of cases (approx 30).

Diaphragm kinetics during pneumatic belt respiratory assistance: a sonographic study in Duchenne muscular dystrophy.

The principal aim of this study was to demonstrate the usefulness of M-mode sonography as a noninvasive technique to evaluate diaphragm excursion. The secondary aim was to assess the efficacy of pneumatic abdomino-diaphragmatic belt ventilation in patients with Duchenne muscular dystrophy. Using M-mode sonography, we measured the amplitude of diaphragm excursion in seven patients with Duchenne muscular dystrophy in various positions (0 degrees, 45 degrees, 75 degrees ) with and without pneumatic abdomino-diaphragmatic belt respiratory assistance. The belt significantly increased mean amplitude of diaphragm excursion by 62% at 45 degrees and by 55% at 75 degrees, and increased mean tidal volume by 43.5% at 45 degrees and by 49% at 75 degrees. Two patients were unable to tolerate the horizontal position (0 degrees ) During quiet breathing without the belt, amplitude of diaphragm excursion and tidal volume were positively correlated at 45 degrees (r=0.81; P=0.027) and 75 degrees (r=0.75; P=0.05). There was a significant intra-individual correlation between these two parameters during belt use but no inter-individual correlation. Without the belt, thoracic posture had no significant effect on amplitude of diaphragm excursion, either in quiet or deep breathing. After overnight respiratory assistance, arterial oxygen pressure and arterial oxygen saturation increased significantly, and arterial carbon dioxide pressure decreased from 52+/-6.4 to 46.4+/-4 mmHg. The pneumatic abdomino-diaphragmatic belt significantly improved gas exchanges and ventilation by increasing diaphragm excursion, as was clearly shown by noninvasive M-mode sonography. Indeed, M-mode sonography may be helpful in pneumatic abdomino-diaphragmatic belt pressure adjustment.

Influence of otoliths and neck muscle receptors on peripheral hemodynamic regulation.

To evaluate the cardiovascular changes induced by otoliths and neck mechanoreceptors stimulation during head movements, nine subjects in supine prone position performed passive head-down neck flexion (P.Ext) and head up P.Extension (P.Flex) As the lower limbs vasoconstricted from P.Ext to P.Flex, it is suggested that the otoliths stimulation towards the base of the head (like in standing position) contribute to reduce the vasoconstriction whereas when stimulated towards the top of the head (head flexion) they increase it.

Venous stagnation induced by 7 days in HDT, in the cerebral, ophthalmic, renal and splanchnic territories.

The scientific objectives was to quantify the vascular changes in the brain, eye fundus, renal parenchyma, and splanchnic network. Heart, portal, jugular, femoral veins were investigate by Echography. The cerebral mesenteric, renal and ophthalmic arteries were investigated by Doppler. Eye fundus vein an papilla were investigated by optical video eye fundus. The left ventricle volume decreased as usual in HDT. The cerebral and ophthalmic vascular resistances didn't change whereas the eye fundus papilla and vein, and the jugular vein increased. These arterial and venous data confirm the existence of cephalic venous blood stasis without sign of intracranial hypertension. On the other hand the kidney volume increased which is in agreement with blood flow stagnation at this level. At last the mesenteric vascular resistance decreased and the portal vein section increased in HDT which is in favor of an increase in flow and flow volume through the splanchnic area.

[Doppler monitoring of fetal circulation from multiple arteries over several days to improve evaluation of fetal prognosis]. / Monitoring Doppler de la circulation foetale sur plusieurs artères et sur plusieurs jours pour une meilleure prédiction du devenir foetal.

Intrauterine growth retardation and fetal hypoxia are currently related to placental insufficiency. Fetal biometry assessed by echography is entirely adapted to follow the growth and integrity of the principal fetal organs. Hypoxia induces an hemodynamic adaptation which can be detected and quantified by Doppler. The objective of this article is to review the evolution of the fetal Doppler practice for the last 20 years and especially to show that isolated Doppler measurement and only from one site (umbilical or cerebral or aortic) have a moderate negative predictive value of fetal outcome, compared to the study of the fetal hemodynamic evolution (degradation) from several sites and during several days. We will insist on the fact that (a) umbilical Doppler only gives information on placental blood flow and this information does not reflect neither the adaptation to hypoxia nor the consequences of this adaptation, (b) cerebral Doppler accounts for the vascular response to the pO(2) reduction but it does not allow to predict the consequences of this response, (c) the simultaneous study of the placental hemodynamic time course degradation and the cerebral vascular response to hypoxia allows quantification of the cumulative deficit of fetal oxygenation during this period and evaluation the adverse consequences of a sustained flow redistribution toward the brain. Finally, if cerebral vasodilation in response to hypoxia can be considered as a physiological compensatory mechanism, it is associated after several days to the appearance of irreversible fonctional (abnormal fetal heart rate) or organic (cerebral lesions) abnormalities. Adverse effects of this process are illustrated during episodes of acute hypoxia (malaria crisis of several days) or during sustained exposure of the fetus to hypoxia (pregnancy-induced hypertension).