Biomedical subjects

P Weidmann

Publications and source records attributed to P Weidmann.

At least 307 records · Page 17Linked to original sources

PubMed1975

[Proceedings: Correlations between blood pressure, body sodium/blood volume state and plasma renin in patients with terminal kidney insufficiency].

Plasma renin activity was found to correlate inversely with exchangeable sodium or blood volume in both normotensive and hypertensive hemodialysis patients. However, in the hypertensive patients mean circulating renin for any given sodium/volume state was markedly higher than in normotensive patients or normal subjects. Blood pressure correlated more closely with the products of circulating renin and exchangeable sodium (r = 0.55; p less than 0.001) or blood volume (r = 0.43; p less than 0.001) than with the individual components (r less than or equal to 0.39); multiple regression analysis including duration of previous hypertension as a second independent variable further improved these correlations (r = 0.66 and r = 0.63 respectively). This suggests that the sodium/volume state, circulating renin and vascular changes resulting from previous hypertension may be important complementary determinants of blood pressure in hemodialysis patients.

Blood Pressure↗

PubMed1975

[Single-needle hemodialysis].

In 10 patients on chronic dialysis a new hemodialysis technique, in which the extracorporeal and patient circulations are connected by controlled bloodflow reversal using a single cannula, has been compared with the conventional two-needle method. For two control periods (two-needle dialysis) and an intermediate test period (one-needle dialysis) involving 12 hemodialyses in each case, clinical, biochemical and hematolgic values and extracorporeal hemodynamic findings were studied. During the one-needle dialysis period the incidence of dialyzer membrane ruptures or muscular cramps, body weight, blood pressure, neurologic status, serum electrolytes and uric acid, and hemolysis rates, remained unchanged. There was however a diminution of dialysis effectiveness due to a significant bloodflow reduction of 26 percent (p less than 0.001) and extracorporeal blood recirculation of 6-54 percent. Correspondingly, there was a slight rise in the pre- and post-dialysis values for serum creatinine and urea nitrogen (p less than 0.0125). The observed reduction in effectiveness with one-needle dialysis can presumably be compensated by the use of systems with low recirculation and a correspondingly longer dialysis time. If these conditions are fulfilled, one-needle dialysis is a technically acceptable procedure which is comparatively easy to carry out and involves markedly less discomfort for the patient than the conventional two-needle method.

Blood Pressure↗

PubMed1975

Effect on aging on plasma renin and aldosterone in normal man.

The influence of aging on the renin-angiotensin-aldosterone system was evaluated by comparing young (20 to 30 yr) with elderly (62 to 70 yr) healthy subjects. Despite comparable body sodium-fluid balance in the two age groups, serum renin concentration, plasma renin activity and aldosterone concentrations were lower in the elderly. The age-related decreases in circulating renin and aldosterone concentrations were slight while subjects were supine and receiving normal sodium intake; when upright and during sodium depletion, they were more pronounced. Inverse renin-blood pressure interrelations were noted during two of four study conditions involving normal sodium intake or mild sodium depletion (r = --0.44 and --0.47, respectively), but not during progressive sodium depletion. Plasma renin levels were decreased in the elderly regardless of the presence or absence of an inverse relationship with blood pressure. Aldosterone and cortisol responses to corticotropin infusion were unaltered in the elderly. It is concluded that aging may cause a decrease in circulating renin, with parallel lowering of plasma aldosterone concentrations.

Adrenocorticotropic Hormone↗

PubMed1975

Control of aldosterone responsiveness in terminal renal failure.

Control of aldosterone responsiveness in terminal renal failure. Plasma aldosterone concentration in 30 hemodialysis patients correlated closely with renin concentration, renin activity or renin and potassium concentrations combined (r is greater than or equal to 0.62; P is less than 0.01), and increased consistently in response to upright posture or corticotropin administration. Aldosterone response to hemodialysis was variable. Significant correlations (r is greater than or equal to 0.65; P is less than 0.01) were demonstrated between postural plasma aldosterone and renin responses, between aldosterone responses to corticotropin and basal plasma aldosterone or renin and potassium values, between hemodialysis-induced changes in plasma aldosterone and those in potassium or renin; but not between various indexes of heparin treatment and aldosterone activity. Bilateral nephrectomy reduced basal plasma renin and aldosterone concentrations and aldosterone responsiveness in five preoperatively normoreninemic or hyperreninemic patients, but not in a hyporeninemic patient. These results demonstrate the complementary roles of circulating renin and potassium in the control of aldosterone release under basal and stimulatory conditions in patients with terminal renal failure. Administration of heparin in dosages used during long-term hemodialysis does not appear to significantly interfere with aldosterone control.

Adrenocorticotropic Hormone↗

PubMed1975

Role of the renin-angiotensin-aldosterone system in the regulation of plasma potassium in chronic renal disease.

The relationship between plasma potassium concentration and the renin-angiotensin-aldosterone system was evaluated in ten patients with chronic renal failure (creatinine clearance 10-56 ml/min). Under basal conditions and following various stimulation maneuvers, normokalemic patients demonstrated normal plasma renin and aldosterone levels. Five of six patients with hyperkalemia had diminished function of the renin-angiotensin-aldosterone system; their ability to conserve sodium during salt depletion was less than that of normokalemic patients. The data suggest that the maintenance of plasma potassium levels in these patients is dependent of the presence of a normally functioning renin-angiotensin-aldosterone system; aldosterone activity may be an important determinant of sodium conservation in patients with renal failure.

Adrenocorticotropic Hormone↗

PubMed1975