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Biomedical subjects

A Margairaz

Publications and source records attributed to A Margairaz.

At least 19 recordsLinked to original sources
PubMed1991

Comparison of the effects of intravenous almitrine and positive end-expiratory pressure on pulmonary gas exchange in adult respiratory distress syndrome.

The effects of almitrine on pulmonary gas exchange and haemodynamics were compared to those of positive end-expiratory pressure (PEEP) in 10 patients with a severe adult respiratory distress syndrome (ARDS) who required continuous mechanical ventilation. Haemodynamic and gas exchange measurements were made before and after 30 min of PEEP at a level of 10 cmH2O, then 30 min later, before and at the end of the intravenous infusion of almitrine at a dose of 0.25 mg.kg-1 in 30 min. There was no significant difference between baseline gas exchange and haemodynamic parameters. PEEP and almitrine increased Pao (p = 0.001) from 10.9 to 12.6 kPa and from 10.6 to 12.6 kPa (1 kPa = 7.5 mmHg), respectively, and ratio of venous admixture to total blood flow (Qs/Qt) decreased (p less than 0.001) from 34 to 29% and from 33 to 29%, respectively, the effects of PEEP and almitrine being not significantly different. Neither PEEP nor almitrine caused a significant change in arterial carbon dioxide tension (PaCO2). The haemodynamic parameters did not change significantly with almitrine, whereas mean systemic arterial pressure decreased from 85.4 to 81.1 mmHg (p less than 0.05) with PEEP. These results are consistent with the hypothesis that both treatments improve ventilation/perfusion (VA/Q) distributions, by an increase in functional residual capacity in the case of PEEP and a redistribution of pulmonary perfusion in the case of almitrine.

Adult↗
PubMed1987

Inspiratory impairment in right ventricular performance during acute asthma.

Right ventricular function was investigated in seven asthmatic patients during an acute attack, using simultaneous bedside right heart catheterization and two-dimensional echocardiography (2DE). Hemodynamic and echocardiographic data were compared during four successive periods of the respiratory cycle: inspiration, early expiration, mid-expiration, and late expiration. During inspiration, 2DE showed a significant increase in right ventricular area at both end-systole and end-diastole. This inspiratory right ventricular enlargement coexisted with a significant reduction in 2DE stroke area and pulmonary artery pulse pressure suggesting an inspiratory reduction in right ventricular stroke output. A transient depression of right ventricular function during deep inspiratory effort in asthma was thus strongly suggested. The negative pressure surrounding the right ventricle at inspiration is advocated as the causative factor enabling reduction in the hydraulic force effecting right ventricular ejection. The highly negative pleural pressure probably holds the right ventricular free wall and restrains its systolic inward motion, as suggested by the finding of a concomitant inspiratory reduction in right ventricular developed pressure and 2DE fractional area contraction.

Acute Disease↗
PubMed1985

Two-dimensional echocardiographic evaluation of right ventricular size and contractility in acute respiratory failure.

Right ventricular size and contractility were evaluated using two-dimensional echocardiography during the first days of respiratory support in 23 patients requiring mechanical ventilation for acute respiratory failure. Nine patients had normal echocardiographic right ventricular function, and nine other patients had a slightly enlarged right ventricle with normal systolic function. The remaining five patients had a severely enlarged right ventricle with abnormal contractile pattern. In these five patients, two-dimensional echocardiography also showed a reduction in left ventricular size suggesting detrimental ventricular interdependence. All 23 patients had normal left ventricular systolic function by two-dimensional echocardiography.

Acute Disease↗
PubMed1985

Dobutamine: a hemodynamic evaluation in pulmonary embolism shock.

Intravenous dobutamine was used in ten patients requiring aggressive therapy for massive pulmonary embolism with circulatory failure. Except in one patient who rapidly died, a 30-min dobutamine infusion (8.3 +/- 2.7 micrograms/kg . min) increased both cardiac index (from 1.7 +/- 0.4 to 2.3 +/- 0.6 L/min . m2, p less than .001) and stroke index (from 16.6 +/- 6.7 to 21 +/- 5 ml/m2, p less than .01), and also reduced pulmonary vascular resistance. Additional hemodynamic improvement was observed until weaning from dobutamine, which was successfully completed 3.3 +/- 0.9 days after the start of infusion.

Adult↗
PubMed1985

Right ventricular volumes by thermodilution in the adult respiratory distress syndrome. A comparative study using two-dimensional echocardiography as a reference method.

Measurements of right ventricular ejection fraction and volumes were obtained at bedside by the thermodilution method performed with a fast-response balloon-tipped thermistor in a group of 18 patients undergoing respiratory therapy for the adult respiratory distress syndrome (ARDS). These measurements were compared with right ventricular dimensions simultaneously obtained with two-dimensional echocardiography. A significant correlation was found between right ventricular ejection fraction by thermodilution and two-dimensional echocardiographic fractional area contraction (r = 0.74; p less than 0.001), between right ventricular end-diastolic volume by thermodilution and two-dimensional echocardiographic end-diastolic area (r = 0.70; p less than 0.001), and between right ventricular end-systolic volume by thermodilution and two-dimensional echocardiographic end-systolic area (r = 0.78; p less than 0.001). Right ventricular end-diastolic pressure, a commonly used index of right ventricular preload, did not correlate with two-dimensional echocardiographic end-diastolic area. In conclusion, the thermodilution method allowed reliable measurements of right ventricular ejection fraction and volumes at bedside in critically ill patients. Appraisal of right ventricular end-diastolic volume by this method appeared to be a better predictor of right ventricular preload than were the measurements of pressure.

Adolescent↗
PubMed1984

[Acute right ventricular failure. Treatment with dobutamine].

Acute right ventricular failure is commonly observed during respiratory intensive care, particularly in patients suffering from massive pulmonary embolism, chronic obstructive pulmonary disease or adult respiratory distress syndrome. The haemodynamic effects of a continuous dobutamine infusion at the rate of 9.4 +/- 3.7 micrograms/kg/min were assessed in a group of 15 patients with acute and isolated right ventricular failure, as evidenced by haemodynamic and two dimensional echocardiographic measurements. This inotropic agent induced at 37% increase in mean cardiac index and a 25% increase in mean stroke index, with only a 10% increase in mean heart rate. Moreover, measurement of the right ventricular ejection fraction by a thermal dilution technique performed in 10 patients demonstrated that dobutamine consistently and significantly increased right ventricular systolic function and also significantly reduced right ventricular end-diastolic tension. In conclusion, it appeared that dobutamine was able to improve circulatory status in patients with acute right heart failure or various origins.

Acute Disease↗
PubMed1984

Circulatory failure in acute pulmonary embolism.

Circulatory failure occurs in about 10% of patients with pulmonary embolism, resulting from a massive obstruction of the pulmonary arterial bed. Hemodynamic and respiratory features are well established; they involve precapillary pulmonary hypertension, low cardiac output state, elevated filling pressure for the right ventricle, and venous admixture. More recently, two-dimensional echocardiography permitted the visualization of pulmonary artery and right heart enlargement, reduced right ventricular ejection fraction, and tricuspid regurgitation. Evaluated by this latter means, left ventricular systolic function appeared unchanged, but diastolic function might be reduced by septal bulging.

Cardiac Output, Low↗
PubMed1984

Two-dimensional echocardiographic demonstration of acute myocardial depression in septic shock.

A 50-yr-old woman exhibiting streptococcal neck cellulitis developed severe septic shock with low cardiac output, which was reversed by infusion of dopamine plus dobutamine. Two-dimensional echocardiography performed at the bedside demonstrated severe myocardial failure. The patient's condition remained dependent on inotropic drug support for 2 days and ultimately improved. Two-dimensional echocardiography repeated on the fourth day corroborated the disappearance of transient myocardial failure.

Cardiac Output, Low↗
PubMed1982

[Outcome of the adult acute respiratory distress syndrome. Predictive value of a severity index calculated from arterial oxygenation (author's transl)].

A retrospective study was carried out a group of 50 adult patients who had presented with acute respiratory distress syndrome and had all been treated by mechanically controlled ventilation with positive end-expiratory pressure (PEEP). The predictive value of the so-called "severity index" was tested. This index, which is used from the second day of treatment onward to predict with strong probability whether the lung lesions will subside or develop, is obtained from the PaO2 after corrections taking into account the FiO2 and the PEEP level. The study also supplied information on the outcome of lung lesions which may result in one of four possible courses of about equal frequency: the patient may either die or be cured rapidly after less than a week of assisted ventilation, or he may die at a later date or be cured slowly after more than a week of assisted ventilation.

Female↗
PubMed1982

Hemodialysis in septic patients: improvements in tolerance of fluid removal with concentrated albumin as the priming fluid.

Hemodynamic function and volume of ultrafiltration (UF) during hemodialysis were studied in 8 patients with anuric acute renal failure (ARF) and severe sepsis. Patients were alternatively dialyzed with a saline priming (every 2 days) and with a 17.5% albumin priming. Hypovolemia, as indirectly reflected by reduced left ventricular filling pressure, decreased cardiac output (CO), and decline in mean systemic arterial pressure (MAP), was observed during the hemodialysis procedure using saline as the first prime. Hemodialysis was tolerated better after concentrated albumin priming; left ventricular filling pressure increased during the 1st h of dialysis, whereas CO and MAP remained close to that of control values. Furthermore, UF could be increased progressively without major hemodynamic consequences in the patients who received a concentrated albumin priming; moreover, larger volumes of fluid were removed.

Acute Kidney Injury↗
PubMed1981

Influence of positive end-expiratory pressure on left ventricular performance.

Although left ventricular dysfunction is common during ventilatory support with positive end-expiratory pressure (PEEP), the mechanism of this disorder remains unclear. In 10 patients with the adult respiratory-distress syndrome we studied the effects of a stepwise increase in PEEP from 0.to 30 cm H2O on left ventricular output, intracardiac transmural pressures, and two-dimensional echocardiographic measurements of left ventricular cross-sectional area at end-systole and at end-diastole. Increasing PEEP was associated with progressive declines in cardiac output, mean blood pressure, and left ventricular dimensions and with equalization of right and left ventricular filling pressures. The radius of septal curvature decreased at both end-diastole and end-systole, implying a leftward shift of the interventricular septum. At the highest PEEP, blood-volume expansion did not restore cardiac output, although left ventricular transmural filling pressures had returned to base-line values. We conclude that decreased cardiac output during PEEP is mediated by a leftward displacement of the interventricular septum, which restricts left ventricular filling.

Blood Pressure↗
PubMed1981

Controlled ventilation with best positive end-expiratory pressure (PEEP) and high level PEEP in acute respiratory failure (ARF).

We assessed hemodynamics, total lung and chest wall compliance (CT) and gas exchange using two different levels of PEEP during controlled ventilation in two different groups of patients with ARF; in the first group (Group 1, 12 patients) chest X-Rays showed a symmetrical pattern of bilateral alveolar infiltrates; in the second group (Group 2, 5 patients) chest X-Ray showed a asymmetrical pattern with unilateral lobar consolidation. A first level of PEEP (best PEEP = 9 +/- 3 cm H2O) produced an improvement in CT and in gas exchange with a slight decrease in cardiac index in both groups; but improvement in PaO2 (from 64 +/-33 to 122 +/- 76 torr, p less than 0.001 in Group 1, and from 76 +/- 39 to 91 +/- 33 torr, p less than 0.05 in Group 2) and decrease in QS/QT were not as well marked in Group 2 as i Group 1. A second level of PEEP (high level PEEP: 20 +/- 4 cm H2O) produced a sharp decrease in CT and required hemodynamic support in each case (blood volume expansion with or without Dopamine infusion) to maintain cardiac index within a normal range. In Group 1 this high level PEEP produced a greater improvement in gas exchange (PaO2 increased from 122 +/- 76 to 194 +/- 76, p less than 0.01) but in Group 2 it had a deleterious effect, producing a decrease in PaO2 (from 91 +/- 33 to 76 +/- 41 torr, p less than 0.05), and an increase in QS/QT; with this higher PEEP we also noted an increase of alveolar dead space in Group 2. This study demonstrates the efficiency of high levels of PEEP to reduce QS/QT in ARF but also shows its limitations: namely reduction in cardiac performance and in efficiency if the damage to one lung is significantly more pronounced than that to the other lung.

Acute Disease↗
PubMed1981

Dobutamine: a hemodynamic evaluation in human septic shock.

The hemodynamic effect of dobutamine infusion (DI) was studied in 19 patients with septic shock. DI resulted in hemodynamic improvement as indicated by a significant increase in cardiac index (+36%, p less than 0.001), stroke index (+15%, p less than 0.01), mean arterial pressure (+20%, p less than 0.01), and a significant decrease in aVDO2 (-27%, p less than 0.01). This hemodynamic improvement occurred concomitantly with a fall in both right and left filling pressures. Mean systemic arterial resistance remained unchanged with a scatter of individual responses depending on other factors, such as infusion rate, initial vascular resistance, and underlying hemodynamic setting. In patients mechanically ventilated, venous admixture in the lung (Qs/Qt) during DI increased significantly (+30%, p less than 0.001) and insignificantly reduced PaO2, but this adverse effect was not observed when PEEP was used in patients mechanically ventilated. It is concluded that dobutamine can be useful in management of septic shock, particularly when filling pressures are high because of fluid overload or cardiac failure.

Adult↗