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Biomedical subjects

O Bailliart

Publications and source records attributed to O Bailliart.

At least 37 records · Page 2Linked to original sources
PubMed1993

Relationship between birth weight and umbilical Doppler blood flow velocity waveforms during the third trimester of pregnancy.

OBJECTIVES: The Doppler ultrasound method for recording blood flow velocity waveforms in the fetal umbilical arteries is now widely used as an indicator of fetal well-being. This study was conducted to investigate the impact of umbilical placental resistance level on fetal growth development. METHODS: Maximal flow velocity waveforms were recorded from the umbilical artery in 108 pregnant women including 50 with normal pregnancies, 3 with previous death in utero, and 55 with moderate arterial hypertension corrected by resting only. All the newborn infants had a normal birth weight (BW between the 10th and the 90th percentile for the gestational age at birth). Doppler measurements were performed between 25 to 38 weeks of gestation. The placental resistance index (PRI) derived from blood flow velocity measurements was determined. RESULTS: Data were grouped in two-week intervals according to the age of gestation at Doppler examination. We found an inverse close relationship between BW and PRI which can be described by a linear function of PRI in each interval. BW increased with the decrease in PRI. CONCLUSIONS: Our findings suggest that umbilical placental resistance level determines fetal growth development and birth weight during pregnancies without placental insufficiency.

Birth Weight↗
PubMed1992

Comparative arterial antithrombotic activity of clopidogrel and acetyl salicylic acid in the pig.

We investigated the comparative antithrombotic properties of clopidogrel, an analogue of ticlopidine, and aspirin, using the Folts' model on femoral arteries in 22 pigs. On each animal, clopidogrel or aspirin were used to treat the thrombotic process on the left femoral artery and to prevent this process on the right femoral artery. Sequentially: an injury and stenosis were carried out on the left femoral artery; the thrombotic process was monitored with a Doppler during a 30-min observation period for cyclic flow reductions or permanent cessation of flow; after the first cyclic flow reduction occurred, clopidogrel (5 mg kg-1) or aspirin (2.5, 5, 100 mg kg-1) were injected intravenously; if cyclic flow reductions were abolished, epinephrine (0.4 micrograms kg-1 min-1) was injected to try to restore cyclic flow reductions and/or permanent cessation of flow; then injury and stenosis were applied on the right femoral artery. Before and after injection of clopidogrel or aspirin, ear immersion bleeding times and ex-vivo platelet aggregation were performed. Clopidogrel (n = 7) abolished cyclic flow reductions were efficiently prevented, even for two injuries. Basal bleeding time (5 min 28) was lengthened (> 15 min, 30 min after clopidogrel and remained prolonged even after 24 h). ADP-induced platelet aggregation was inhibited (more than 78%). Comparatively, aspirin had a moderate and no dose-dependent effect. Aspirin 2.5 mg kg-1 (n = 6) abolished cyclic flow reductions in 2 animals, CFR reoccurred spontaneously in one animal and epinephrine restored it in a second animal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Relationship between umbilical and fetal cerebral blood flow velocity waveforms and umbilical venous blood gases.

Nineteen women (mean +/- SD: 28 +/- 5 years) with small fetuses relative to gestational age (mean +/- SD: 32 +/- 2.2 weeks of gestation) were referred to our unit for cordocentesis for the determination of fetal karyotyping. Four of these 19 patients had small-for-gestational-age ultrasound-derived measurements under the third centile for gestational age. Fetal blood gases were measured in the umbilical vein. Umbilical artery and fetal internal carotid artery Doppler examinations were performed 15 min before cordocentesis. The results showed a progressive and proportional increase in umbilical artery resistance index with hypoxia (p < 0.001), hypercapnia (p < 0.025) and acidosis (p < 0.005). Moreover, the results showed a progressive and proportional decrease in fetal internal carotid artery resistance index with hypoxia (p < 0.01), hypercapnia (p < 0.01) and acidosis (p < 0.025). Fetal blood gases are therefore related to umbilical circulatory function and cerebral vasodilatation, suggesting fetal vascular redistribution.

Journal Article↗
PubMed1990

Does arterial PCO2 interfere with hypoxia in muscular metabolism in man?

To answer the question whether PCO2 affects the muscular metabolism, PO2, PCO2, pH, lactic acid concentration and hemoglobin were measured in the efferent muscular venous blood from common flexor digitorum, during forearm rhythmic exercise corresponding to VO2max. Exercise was carried out either in hypocapnic hypoxia i.e. in permanent high altitude residents and translocated lowlanders, or in hypercapnic hypoxia i.e. in chronic obstructive lung disease (COLD) patients. The results show that, during exercise: i) PO2 in muscular venous blood remains around 20 Torr in normoxia and hypocapnic hypoxia and even higher (25 torr) in COLD patients, despite low arterial PaO2, and ii) arterial and/or local PCO2 play a role in the control of the muscular blood flow. But we cannot conclude that a change in PaCO2 affects muscular metabolism itself, because lactic acid in the muscular venous blood, that we used to check this effect, is likely dependent on mechanisms other than anaerobic glycolysis, such as a change in lactic acid efflux from the myocytes. The increase in muscular venous PCO2 may enhance the myocyte permeability to lactic acid during exercise.

Acclimatization↗
PubMed1990

[Changes in the blood flow of the primary carotid and its branches during modifications of the O2 and CO2 composition of alveolar gas].

We measured common carotid blood flow using a range gated Doppler velocimeter, and internal and external blood velocities using a continuous Doppler in 20 lowlanders at sea level, under normal barometric pressure, in 10 subjects in an altitude chamber under a barometric pressure of 462 Torr (61.6 KPa) and then in 5 of them over a 3-weeks period at 3850 m of elevation (475 Torr = 63.3 KPa). The same measurements were also performed in 20 permanent residents at 3850 m. Common carotid blood flow was 15% higher in all subjects exposed to high altitude, due to a lowering in downstream resistances since systemic blood pressure did not change at high altitude. The increase in common carotid blood flow was the result of an immediate increase in internal carotid blood velocities observed in the altitude chamber as well as after the arrival at high altitude, but a few days later those velocities in the internal carotid artery declined to values similar to those observed at sea level. In the same time velocities in external carotid artery rose at high altitude, remained steadily elevated and the result is a permanent increase in common carotid blood flow at altitude. In all subjects we performed the same measurements, during an acute inhalation of gas mixtures to try to quantify the mechanisms controlling the changes in common carotid blood flow while changing gas inhalation. In the limits of the variations in PO2 (60 to 400 Torr) and in PCO2 (30 to 50 Torr) the stimulation by CO2 is twice more efficient than the O2 stimulation on vasomotion.

Adult↗
PubMed1990

Distribution of common carotid blood flow, measured by Doppler, in man at high altitude.

The aim of the work was to estimate the possible changes induced by high altitude in the distribution of the common carotid arterial blood flow towards the internal and external carotid arteries. Common carotid blood flow and internal and external blood velocities were measured in 20 lowlanders at sea level, in 5 of them over a 3-week period at 3800 m and in 20 permanent residents of this high altitude. Internal and external blood velocities were recorded with a continuous Doppler and blood flow was recorded by range-gated Doppler velocimeter. Common carotid blood flow was 15% higher in all subjects exposed to high altitude due to a lowering in downstream vascular resistance since systemic blood pressure did not change at high altitude. The increase of blood flow in the common carotid was the result of a rise mainly in the external carotid blood flow.

Acclimatization↗
PubMed1990

Periodic breathing and O2 saturation in relation to sleep stages at high altitude.

This study was designed to compare sleep organization at high altitude (HA) and sea level (SL) and to estimate the extent periodic breathing (PB) negatively influences arterial O2 saturation (SaO2). Six lowlanders were studied at SL and after 3 weeks spent at 3,800 m (La Paz, Bolivia). Three EEG leads, EOG, submental EMG, chest and abdominal motion, temperature of ventilated gas, and SaO2 were polygraphically recorded. Comparison of HA and SL data disclosed that: 1) Sleep organization was identical, with the same percentage of REM and stage 4. 2) PB (cycle length: 20 s; central apnea: 9 s) occurred in three subjects during all stages of sleep except REM (43-60% of total sleep). A periodic lowering in heart rate occurred during ventilatory oscillation. 3) During PB, SaO2 oscillated very regularly from 78-90%, which resulted in a mean SaO2 value calculated during oscillations similar to that of the non-periodic breathers. We conclude that lung O2 uptake during PB is preserved.

Altitude↗
PubMed1989

Anesthesia for creation of a forearm fistula in patients with endstage renal failure.

The effects of local infiltration anesthesia, brachial plexus blockade, isoflurane, or halothane anesthesia on blood flow through the brachial artery and through a newly created forearm arteriovenous fistula (AVF) were compared in 36 patients with endstage renal failure. Brachial artery blood flow was measured at two different times, before anesthesia and during anesthesia but before surgery, using a pulsed Doppler flowmeter. AVF flows were calculated from brachial, radial, and ulnar blood flows at the end of surgery, 2 h after surgery, and 3 and 10 days after the procedure. Mean arterial pressure was lower in patients receiving isoflurane or halothane than in those receiving local anesthesia or brachial plexus blockade (BPB). There was a significant increase in brachial artery blood flow following BPB (43.7 +/- 18.7 to 186.9 +/- 98.2 ml.min-1) during isoflurane anesthesia (46.2 +/- 15.9 to 153.1 +/- 80.5 ml.min-1) and during halothane anesthesia (49.9 +/- 24.1 to 97.6 +/- 62.1 ml.min-1). During anesthesia, the difference in brachial artery blood flow between patients in the BPB and halothane groups was significant. Local anesthesia failed to increase brachial artery blood flow (44.0 +/- 12.7 to 45.6 +/- 11.3 ml.min-1). In the immediate postoperative period, the AVF blood flow was lower in patients in the halothane group than in the other groups, but this difference was only significant when compared with BPB group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Effects of bisoprolol on local vascular resistance.

Changes in systolic and diastolic blood pressure, heart rate, arterial blood flow and vascular resistance in the arm and in the leg were investigated in 9 healthy volunteers (22-40 years) after oral dosing with bisoprolol 10 mg, propranolol 40 mg, and placebo in a randomized double-blind cross-over study. Arterial blood flow and vascular resistance were determined in brachial and femoral arteries with unimpeded circulation, after exclusion of the hand or foot by placing a tourniquet on the wrist or ankle, and during post-ischaemic hyperaemia. Distal arterial occlusion allows one to isolate a predominantly muscular circulation in the forearm or, to a lesser extent, in the leg. Both active drugs induced a significant fall in heart rate and systolic blood pressure versus placebo with no significant difference between the drugs. Brachial and femoral flow rates were reduced by both drugs probably due to a fall in cardiac output, but the two beta blockers produced different effects on vascular resistance: propranolol significantly increased brachial vascular resistance compared with placebo and bisoprolol, both during unimpeded circulation and during occlusion of the hand by a wrist tourniquet. Bisoprolol had no influence on brachial vascular resistance. Both drugs induced small increases in femoral vascular resistance. The different action on local vascular resistance in the brachial artery territory could be interpreted as the expression of the high beta 1 selectivity of bisoprolol leaving the vascular beta 2 receptors unopposed, whereas non-selective propranolol acts on both beta-adrenoceptor subtypes.

Adrenergic beta-Antagonists↗
PubMed1986

[Can respiratory tolerance to beta-blockers be predicted?].

Adverse effects on respiratory function is one of the main problems associated with the use of beta-adrenoceptor antagonists. Studies on this subject in healthy volunteers or patients with obstructive airway disease have been performed by measuring air flow at rest and after exercise, but no attention has been paid to the repercussions on pulmonary circulation. The lack of standardized protocol, the inhomogeneity of groups and the absence of long-term studies preclude objective comparisons between the different beta-adrenoceptor antagonists. On the whole, cardioselective beta-blockers are better tolerated than the others, but any classification based on the respiratory effects to cardiovascular effectiveness ratio is, for the moment, impossible to establish.

Adrenergic beta-Antagonists↗
PubMed1985

Quantitative Doppler blood flow measurement method and in vivo calibration.

Femoral blood flow (FBF) was measured in seven dogs, simultaneously with both an electromagnetic perivascular probe and a transcutaneous range gated Doppler velocimeter. Measurements were made in basal conditions and during intraarterial infusions of noradrenaline (10 to 400 ng . kg-1 . min-1) and isoprenaline (10 to 400 ng . kg-1 . min-1) thus allowing comparisons of ultrasonic (DBF) and electromagnetic (EMBF) blood flow at 91 different blood flow rates ranging from 5 to 300 cm3 . min-1. The linear regression line through the data of ultrasonic and electromagnetic simultaneous measurement was: DBF = 0.8 + 1.016 EMBF +/- 19.0 cm3 . min-1 with a highly significant correlation (r = 0.96, p less than 0.001) but there was a wide scattering about the mean. Errors in DBF were mainly due to positioning of the probe and determination of arterial diameter.

Animals↗
PubMed1981

[Hemodynamic study by pulsed ultrasonic velocimetry of axillo-femoral bypass].

Blood flow and the diameter of superficial vessels may be assessed non-invasively by pulsed doppler ultrasonography. Preoperative and follow-up studies were performed in 15 patients with Stage IV occlusive arterial disease undergoing axillo-femoral bypass operations. Blood flow and vessel diameter were measured in the femoral and humeral arteries and in the prosthetic bypass graft. There was no significant difference in flow in the humeral artery after bypass (35 cc/min). The femoral artery diameter was 0.36 cm and average flow was 47 +/- 30 cc/min. These results were compared to those obtained in 12 healthy controls (femoral artery diameter 0.62 +/- 0.05 cm; flow 126 cc/min) and in 29 patients with Stage II occlusive arterial disease with intermittent claudication (femoral artery diameter 0.47 +/- 0.08 cm; flow 87 cc/min). The average flow in the bypass one month after operation was 211 +/- 87 cc/min, falling to 124 +/- 53 cc/min at three months. These results are compared to those previously reported measured with electromagnetic flow counters at operation (273 cc/min). Finally, the internal diameter of the graft measured by ultrasound was compared with the true ex-vivo diameter and a constant difference of -2.12 +/- 0.94 mm was found. These results show the value of pulsed doppler ultrasonography in the assessment of peripheral blood flow for the follow-up of patients undergoing revascularisation procedures.

Aged↗
PubMedDate not supplied

Simultaneous ultrasonic measurement of carotid blood flow and intracerebral haemodynamics in man.

Common carotid blood flow and middle cerebral artery velocities were determined simultaneously by using a range gated Doppler velocimeter and transcranial apparatus in ten subjects. Middle cerebral artery velocities were used as an index of cerebral resistance. Different gas mixture concentrations were breathed in order to change cerebral haemodynamic conditions. In each condition there was a simultaneous modification of blood gases and cervicocerebral haemodynamics in common carotid blood flow and cerebral vascular resistance index. Carotid blood flow and the resistance index in middle cerebral artery changed also on opposite side. Acute hypercapnia in normoxia increases common carotid blood flow by 33% and simultaneously decreases cerebral resistance index by 11%. Normocapnic hyperoxia was associated with a fall in common carotid blood flow by 13% and with an increase in cerebral resistance index by 7%. There was a inter-subject statistically significant relation between common carotid blood flow and index of cerebral resistances (0.78 < r < 0.98). However there was an individual reactivity with large scatter when data from different subjects were pooled. Nevertheless the results provide evidence that changes in middle cerebral artery resistance indices are reflected by common carotid blood flow modifications.

Adult↗