References of "Fossion, Anny"
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See detailEffects of Peep on Systemic Venous Capacitance
Lambermont, Bernard ULg; Detry, Olivier ULg; D'Orio, Vincenzo ULg et al

in Archives of Physiology & Biochemistry (1998), 105(4), 373-8

The aim of the present study was to determine effects of positive end expiratory pressure (PEEP) application on peripheral venous capacitance and relate them to concomitant central hemodynamic ... [more ▼]

The aim of the present study was to determine effects of positive end expiratory pressure (PEEP) application on peripheral venous capacitance and relate them to concomitant central hemodynamic disturbances. The venous volume-pressure (V/P) relationships were studied in 6 intact anesthetized pigs to describe the effects of PEEP on systemic venous compliance (computed as the slope of the V/P relationship) and unstressed volume (referred to as the extrapolated volume intercept). Cardiac volumes as well as partitioning of circulating blood volume between central (ITBV) and peripheral (PBV) compartments were assessed by thermo-dye dilution techniques. During a 15 cm H2O PEEP application, venous compliance was reduced by 48%, while unstressed volume was increased by 25% and peripheral blood pooling increased from 63 to 74%. As a result, left heart and right ventricular end diastolic volumes were decreased by 8% and by 44%, respectively. It is concluded that increased venous unstressed volume and reduced compliance depicted the distension of the venous tree secondary to PEEP which acted as an impediment to venous return. As a consequence, cardiac output was reduced because of decreased preload. [less ▲]

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See detailAnalysis of Endotoxin Effects on Pulmonary Circulation in Terms of Pressure-Flow Characteristics
D'Orio, Vincenzo ULg; Fatemi, M.; Marnette, J. M. et al

in Circulatory Shock (1993), 39(4), 285-92

The purpose of the present work was to explore the hypothesis that pulmonary vasoconstriction secondary to endotoxin insult results mainly from an increase in the critical closing pressure of the ... [more ▼]

The purpose of the present work was to explore the hypothesis that pulmonary vasoconstriction secondary to endotoxin insult results mainly from an increase in the critical closing pressure of the pulmonary vessels. Specifically, we reasoned that in the face of a Starling resistor located between pulmonary arteries and left atrium, upstream transmission of increased left atrial pressure (Pla) would be inversely related to the level of the pressure intercept (Pi) obtained by extrapolation from the linear pulmonary arterial pressure (Ppa)--flow (Q degrees) plot. Six dogs (group E) were infused with Escherichia coli endotoxin (0.25 microgram/kg/min) for 2 hr, whereas six additional dogs (group C) served as control. During baseline conditions, Pi approximated LAP in both groups. In group C dogs, increasing LAP at constant Q degrees led to a proportional augmentation of Ppa. In group E dogs, endotoxin resulted in a shift of the Ppa-Q relationships to higher pressures due to both increases in Pi and slope. In addition, changes in Pla over the same range as in control dogs affected Ppa only at the highest levels of Pla. We conclude that endotoxin insult increases the critical closing pressure that exceeds Pla and induces the occurrence of a Starling resistor responsible for the production of an effective vascular waterfall. [less ▲]

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See detailModelling the Arterial Wall by Finite Elements
Mosora, F.; Harmant, A.; Hallet, Claude ULg et al

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1993), 101(3, May-Jun), 185-91

The mechanical behaviour of the arterial wall was determined theoretically utilizing some parameters of blood flow measured in vivo. Continuous experimental measurements of pressure and diameter were ... [more ▼]

The mechanical behaviour of the arterial wall was determined theoretically utilizing some parameters of blood flow measured in vivo. Continuous experimental measurements of pressure and diameter were recorded in anesthetized dogs on the thoracic ascending and midabdominal aorta. The pressure was measured by using a catheter, and the diameter firstly, at the same site, by a plethysmograph with mercury gauge and secondly, by a sonomicrometer with ferroelectric ceramic transducers. The unstressed radius and thickness were measured at the end of each experiment in situ. Considering that the viscous component is not important relatively to the nonlinear component of the elasticity and utilizing several equations for Young modulus calculation (thick and thin wall circular cylindrical tube formulas and Bergel's equation) the following values were obtained for this parameter: 0.6 MPa-2 MPa in midabdominal aorta and 2 MPa-6.5 MPa in thoracic ascending aorta. The behaviour of the aorta wall was modelled considering an elastic law and using the finite element program "Lagamine" working in large deformations. The discretized equilibrium equations are non-linear and a unique axi-symmetric, iso-parametric element of 1 cm in length with 8 knots was used for this bi-dimensional problem. The theoretical estimation of radius vessel, utilizing a constant 5 MPa Young modulus and also a variable one, are in good agreement with the experimental results, showing that this finite element model can be applied to study mechanical properties of the arteries in physiological and pathological conditions. [less ▲]

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See detailIdentification of Three-Element Windkessel Model: Comparison of Time and Frequency Domain Techniques
Pochet, T.; Gérard, Paul ULg; Marnette, J. M. et al

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1992), 100(3, May-Jun), 295-301

The problem of the parameter identification of the three-element windkessel model is studied. Minimization by least-square technique--LSQ--in time domain and frequential techniques--FFT--are compared ... [more ▼]

The problem of the parameter identification of the three-element windkessel model is studied. Minimization by least-square technique--LSQ--in time domain and frequential techniques--FFT--are compared. Continuous pressure and flow curves were recorded in the proximal aorta of an open chest dog. Comparison shows very high correlations between the parameter estimations obtained by LSQ and FFT methods. However, systematic differences appear between the calculated values, but do not seem to endanger physiological interpretation of the results. [less ▲]

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See detailEffets du blocage des recepteurs beta-adrenergiques sur l'hyperlactacidemie induite par des exercices d'intensites differentes.
Scheen, André ULg; Camus, G.; Fossion, Anny ULg

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1991), 99(4), 331-4

The effects of beta-adrenergic blockade on the exercise-induced hyperlactatemia (Lap) have been studied in 31 adult male subjects [age: 25 +/- 1 years; body weight: 69 +/- 1 kg; VO2max: 54 +/- 1 ml O2.kg ... [more ▼]

The effects of beta-adrenergic blockade on the exercise-induced hyperlactatemia (Lap) have been studied in 31 adult male subjects [age: 25 +/- 1 years; body weight: 69 +/- 1 kg; VO2max: 54 +/- 1 ml O2.kg-1.min-1 (mean values +/- SEM)] randomly divided in 3 groups. All exercises were performed on a 10% inclined treadmill. In group 1 (n = 11), the subjects were walking during 20 minutes at 5 km.h-1 (55.6 +/- 1.4% VO2max). In group 2 (n = 10), they were running during 9 minutes at 8 km.h-1 (79.4 + 1.5% VO2max). The subjects of the third group (n = 10) were submitted to a 4 minutes run at 9.5 km.h-1 92 +/- 1.6% VO2max). These exercises were performed 1 hour after ingestion of a placebo or a single dose of 40 mg propranolol, in a double-blind randomized order. Blood samples were drawn at regular time intervals from an antecubital vein. Exercise tachycardia was reduced by about 20% (P less than 0.001) by propranolol in each group. Lap was significantly reduced by 15% by propranolol (P less than 0.005) at the lowest exercise intensity (55.6% VO2max), remained unchanged at 79.4% VO2max and was significantly enhanced by 16% during the recovery period following the run at 92% VO2max. These results clearly showed that the effects of acute beta-adrenergic blockade on Lap depend on exercise intensity. [less ▲]

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See detailContribution of Peripheral Blood Pooling to Central Hemodynamic Disturbances During Endotoxin Insult in Intact Dogs
D'Orio, Vincenzo ULg; Wahlen, C.; Naldi, Marco ULg et al

in Critical Care Medicine (1989), 17(12), 1314-9

The aim of the present study was to determine possible effects of Escherichia coli endotoxin on peripheral vascular compliance and relate them to concomitant central hemodynamic disturbances. Endotoxin ... [more ▼]

The aim of the present study was to determine possible effects of Escherichia coli endotoxin on peripheral vascular compliance and relate them to concomitant central hemodynamic disturbances. Endotoxin was infused at 0.25 micrograms/kg.min during 2 h in six anesthetized dogs, while six additional animals served as controls. Vascular compliance of the systemic circulation was calculated in intact animals from the changes in CVP after known changes in systemic blood volume. In control dogs, vascular compliance averaged 2.3 ml/mm Hg.kg body weight. During slow endotoxin infusion, cardiovascular effects were measurable only after a certain period of time had elapsed from the start of endotoxin insult and consisted of hypotension associated with systemic vasodilation. Systemic BP decreased gradually from 124 to 68 mm Hg while vascular compliance was finally increased by 100%, when compared to control values. This latter rise was responsible for a reduction in the cardiac preloads. Pulmonary wedge pressure and CVP were decreased from 7.1 to 3.4 and from 4.5 to 2.6 mm Hg, respectively. However, parallel to the decrease in left ventricular preload, endotoxin induced a progressive decrease in left ventricular afterload. Because of the balance in ventricular loading, cardiac output remained almost unchanged. After volume loading (dextran 30 ml/kg), cardiac output was remarkably increased from 3.28 to 6.24 L/min.m2 while peripheral vasodilation was not affected by this maneuver. It is concluded that low dose endotoxin infusion induces in dogs a hemodynamic pattern similar to human sepsis. The left ventricular loading changes are related to an enhanced systemic vascular compliance from 2.3 to 4.5 ml/mm Hg.kg. High flow shock state is encountered provided peripheral blood pooling is compensated by adequate volume replacement. [less ▲]

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