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Biomedical subjects

M Duruble

Publications and source records attributed to M Duruble.

At least 19 recordsLinked to original sources
PubMed1991

[Distal obliterating arteriopathy of the lower limbs in a systemic disease. Treatment with normovolemic hemodilution. [Report of one case]].

The authors report on a 31 year old man with a generalised illness consisting of: buccal aphthous ulcers, distal arteriopathy, multiform cutaneous lesions (necrotising vasculitis, folliculitis, nodules), hypersensitivity at the site of puncture, Raynaud's syndrome and superficial venous thromboses. After the failure of various therapies (calcium heparin, ticlopidine, colchicine, corticoids, immunostimulants), the patient was successfully treated by normovolemic haemodilution on 20 occasions, obtaining each time healing of the skin lesions within 2 to 4 weeks.

Adult↗
PubMed1986

[Long-term normovolemic hemodilution in refractory postphlebitic ulcers].

Thrombo-embolic complications are still amongst the most serious encountered in surgery and in certain medical afflictions, despite the different forms of prophylaxis, and in particular subcutaneous heparin. Thus, in 1983, an investigation by Salleras in Barcelona based on 37,400 cases, assessed the incidence of these complications after surgery at a rate of 2.5%. That is why post-phlebitic syndromes, the results of late diagnosis at the acute stage and/or inappropriate treatment, are disorders which are still very widespread, chronic, and more or less incapacitating. At the root of tissue modifications and trophic disorders which are seen in the post-phlebitic illness, a state of venous stasis at the periphery of the limbs is very often encountered; it depends on the following processes: the obstruction of a large venous collector (obstructive syndrome), the size of the stasis depending on the functional value of the anastomotic channels; the insufficiency of the superficial network; orthostatic reflux in the repermeabilized deep veins whose valvular system has broken down. The main trophic complications are: oedema, hypodermatitis and leg ulceration, which is the most formidable complication and which still occurs very frequently. Most post-phlebitic ulcers heal after a well-executed phlebological treatment on an ambulatory basis. A certain number of these ulcers prove, however, to respond badly to ambulatory treatment; they are called resistant post-phlebitic ulcers. By definition, they are difficult to cure; however, it has recently been apparent that the classical treatments associated with long-term isovolaemic haemodilution are more effective and enable healing to take place by treating the venous stasis and the increased blood viscosity.

Adult↗
PubMed1985

Transient responses of coronary flow in the blood-perfused isolated rat heart submitted to changes in oxygen content.

This study examines the transient response of coronary blood flow to acute changes in O2 content at normal and high arterial PO2 (Pa, O2) in the blood-perfused, working isolated rat heart. The perfusion system used in this study presents the following advantages: it eliminates the gas/blood interface, includes a peripheral circulation for control of pre-load and after-load, and allows for rapid change of perfusates and continuous recording of aortic and coronary blood flow. With this system the isolated rat heart is capable of stable haemodynamic performance for periods in excess of 4 h. A sudden decrease in O2 content from 0.147 to 0.067 11(-11) at constant Pa,O2 (133 mmHg; n = 15) was associated with a marked increase in coronary blood flow (QCOR). This increase showed two phases: a rapid phase which reached 200% of the control value in 20 s, followed by a slow phase (235% in 90 s). When the same decrease in O2 content (0.135 to 0.057 11(-1] was associated with an increase in Pa, O2 (n = 22; 143 to 412 mmHg), the response of QCOR was limited both in amplitude (175% rather than 235%) and in rate of onset (response time of 15.6 instead of 9.2 s). These results are consistent with the majority of currently popular hypotheses regarding control of QCOR including the adenosine hypothesis and that of vessel wall PO2 being a direct mediator. The time course of changes in coronary vascular resistance, with a Pa, O2-dependent rapid phase, suggests the simultaneous function of the two mechanisms.

Animals↗
PubMed1985

Hemodynamic and metabolic responses of the working heart in relation to the oxygen carrying capacity of the perfusion medium.

Hemodynamic and metabolic adaptations of isolated working heart perfused alternatively with normal or low oxygen carrying capacity medium were studied in an experimental model. A step change in arterial oxygen content (1.75 to 15.3 ml O2/100 ml) was followed by a decrease in coronary flow, an increase in aortic flow, external work, myocardial oxygen consumption and efficiency, respectively. Metabolic investigations (steady state values) showed the activities of both glycolysis and the Krebs cycle to increase with the oxygen carrying capacity of the perfusion medium. Within the limits of these aerobic conditions, most of the cardiac changes were reversible. The use of reconstituted blood provides physiological conditions of oxygenation, allows a dynamic equilibrium between oxygen supply and oxygen requirements and maintains a near physiological regulation between cardiac dynamic and metabolic functions. These conclusions stress the importance of optimal O2 carrying capacity of perfusion medium in metabolic studies on isolated working heart.

Aerobiosis↗
PubMed1985

Effects of changes in hematocrit on red cell flows at capillary bifurcations.

A theoretical study was developed to evaluate effects of changes in hematocrit on red cell flow partitioning at narrow capillary bifurcations of unequal diameters. Non-Newtonian blood viscosity and non-linear relationships between blood and red cell flows at capillary bifurcations are taken into account. Results suggest that heterogeneity of diameters is a determinant of red cell and blood flows heterogeneity not only due to its influence on geometrical resistance but also as a result of its influence on capillary viscosity. Lowering hematocrit reduces differences in viscosities between the two branches. Then more homogeneous red cell flows are induced. Considering three possible relationships for entering blood flow vs. entering discharge hematocrit, the present study stresses that changes in red cell flow for individual capillaries are not parallel to changes in entering red cell flow. Therefore discussion on effects of hemodilution have to take into account not only red cell flow or oxygen arriving to an organ, but also changes in distribution of capillary flows induced by rheological changes due to lower hematocrit.

Blood Viscosity↗
PubMed1982

[Transcapillary fluid exchanges. A program in Basic].

Transcapillary fluid exchanges are analysed with the Wiederhielm's model programmed in this study in Basic language. The physiological variable which are taken in account are: arterial and venous capillary pressures, interstitial pressure and the colloid osmotic pressure of plasma and tissue proteins. This model shows the relationship between filtration, reabsorption, plasma leakage and the lymph flow. Edema resulting from venous and lymphatic obstruction or from a decrease in plasma oncotic pressure are simulated.

Blood Pressure↗
PubMed1979

Effect of an increase in HbO2 affinity on the calculated capillary recruitment of an isolated rat heart.

The effect of an increase in hemoglobin O2 affinity on myocardial O2 delivery was studied in a blood perfused working rat heart preparation. In a first series of experiments P50 (PO2 for which saturation is 50%) was lowered by use of carbon monoxide. The heart was alternatively perfused with the blood sample of P50 = 32 mm Hg and the blood sample of P50 = 17 mm Hg. O2 capacity of both samples was kept the same by appropriate hemodilution. In a second serie of experiments change of P50 was obtained by the use of adult human erythrocytes containing hemoglobin creteil with a P50 of 13.6 mm Hg. As P50 decreased from 25 to 10 mm Hg, coronary sinus PO2 (PcsO2) diminished from 26 +/- 2 to 18 +/- 2 mm Hg (-29 +/- 2%), coronary sinus O2 content (CcsO2) increased by 15 +/- 3%, myocardial oxygen consumption did not change significantly. The percentage of increase of coronary flow was 23 +/- 4%. Analysis of these results with a simple mathematical model of O2 delivery suggest that increase in HbO2 affinity is corrected by a simultaneous increase in coronary flow and capillary recruitment.

Animals↗
PubMed1979

[Theoretical, experimental and clinical effects of variations in hematocrit during hemodilution].

By decreasing both viscosity and maximum oxygen capacity, a fall in hematocrit has two opposing effects on oxygen transport. The resultant of these effects was studied using a mathematical model representing the circulatory system and the oxygen transport system. This simulation showed that hemodilution decreased mean aortic pressure, increased central venous pressure and cardiac output. Oxygen supply to the tissues was maximum at a hematocrit of 30 p. cent. Blood volume was an essential parameter. These theoretical concepts of an optimum hematocrit of 30 p. cent were confirmed in the isolated rat heart perfused by blood with varying hematocrits. A clinical study in general surgery involving 307 patients where the hematocrit was reduced to below 32 p. cent by replacing blood loss by Ringer lactate or a fluid gelatin type solution, showed the good tolerance of normovolaemic hemodilution when used carefully, and its value in the prevention of post-operative thrombo-embolic disease.

Adult↗
PubMed1976

Blood-perfused working isolated rat heart.

We describe a method for perfusion of a working isolated rat heart with washed erythrocytes suspended in a Krebs-Henseleit bicarbonate buffer containing bovine albumin (fraction V). With washed pig red cells, as hematocrit was varied between 0 and 40%, coronary flow (CF), aortic flow (AF), external work (W), and myocardial oxygen consumption (MVO2) were measured. Hemodynamic data at a hematocrit of 30% (CF = 5.4 +/- 0.7 ml/min per g, AF = 75 +/- 8 ml/min per g) were identical with those reported for the intact animal. Coronary sinus PO2 was highest with a red cell-free perfusate suggesting that coronary flow is partially shunted. Human red cells obtained from banked blood, were tried also with success. With careful filtration, the preparation is stable for 2 h and well suited for study of the dynamics of myocardial oxygen delivery.

Animals↗