Biomedical subjects

L Billiet

Publications and source records attributed to L Billiet.

At least 37 records · Page 2Linked to original sources

PubMed1976

Mechanism of hypotensive effect during betaadrenergic blockade in hypertensive patients.

The mechanism of the hypotensive effect during beta-adrenergic blockade in hypertension was studied in 38 patients with renal or essential hypertension using the new cardioselective beta blocker, Tenormin. During 5 weeks hospitalization the patients received first a placebo for 5 to 12 days, then a 75 mg. dose of Tenormin was given daily for 1 week, and thereafter the dose was doubled weekly as necessary up to 600 mg. daily. The blood pressure decreased from 180 +/- 26.2/118. "/- 13.6 mm. Hg on placebo to 151 +/-25.5/96 +/-13.8 mm. Hg during the final hospitalization period on Tenormin (600 mg. daily). Six patients developed fluid retention and as this occurred blood pressure control was lost. A subsequent follow-up on an outpatient basis of 15 of the patients showed that when the active drug was replaced by a placebo blood pressure rose again, confirming that the initial fall in blood pressure was a genuine effect. Multistage bicycle ergometer exercise tests were performed at weekly intervals to test the degree of beta blockade and indicated that this was nearly complete when a dose of 600 mg. per day was used. A significant correlation between the hypotensive effect and the degree of beta blockade, assessed by exercise tachycardia, was observed. A slight but statistically significant decrease (26 per cent) was observed in the plasma renin concentration, measured recumbent in the morning. This decrease was, however, not correlated with the hypotensive effect of the drug. Although the cardiac output decreased significantly (from 5.5 +/-1.7 to 4.3 +/- 1.1 L per minute, p less than 0.001), no correlation was found in individual patients between the cardiac output and the blood pressure decrease. On the other hand, for the total group of catheterized patients (n = 28) the calculated total peripheral resistance did not change significantly. Yet a significant correlation was found between the changes in total resistance and the hypotensive effect. This suggests that the reaction of the peripheral vessels rather than the cardiac output decrease determines whether the drug will produce a major decrease of blood pressure in patients with hypertension.

Adult↗

PubMed1976

A new method to determine frequency characteristics of the respiratory system.

A technique is described allowing one to determine simultaneously the resistance and reactance of the total respiratory system for various frequencies. During spontaneous breathing, regularly recurring impulses are produced at the mouth by means of a loud speaker. A Fourier analysis of the mouth pressure and flow signals yields mean resistance and reactance values, over 16 s, for all harmonics of 2 Hz up to 30 Hz. The values are in good agreement with those obtained in the absence of breathing and those determined by means of the forced oscillation technique and by body plethysmography. The reproducibility of the measurements is satisfactory (coefficient of variation: 11.6%).

Electronics↗

PubMed1976

Xenon and nitrogen single-breath washout curves in patients with airway obstruction.

In patients with chronic obstructive lung disease, we determined single-breath N2 and 133 Xe washout curves, and regional distributions of volumes (Vr) and of 133Xe boluses inhaled at residual volume (VIRV). Patients suffering from emphysema with minimal airway obstruction demonstrated large closing volumes and apicobasal distribution gradients, apparently because of a steep pulmonary recoil pressure-volume curve. In one subject with basal small airway disease there was no vertical gradient in regional residual volume; closing volume was increased with the 133Xe technique but almost absent with the N2 technique. Patients with moderate-to-severe airway obstruction had upward-sloping alveolar plateaus without distinct phase IV, and small apicobasal differences in Vr and VIRV. The latter resulted probably from increased regional differences in time constants counteracting the influence of gravity. Finally, patients with severe airway obstruction and basal emphysema demonstrated a rising N2 but a descending 133Xe plateau; the gradient for VIRV was normal, and reversed for Vr. This pattern was attributed to nongravitational differences in time constants causing a first in-first out distribution.

Adolescent↗

PubMed1976

Haemodynamic effects of Sar1-Ala8-angiotensin II in patients with renovascular hypertension.

Sar1-Ala8-angiotensin II was infused intravenously (10 mug/kg/min) in 14 patients with renovascular hypertension, including 11 with renal artery stenosis. Brachial artery pressure and heart rate remained unchanged in six patients who were on a daily sodium intake of 130 mEq. In 12 tests performed after sodium depletion, the decrease in mean arterial pressure ranged from 13 to 76 mm Hg and showed a significant correlation with the plasma renin concentration prevailing immediately before the infusion of the drug (r = 0.81; p less than 0.001). The hypotensive response was due to a drop in total peripheral resistance. Heart rate and cardiac output showed slight increases 10 min after the start of saralasin infusion.

Adult↗

PubMed1975

Predictive value of various parameters for the antihypertensive effect of the beta blocker ICI 66,082 (1).

The antihypertensive effect of the new beta-blocker, ICI 66,082 was studied in 37 patients with renal or essential hypertension. A daily dose of 75 mg produced a significant antihypertensive effect and a further blood pressure decrease was obtained by increasing the daily dose up to 300 mg; at this treatment level, the antihypertensive effect averaged 29.4/24.0 mm Hg. Increasing the dose from 300 to 600 mg daily did not produce a significant additional blood pressure decrease. Six of the 37 patients retained fluid, producing a loss in the antihypertensive effect. No significant correlation was found between the percentage systolic blood pressure fall and the following parameters determined before therapy: systolic blood pressure and its variability, heart rate (at rest and after stimulation by exercise or isoproterenol), cardiac output and total peripheral resistance, renin concentration (at rest and after stimulation) and urinary excretion of catecholamines and derivates.

Adrenergic beta-Antagonists↗

PubMed1974