Philippe Arbeille

TER: A System for Robotic Tele-echography

The quality of ultrasound based diagnosis highly depends on the operators skills. Some healthcare centres may not have the required medical experts on hand when needed and therefore may not benefit from highly specialized ultrasound examinations. The aim of this project is to provide a reliable solution in order to perform expert ultrasound examinations in distant geographical areas and for the largest population possible. TER is a telerobotic system designed and developed by a French consortium composed of universities, hospitals and industrial companies. One originality of TER is the development of a compliant slave robot actuated by muscles. This slave robot is teleoperated by an expert clinician who remotely performs the exam. In this paper, we present the architecture of TER and describe its components.

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. Muscle sympathetic nerve activity (MSNA) was measured in the fibular nerve. Subjects were identified as finishers or nonfinishers of the 10-min post-HDBR tilt test. At HDBR-55, LVDV, mass, and portal flow were decreased from pre-HDBR (P < 0.05) in the Con and Nut groups only. During LBNP at HDBR-55, femoral and portal flow decreased less, whereas leg MSNA increased similarly, compared with pre-HDBR in the Con, Nut, and NF groups; 11 of 13 nonfinishers showed smaller LBNP-induced reductions in both femoral and portal flow (less vasoconstriction), whereas 10 of 11 finishers maintained vasoconstriction in either one or both regions. The relative distribution of blood flow in the cerebral versus portal and femoral beds during LBNP [MCA flow/(femoral + portal flow)] increased or reduced < 15% from pre-HDBR in 10 of 11 finishers but decreased > 15% from pre-HDBR in 11 of 13 nonfinishers. Abnormal vasoconstriction in both the portal and femoral vascular areas was associated with orthostatic intolerance. The vascular deconditioning was partially prevented by Ex-LBNP.

Use of a Robotic Arm to Perform Remote Abdominal Telesonography

OBJECTIVE The purpose of this study was to design and validate a method of performing sonography between an expert center and an isolated site. A sonography probe is held on the patient by a robotic arm and remotely controlled from the experts center. The robotic arm reproduces all the movements of the experts dummy probe on the patient probe. The system was tested on 87 patients at our hospital. CONCLUSION Robotic telesonography can be used for reliable diagnosis without moving the patient. No false diagnoses were made in this study. A bandwidth of 250 Kbps via integrated services digital network or satellite is required for reliable diagnosis. Such a system can provide diagnostic information that is currently unavailable in isolated or inaccessible areas and on rescue vehicles.

ECHOGRAPHIC EXAMINATION IN ISOLATED SITES CONTROLLED FROM AN EXPERT CENTER USING A 2-D ECHOGRAPH GUIDED BY A TELEOPERATED ROBOTIC ARM

The objective of the present project was to design and validate a method for teleoperating (from an expert site) an echographic examination in an isolated site. A dedicated robotic arm holding a real ultrasound (US) 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, 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). These sites are linked to the expert one by ISDN (numeric) telephone or satellite lines. At the expert center, the US medical expert moves a fictive probe, connected to a computer (no. 1) that sends the coordinate changes of this probe via an ISDN or satellite line to a second computer (no. 2), located at the isolated site, that applies them to the robotic arm holding the real echographic probe. The system was tested on 20 patients. In all cases, the expert was able to perform the main views (longitudinal, transverse) of the liver, gallbladder, kidneys, aorta, pancreas, bladder, prostate and uterus as during direct examination on the patient. The heart and spleen were not visualized in 2 and 4 of the 20 cases, respectively. The mean duration of the robotized echography (27 +/- 7 min for three to four organs) was approximately 50% longer than direct echography of the patient.

Cardiovascular regulation during long-duration spaceflights to the International Space Station.

Early evidence from long-duration flights indicates general cardiovascular deconditioning, including reduced arterial baroreflex gain. The current study investigated the spontaneous baroreflex and markers of cardiovascular control in six male astronauts living for 2-6 mo on the International Space Station. Measurements were made from the finger arterial pressure waves during spontaneous breathing (SB) in the supine posture pre- and postflight and during SB and paced breathing (PB, 0.1 Hz) in a seated posture pre- and postflight, as well as early and late in the missions. There were no changes in preflight measurements of heart rate (HR), blood pressure (BP), or spontaneous baroreflex compared with in-flight measurements. There were, however, increases in the estimate of left ventricular ejection time index and a late in-flight increase in cardiac output (CO). The high-frequency component of RR interval spectral power, arterial pulse pressure, and stroke volume were reduced in-flight. Postflight there was a small increase compared with preflight in HR (60.0 ± 9.4 vs. 54.9 ± 9.6 beats/min in the seated posture, P < 0.05) and CO (5.6 ± 0.8 vs. 5.0 ± 1.0 l/min, P < 0.01). Arterial baroreflex response slope was not changed during spaceflight, while a 34% reduction from preflight in baroreflex slope during postflight PB was significant (7.1 ± 2.4 vs. 13.4 ± 6.8 ms/mmHg), but a smaller average reduction (25%) during SB (8.0 ± 2.1 vs. 13.6 ± 7.4 ms/mmHg) was not significant. Overall, these data show no change in markers of cardiovascular stability during long-duration spaceflight and only relatively small changes postflight at rest in the seated position. The current program routine of countermeasures on the International Space Station provided sufficient stimulus to maintain cardiovascular stability under resting conditions during long-duration spaceflight.

Modelflow estimates of cardiac output compared with Doppler ultrasound during acute changes in vascular resistance in women

We compared Modelflow (MF) estimates of cardiac stroke volume (SV) from the finger pressure‐pulse waveform (Finometer®) with pulsed Doppler ultrasound (DU) of the ascending aorta during acute changes in total peripheral resistance (TPR) in the supine and head‐up‐tilt (HUT) postures. Twenty‐four women were tested during intravenous infusion of 0.005 or 0.01 μg kg−1 min−1 isoprenaline, 10 or 50 ng kg−1 min−1 noradrenaline and 0.3 mg sublingual nitroglycerine. Responses to static hand‐grip exercise (SHG), graded lower body negative pressure (LBNP, from −20 to −45 mmHg) and 45 deg HUT were evaluated on separate days. Bland–Altman analysis indicated that SVMF yielded lower estimates than SVDU during infusion of 0.01 μg kg−1 min−1 isoprenaline (SVMF 92.7 ± 15.5 versus SVDU 104.3 ± 22.9 ml, P= 0.03) and SHG (SVMF 78.8 ± 12.0 versus SVDU 106.1 ± 28.5 ml, P < 0.01), while larger estimates were recorded with SVMF during −45 mmHg LBNP (SVMF 52.6 ± 10.7 versus SVDU 46.2 ± 14.5 ml, P= 0.04) and HUT (SVMF 59.3 ± 13.6 versus SVDU 45.2 ± 11.3 ml, P < 0.01). Linear regression analysis revealed a relationship (r2= 0.41, P < 0.01) between the change in TPR from baseline and the between‐methods discrepancy in SV measurements. This relationship held up under all of the experimental protocols (regression for fixed effects, P= 0.46). These results revealed a discrepancy in MF estimates of SV, in comparison with those measured by DU, during acute changes in TPR.

The TERESA project : from space research to ground tele‐echography

Ultrasound examinations represent one of the major diagnostic modalities of future healthcare. They are currently used to support medical space research but require a high skilled operator for both probe positioning on the patients skin and image interpretation. TERESA is a tele-echography project that proposes a solution to bring astronauts and remotely located patients on ground quality ultrasound examinations despite the lack of a specialist at the location of the wanted medical act.

Effect of long-term cocaine administration to pregnant ewes on fetal hemodynamics, oxygenation, and growth.

Objective To assess uterine and fetal blood flows by Doppler velocimetry and fetal growth and oxygenation in pregnant ewes treated daily with cocaine and to determine whether cocaine impairs fetal cardiac and cerebral reactivity. Methods The study groups received 70 mg (n = 7) or 140 mg (n = 7) of cocaine and the control group (n = 7) received placebo injected intramuscularly daily on days 60–134. Hemodynamic data were measured at rest and during two acute hypoxic tests at cesarean delivery performed on day 134. Results The fetal heart rate (FHR) and umbilical and uterine resistance indices (RIs) were higher in the cocaine groups than in the control group (FHR: 187 ± 8 and 166 ± 8 beats per minute at 83 and 123 days, respectively, in controls and 9–11% higher in cocaine groups; umbilical RI: 0.79 ± 0.06, 0.60 ± 0.04, and 0.52 ± 0.06, at 83, 105, and 123 days, respectively, in controls and 11–17% higher in the cocaine groups [P <.01]; and uterine RI: 0.40 ± 0.05, 0.40 ± 0.04, and 0.37 ± 0.04, at 83, 105, and 123 days, respectively, in controls and 13–35% higher in cocaine groups [P <.05]). At delivery on day 134, the following characteristics were found to be different in the cocaine groups: fetal weight (4.03 ± 0.2 kg in controls and 15–21% lower in the cocaine groups [P <.02]), partial pressure of oxygen (26.5 ± 1.4 mmHg in controls and 15–16% lower in cocaine groups [P <.05]), umbilical RI (0.40 ± 0.03 in controls and 11–17% higher in cocaine groups [P <.01]), cerebral RI (0.61 ± 0.03 in controls and 9–15% lower in cocaine groups [P <.01]), and cerebral-umbilical ratio (1.52 ± 0.04 in controls and 22–23% lower in cocaine groups [P <.001]). During the hypoxic tests, the cerebral RI (P <.05) and the cerebral-umbilical ratio (P <.05) decreased significantly less in the two cocaine groups. The FHR response was reduced significantly less in the two cocaine groups (P <.05). Conclusion Long-term exposure to cocaine induces uterine and fetal blood flow disorders, fetal growth restriction, and hypoxia. It reduces the capability of the cerebral vessels to vasodilate and the heart rate to increase during acute hypoxia.

Calf venous volume during stand-test after a 90-day bed-rest study with or without exercise countermeasure

The objectives to determine both the contribution to orthostatic intolerance (OI) of calf venous volume during a stand‐test, and the effects of a combined eccentric–concentric resistance exercise countermeasure on both vein response to orthostatic test and OI, after 90‐day head‐down tilt bed‐rest (HDT). The subjects consisted of a control group (Co‐gr, n= 9) and an exercise countermeasure group (CM‐gr, n= 9). Calf volume and vein cross‐sectional area (CSA) were assessed by plethysmography and echography during pre‐ and post‐HDT stand‐tests. From supine to standing (post‐HDT), the tibial and gastronemius vein CSA increased significantly in intolerant subjects (tibial vein, +122% from pre‐HDT; gastronemius veins, +145%; P < 0.05) whereas it did not in tolerant subjects. Intolerant subjects tended to have a higher increase in calf filling volume than tolerant subjects, in both sitting and standing positions. The countermeasure did not reduce OI. Absolute calf volume decreased similarly in both groups. Tibial and gastrocnemius vein CSA at rest did not change during HDT in either group. During the post‐HDT stand‐test, the calf filling volume increased more in the CM‐gr than in the Co‐gr both in the sitting (+1.3 ± 5.1%, vs.–7.3 ± 4.3%; P < 0.05) and the standing positions (+56.1 ± 23.7%vs.+1.6 ± 9.6%; P < 0.05). The volume ejected by the muscle venous pump increased only in the CM‐gr (+38.3 ± 21.8%). This study showed that intolerant subjects had a higher increase in vein CSA in the standing position and a tendency to present a higher calf filling volume in the sitting and standing positions. It also showed that a combined eccentric–concentric resistance exercise countermeasure had no effects on either post‐HDT OI or on the venous parameters related to it.

Ultrasound in space.

Physiology of the human body in space has been a major concern for space-faring nations since the beginning of the space era. Ultrasound (US) is one of the most cost effective and versatile forms of medical imaging. As such, its use in characterizing microgravity-induced changes in physiology is being realized. In addition to the use of US in related ground-based studies, equipment has also been modified to fly in space. This involves alteration to handle the stresses of launch and different power and cooling requirements. Study protocols also have been altered to accommodate the microgravity environment. Ultrasound studies to date have shown a pattern of adaptation to microgravity that includes changes in cardiac chamber sizes and vertebral spacing. Ultrasound has been and will continue to be an important component in the investigation of physiological and, possibly, pathologic changes occurring in space or as a result of spaceflight.