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Biomedical subjects

D Payen

Publications and source records attributed to D Payen.

123 records · Page 7Linked to original sources
PubMed1985

[Plasma renin activity and prostaglandin E2 in hypotension induced by sodium nitroprusside].

Sodium nitroprusside (SNP) is a potent, effective and readily reversible vasodilating agent frequently used in anaesthesia for deliberate hypotension. Moderate hypotension induced by SNP activated catecholamine and vasopressin secretions, and the renin-angiotensin system, resulting in partial antagonism of the hypotensive response to SNP. Furthermore, this increase in renin release was involved in the hypertensive rebound after SNP withdrawal. This activation of vasoconstrictor systems led to pharmacological associations aimed at reducing the risk of cyanide poisoning. The physiological interrelationship between prostaglandins and renin secretion has now been well established but, as far as we know, no paper existed concerning prostaglandins during SNP-induced hypotension. In such hypotension (Pa: -30%), monitored by invasive and non invasive haemodynamic techniques (pulsed Doppler), the variations in plasma renin activity (PRA) and in venous and arterial plasma PGE2 concentrations (V PGE2 and A PGE2), determined by radioimmunoassay, were studied in anaesthetized dogs. Invasive haemodynamic data were similar to previous reports. Common carotid diameter increased (p less than 0.05), with a constant common carotid blood flow. PRA (p less than 0.05), V PGE2 (p less than 0.05) and A PGE2 (p less than 0.05) increased. PRA and V PGE2 were highly correlated before and after SNP. SNP resulted in hypotension with reflex sympathetic activation and dilatation of large arteries. Carotid blood flow autoregulation was maintained. Whilst pulmonary removal of PGE2 remained unchanged, an increase in A PGE2 may have been involved in the vasodilator mechanisms.

Animals↗
PubMed1985

Diagnostic yield of bronchoalveolar lavage in pneumonitis occurring after allogeneic bone marrow transplantation.

Fifty-two bronchoalveolar lavages (BAL) were performed in order to investigate 46 episodes of pneumonitis that occurred after allogeneic bone-marrow transplantation. No complications have been attributed to this procedure. A specific etiologic diagnosis was obtained in 24 of 46 episodes (52%) by 26 of 52 BAL (50%). Cytomegalovirus (CMV), diagnosed by the presence of typical inclusions, was the pathogen most frequently identified by BAL (13 of 46 episodes) and was associated with other causes of pneumonia in 4 patients. The other causes of pneumonitis diagnosed by BAL were: giant-cell pneumonia: 1, aspergillosis alone: 3, Pneumocystis carinii: 1, Hemophilus influenzae: 3, isolated pulmonary hemorrhage: 3. One false negative (aspergillosis, n = 1) was diagnosed at autopsy. The overall mortality rate of these episodes was 24%. Thus, BAL appears to be a rapid and reproducible diagnostic method for monitoring pneumonitis in grafted patients, particularly CMV pneumonitis, and may avoid the need for surgical biopsy.

Adolescent↗
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

Right atrial septal aneurysm: an unusual cause of recurrent pulmonary embolism.

Angiography was used to diagnose atrial septal aneurysm in a 46-yr-old man suffering from recurrent pulmonary emboli, who had normal venograms of his lower extremities. This case demonstrates the usefulness of searching for sources of emboli other than deep venous thrombosis, but illustrates the limits of two-dimensional echocardiography in diagnosing atrial septal aneurysm.

Heart↗
PubMed1983

Hemodynamic effects of head-down tilt in normal subjects and sustained hypertensive patients.

Central and forearm arterial and venous hemodynamics, arterial baroreflex sensitivity, plasma renin activity, and catecholamines were studied in supine position and after -10 degrees head-down tilt in 29 patients with sustained essential hypertension and in 29 normotensive controls of the same age and sex. In both populations, blood pressure, heart rate, and arterial baroreflex sensitivity did not change during the maneuver. Head-down tilt induced a similar increase in cardiopulmonary blood volume in controls and hypertensives, whereas the increase in central venous pressure, cardiac output, and forearm blood flow was higher in hypertensives. Forearm venous tone decreased in controls (from 16.6 +/- 0.8 to 13.8 +/- 0.9 mmHg X ml-1 X 100 g-1; P less than 0.01) but did not change in hypertensive patients (24.9 +/- 1.6 vs. 25.1 +/- 1.9. The magnitude of forearm vascular resistance changes induced by head-down tilt were significantly related to the basal venous tone in the overall population (P less than 0.01). The decrease in plasma renin activity and plasma catecholamines was similar in the two groups. The study provides the evidence that the higher increase in cardiac output and local flow observed in head-down tilt in hypertensive patients is probably due to a higher change in central venous pressure related to a decrease in venous distensibility.

Adult↗