[Ventilation with expiratory positive pressure protects against the harmful effects of cardiac output increase].
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Biomedical subjects
Publications and source records attributed to G Simonneau.
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The hemodynamic and respiratory effects of spontaneous ventilation with continuous positive airway pressure (CPAP) and mechanical ventilation with positive and expiratory pressure (CPPV) were compared in six patients with acute respiratory failure. Arterial and mixed venous gases, cardiac output, oxygen delivery and consumption, airway and oesophageal pressures were measured, with each patient on intermittent positive pressure ventilation (IPPV), CPAP and CPPV with the same level of positive and expiratory pressure (PEEP = 20 cmH2O). CPAP was as efficient as CPPV for improving arterial oxygenation. Cardiac output was higher on CPAP than on CPPV due to a lower intra-thoracic pressure with spontaneous ventilation, thus oxygene transport was higher with this methode. However total oxygene consumption and PaCO2 were slightly increased with CPAP due to a higher breathing's work. So, CPAP is as efficient as CPPV at the same level of PEEP in improving intra-pulmonary shunt and PaO2, without adversely affecting cardiac output.
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To determine the influence of intermittent positive pressure breathing (IPPB), the level of pulmonary capillary wedge pressure (PCWP) was compared during IPPB and after a short period off the respirator in 68 occasions on 42 patients with an acute respiratory failure (ARF) of various etiologies. During IPPB, the average PCWP was in the normal range in patients with toxic or neurologic comas and in cases of increased pulmonary capillary permeability edema (IPCPE), PCWP slightly increased within chronic obstructive pulmonary disease (COPD) complicated with ARF and in hemodynamic acute pulmonary edema (HAPE). During the weaning stage, PCWP decreased in the groups of coma, COPD, and IPCPE, but increased in HAPE. The weaning test demonstrates that IPPB influenced PCWP in all patients. Therefore, PCWP cannot be assumed to represent the left ventricle filling pressure. The weaning test allows differentiation of IPCPE from HAPE. In the event of over-infusion or hypovolemia, PCWP measured under IPPB can lead to misinterpretation if not followed up by a second measurement off the respirator.
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To assess the value of CT in chronic pulmonary embolism (CPE), CT scans and pulmonary angiograms of 21 consecutive patients were reviewed. Computed tomography was better than angiography in assessing proximal clots (three thrombi not seen by angiography, three angiographic false-positives confirmed by surgery). Furthermore, CT was able to analyze pulmonary arteries distal to angiographic amputations. Computed tomography was less sensitive than angiography for vascular distortions (38 vs. 50%) and stenosis (35 vs. 71.8%). Pulmonary infarctions were better detected and characterized by CT than by angiography. Isolated parenchymal ground-glass opacities were seen by CT in 18 patients, especially in those with right cardiomegaly. High resolution CT delineated them better than did standard CT. Computed tomography may be a useful adjunct to angiography in the assessment of CPE.
OBJECTIVE: To compare oral anticoagulant treatment (fluindione) started on either the 1st or the 10th day of a low-molecular-weight heparin (enoxaparin) treatment for deep vein thrombosis confirmed by venography. DESIGN: An open, multicenter, randomized study in two parallel treatment groups. INTERVENTIONS: All patients received enoxaparin, 1 mg/kg s.c. twice daily, and oral fluindione, 20 mg once daily, either beginning on day 1 or on day 10 of the enoxaparin treatment. Enoxaparin was discontinued once the international normalized ratio under fluindione was stable between 2.0 and 3.0 over 2 days. Fluindione treatment was maintained during a 3-month follow-up period. OUTCOME MEASUREMENTS: Specific examinations (venography and/or V/Q lung scanning and/or angiography) were performed only in the event of a clinically suspected recurrence of venous thromboembolism during the 3-month follow-up period. All cases were blindly assessed by an independent Reading Committee. RESULTS: A clinically suspected venous thromboembolism was confirmed by objective tests in 1 of 223 patients (group of delayed introduction of fluindione; n = 111). Equivalence was demonstrated between the two treatment schedules (p < 0.0001) for a maximal difference of 10% (90% confidence interval: -2.42 to 0.58). The mean duration of hospitalization was significantly reduced (p = 0.0001) in the group with early introduction of fluindione. The incidence of hemorrhage was comparable between the two treatment groups. CONCLUSION: Early and delayed introduction of oral anticoagulant treatment in association with subcutaneous enoxaparin in patients with deep vein thrombosis was shown to be equivalent in preventing the recurrence of venous thromboembolism. In patients with early introduction of oral anticoagulant, hospitalization was significantly reduced.
We present a new method to measure thoraco-abdominal perimeter variations using differential linear transformers inserted in belts. The high sensitivity (250 mV/mm), the low time drift (1 mV/24 h compared to a 1 V output for a tidal volume), the good frequency response (up to 10 Hz) and low cost (12,000 FF) are the major advantages over other devices. After calibration (using change contribution of thorax and abdomen and the least square method for calculation of volume-motion coefficients), estimated tidal volumes in 23 adults in supine position are within 0.06 +/- 5.17% and changes in functional residual capacity (43-453 ml) are within 3.4 +/- 15.3% when compared with direct spirometry. These results show that the method can be used to monitor ventilation accurately in supine healthy subjects.
The authors report on three cases of rheumatoid aortic valve insufficiency. The three patients had classic sero-positive rheumatoid arthritis. In one patient aortic valve insufficiency and pericarditis occurred simultaneously; aortic valve insufficiency appeared in two patients less than two years and in the third patient 17 years after the beginning of arthritis. In the first two cases, the aortic regurgitation evaluated by echocardiography and angiography was not severe enough to require valvular replacement. In the third patient, rheumatoid granuloma of the aortic valve caused fatal aortic insufficiency.
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