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Biomedical subjects

B Teisseire

Publications and source records attributed to B Teisseire.

At least 37 records · Page 2Linked to original sources
PubMed1986

Laser angioplasty of arterial stenoses.

To establish the optimal conditions for recanalization of obstructed arteries without damage to vessel walls, an Nd-YAG laser coupled to a 0.2-mm-diameter optical fiber was used on obstructed human cadaver coronary and peripheral arteries and on popliteal arteries in amputated limbs. Vaporization of atheromatous plaques was consistently obtained with energy of 360-600 J and a diluted blood perfusate (3 g/100 ml hemoglobin) at a rate of 30 ml/min. The arterial wall was protected from thermal injury by inserting the optical fiber into an inflated balloon catheter and by cooling the system with the perfusate. Since recanalization of occluded arteries was consistently obtained without damage to the arterial wall or debris and thin and flexible optical fibers were easy to guide in the arteries, percutaneous transluminal Nd-YAG laser angioplasty was used in obstructed femoral and popliteal arteries in 12 patients. The first trials in man with Nd-YAG laser showed the method to be feasible, effective, and at low risk, although further studies are required to improve penetration of the obstruction and increase the diameter tunnel.

Angioplasty, Balloon↗
PubMed1986

[Arterial recanalization using the laser. A technic for the future?].

On the basis of two years' experience, a technique for the use of percutaneous endoluminal continuous emission Nd-YAG laser has been developed for arterial recanalisation. The effectiveness of this type of laser has been demonstrated in a large number of clots and atheromatous plaques, including calcified plaques. A balloon catheter gives a coaxial position of the fiber in center of the artery. Infusion of a blood solution containing 3 g of haemoglobin/100 ml at a rate of 20 ml/minute limits the thermal parietal lesions, improves the conditions of laser treatment and eliminates any risk of arterial perforation. No embolic debris is collected down-stream. Recanalisation of long arterial segments in amputated legs was performed prior to the human application. Ten patients have been treated with no mortality and virtually no morbidity. The narrowness of the reformed arterial lumina resulted in early re-thrombosis in the first 5 cases, requiring balloon modelling to ensure patency with a follow-up of 1 to 3 months in the 5 following patients.

Aged↗
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

Ascitic fluid pH in alcoholic cirrhosis: a reevaluation of its use in the diagnosis of spontaneous bacterial peritonitis.

An ascitic fluid pH less than or equal to 7.31 has been advanced as being the best index in the early diagnosis of spontaneous bacterial peritonitis in cirrhotic patients. In order to test the validity of this criteria, 55 patients with alcoholic cirrhosis and ascites were studied. In each patient, arterial blood and ascitic fluid samples were analysed for pH, PCO2, total CO2 and PO2, and the pH gradient between blood and ascites was calculated. White blood cell and polymorphonuclear cell counts were determined in ascitic fluid, and cultures of ascites were done under aerobic and anaerobic conditions. Twelve patients had a culture proven spontaneous bacterial peritonitis. Their mean ascitic fluid pH (+/- SD) was 7.38 +/- 0.09 (range 7.21-7.49) and differed significantly (p less than 0.05) from that found in patients without spontaneous bacterial peritonitis: 7.44 +/- 0.06 (range 7.34-7.6.3). A marked overlap was observed, however, between the two groups, and only three out of the 12 patients with spontaneous bacterial peritonitis had an ascitic fluid pH less than or equal to 7.31. The pH gradient was 0.10 +/- 0.08 (range -0.01 to +0.28) in the spontaneous bacterial peritonitis group, as compared with 0.02 +/- 0.04 (range -0.09 to +0.12) in the sterile group (p less than 0.01), but a marked overlap was also noted between the two groups. In the spontaneous bacterial peritonitis group, the polymorphonuclear count was 3588 +/- 3849/microliter (range 60-11 776) versus 41 +/- 138/microliter (range 0-813) in the sterile group (p less than 0.0001). All but one patient in the spontaneous bacterial peritonitis group and only two patients in the sterile group had over 250 polymorphonuclear/ microliter. Thus, in our experience, neither the ascitic fluid pH nor the pH gradient values accurately discriminated the individual patients with and without spontaneous bacterial peritonitis. A polymorphonuclear count less than 250/ microliter remained the best criteria for the diagnosis of spontaneous bacterial peritonitis in cirrhotic patients, before having the results of ascitic fluid cultures.

Adult↗
PubMed1985

Mechanical ventilation with 100% oxygen does not increase intrapulmonary shunt in patients with severe bacterial pneumonia.

Pure oxygen ventilation has been shown to increase the right to left shunt QS/QT in both normal and diseased lungs. Nitrogen absorption atelectasis, an explanation of the phenomenon, is likely to occur in lung units with low ventilation/perfusion ratio. In 11 patients with severe unilateral or bilateral bacterial pneumonia, we assessed the effects of increasing FlO2 from maintenance level (m = 0.44 +/- 0.11) to 1.0. Venous admixture (QVA/QT) was calculated using the O2 method, and the distribution of the VA/Q ratios were assessed with the 6 inert gas (IG) technique providing the distribution between the true shunt (QS/QT IG) and the low VA/Q units. Although a large part of perfusion was distributed preferentially to low VA/Q units, ranging from 2 to 43% of cardiac output, thus placing large zones of lung parenchyma at risk of absorption atelectasis, QVA/QT decreased from 31 +/- 13% to 25 +/- 10% and IG shunt did not increase after 30 min of O2 ventilation. In addition, QS/QT IG remained unaltered despite PVO2 increased from 32 to 43 mmHg, suggesting a poor level of hypoxic vasoconstriction in human bacterial pneumonia.

Bacterial Infections↗
PubMed1985

Influence of caloric intake on the respiratory mode during mandatory minute volume ventilation.

Mandatory minute volume ventilation has been proposed as a method for weaning patients from ventilators. The purpose of this study was to delineate the influence of caloric intake on spontaneous ventilation in patients receiving mandatory minute volume ventilation. While the value of such ventilation remained unchanged, eight patients were studied at the following three different levels of daily caloric intake: (1) level A, mean of 223 kcal/sq m; (2) level B, mean of 1,380 kcal/sq m; and (3) level C, mean of 2,100 kcal/sq m. We performed gas exchange measurements and a 24-hour recording of ventilation with a monitoring system providing distinction between spontaneous and mechanical cycles. We found that the ventilatory mode was markedly dependent upon the nutritional intake; the percentage of spontaneous ventilation over 24 hours increased from 11 +/- 7 percent (+/- SE) during diet A to 50 +/- 9 percent during diet B and 79 +/- 8 percent during diet C. This increment paralleled the increase in production of carbon dioxide with caloric intake. We suggest therefore that the patient's ability to breathe spontaneously when receiving mandatory minute volume ventilation should be interpreted according to caloric intake.

Aged↗
PubMed1985

Hypoxemia in acute pulmonary embolism.

Most patients with severe, acute pulmonary embolism (PE) have arterial hypoxemia. To further define the respective roles of ventilation to perfusion (VA/Q) mismatch and intrapulmonary shunt in the mechanism of hypoxemia, we used both right heart catheterization and the six inert gas elimination technique in seven patients with severe, acute PE (mean vascular obstruction, 55 percent) and hypoxemia (mean PaO2, 67 +/- 11 mm Hg). None had previous cardiopulmonary disease, and all were studied within the first ten days of initial symptoms. Increased calculated venous admixture (mean QVA/QT 16.6 +/- 5.1 percent) was present in all patients. The relative contributions of VA/Q mismatching and shunt to this venous admixture varied, however, according to pulmonary radiographic abnormalities and the time elapsed from initial symptoms to the gas exchange study. Although all patients had some degree of VA/Q mismatch, the two patients studied early (ie, less than 48 hours following acute PE) had normal chest x-ray film findings and no significant shunt; VA/Q mismatching accounted for most of the hypoxemia. In the others a shunt (3 to 17 percent of cardiac output) was recorded along with radiographic evidence of atelectasis or infiltrates and accounted for most of the venous admixture in one. In all patients, a low mixed venous oxygen tension (27 +/- 5 mm Hg) additionally contributed to the hypoxemia. Our findings suggest that the initial hypoxemia of acute PE is caused by an altered distribution of ventilation to perfusion. Intrapulmonary shunting contributes significantly to hypoxemia only when atelectasis or another cause of lung volume loss develops.

Acute Disease↗
PubMed1985

[Arterial disobliteration by the laser].

In order to determine the optimal conditions for disobliteration of occluded arteries without damaging the arterial wall, the effects of a Nd-YAG laser connected to a 0.2 mm diameter fibre optic system were studied on post-mortem coronary arteries and popliteal and tibial arteries of amputated limbs. Vaporisation of atheromatous plaques was consistently obtained with energies of 300 to 600 joules associated with perfusion of the vessel with dilated blood (3 g/100 ml of haemoglobin) at a flow rate of 20 ml/min. Protection of the arterial wall was ensured by introducing the fibre aortic system through a balloon catheter and by cooling with the perfusion liquid. The reproducibity of these results in the absence of major arterial wall damage, and the facility of manipulation of the fibre optic system due to its flexibility and narrow diameter, encouraged us to use this method clinically. The first three applications on peripheral arteries (femoral and popliteal arteries) confirmed that this method of arterial disobliteration can be used with a certain degree of efficacy with only a slight risk of arterial perforation. Further studies are essential to improve the degree of laser penetration of the arterial obstruction and to increase the diameter of the tunnel of recanalisation.

Arterial Occlusive Diseases↗
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↗
PubMed1984

[Acute respiratory distress syndrome in the adult. Distribution of the ventilation-perfusion ratio].

Hypoxemia in the acute respiratory distress syndrome may be due to a variety of causes: trùe pulmonary shunt, decreased ventilation/perfusion ratios, impaired diffusion and/or fall of mixed venous oxygen. In order to sort out these different tension mechanisms, 18 patients with acute respiratory distress syndrome were explored by the inert gas method. In 6 of them hypoxemia was due to a true shunt (35 +/- 10%). The remaining 12 patients also had a true shunt (26.5 +/- 9.5%), but 4.5% of the cardiac output was distributed to areas with a ventilation/perfusion ratio between 0.1 and 0.005. Thus, in these 18 patients with acute respiratory distress, hypoxemia could be explained essentially by a true shunt.

Adult↗