D. El Allaf

The use of low doses of dopamine in intensive care medicine

The dopamine alpha- and beta-adrenoceptor dose-response curves are investigated in four patients who are exempt from cardiovascular disease. A dose-related increase in CO, HR and SV is observed with infusion rates of up to 3 micrograms kg-1 min-1. With concentrations greater than 10 micrograms kg-1 min-1, both BP and SVR increase. Low-dose dopamine infusion less than 3 micrograms kg-1 min-1 is investigated in ten other patients. With this infusion rate, a selective renal vasodilation is induced without peripheral or cardiac beta-adrenoceptor activation. Dopamine is responsible for an increase in diuresis FENa, GFR and RBF. These properties are indicated in renal failure, and when haemodynamic support is required in cardiac failure, if an infusion rate of up to 10 micrograms kg-1 min-1 is able to reverse cardiac insufficiency.

Combined haemodynamic effects of low doses of dopamine and dobutamine in patients with acute infarction and cardiac failure

The haemodynamic effects of an optimal dose of dobutamine (DUo) (6.7 +/- 4.2 micrograms kg-1 min-1) and the combination of this optimal dose minus 2.5 micrograms kg-1 min-1 of dobutamine (DU) plus dopamine 2.5 micrograms kg-1 min-1 (DA) were studied in a first group of 12 consecutive patients with acute myocardial infarction (AMI) and cardiac failure (CF). DUo decreased pulmonary wedge pressure from 23.5 to 16 mm Hg (P less than 0.01), systemic vascular resistance from 1 774 to 1 417 dynes s cm-5 (P less than 0.01). DUo increased cardiac output from 3.21 to 4.55 litres/min (P less than 0.01) and urinary flow (UF) from 20 to 68 ml/h (P less than 0.01). Heart rate and blood pressure did not change significantly. DUo - DU + DA significantly increased UF from 68 to 107 ml/h (P less than 0.05) while the other parameters remained unchanged with respect to DUo. The positive effect of DA on UF was confirmed in a second group of 12 consecutive patients by comparing the successive effects of DA + DUo and DUo + DU : all previously described parameters remained unchanged except UF which decreased from 107 to 65 (P less than 0.01). We conclude that in patients with CF and AMI, association of DA and DUo is useful in obtaining both inotropic and diuretic effects.

The new inotropic phosphodiesterase inhibitors

Compounds with phosphodiesterase inhibitory activity stimulate myocardial contractility by increasing the intracellular cyclic AMP concentrations. They can also increase Ca2+ entry and inhibit Ca2+ sequestration by the sarcoplasmic reticulum. Xanthines produce bronchodilation with associated venous and arteriolar dilation. However, their use is limited by their positive chronotropic effect and other side effects at high plasma levels. New phosphodiesterase inhibitors have been perfected: they are more specific with little chronotropic effect. Increasing the sensitivity of the myofilaments to Ca2+, and other unclear mechanisms may be involved in the inotropic action of these drugs. These new promising active compounds are described and discussed. They augment cardiac performance and improve regional distribution of blood flow and symptoms. However, their influence on the long-term outcome of severe heart failure has yet to be determined.

Effect of Age and Sex on the N-Demethylation Rate of 14C-Aminopyrine, Studied by the Breath Test

The effect of age and sex on the N-demethylation rate of 14C-aminopyrine was studied by breath test in 28 normal subjects (12 men, 16 women) aged 26 to 86. It was found that demethylation of aminopyrine was inversely related with age and unaffected by sex. 6 out of 8 patients aged 70 or over, had breath test values within the range of values obtained in 31 patients with alcoholic cirrhosis. In the elderly, a breath test can therefore be considered abnormal only if it is compared with a control group of the same age.

Old and new inotropic drugs

An ideal cardiotonic agent should improve cardiac contractility and increase the oxygen supply to various tissues without inducing tachycardia, arrhythmias, decrease in coronary blood flow or increment in oxygen requirements of the myocardium. It should also be safe and orally active and have a persistent action. The aim of this paper is to describe various positive inotropic drugs at our disposal. The hemodynamic effects and the indications of adrenaline, noradrenaline, isoprenaline, dopamine, dobutamine and cardiac glycosides are presented first. Then several new promising orally active compounds are discussed.

Role de l' alpha 1-glycoproteine acide plasmatique dans la fixation de l'aminopyrine.

AbstractUnder certain pathological conditions the binding of various substances by serum proteins is altered. The plasma concentrations of alpha, -acid glycoprotein, also known as orosomucoid are reported to be elevated in stressful situation and in certain disease states like acute myocardial infarction. The binding of aminopyrine to serum proteins and α1-acid glycoprotein was determined using equilibrium dialysis.It appears that α1-acid glycoprotein has specific binding sites for aminopyrine. Aminopyrine was also bound to other serum proteins. On addition the results indicate that an increase of α1-acid glycoprotein to concentrations such as those seen in some pathological states does not really alter the percent of aminopyrine bind to serum proteins.

Potentiation of the action of oral anticoagulants by amiodarone.

SummaryAmiodarone is widely used in the treatment of cardiac arrhythmias and coronary insufficiency. A potentiation of the hypoprothrombinemic response by this drug has already been reported.A new observation confirms the danger of such an interaction, and the necessity of careful surveillance when amiodarone is prescribed simultaneouslv with coumarins.