Effect Of Low-Dose Dopamine Infusion Research Articles

Effect of intravenous dopamine infusion on pituitary and thyroid function and on nephroprotection

INTRODUCTION; Catecholamines, including dopamine, are used in cardiac intensive care. The aim of the study was to assess the effect of intravenous dopamine infusion on the function of pituitary gland in patients with acute cardiac failure. We analyzed changes in the serum levels of thyroid-stimulating hormone (TSH) and adrenocorticotropic hormone (ACTH), as well as potential nephroprotection. The study involved 29 patients with chronic decompensated heart failure (New York Heart Association class III/IV; mean age 77.4 ± 13.3 years). Dopamine was administered intravenously in doses varying from 1 to 5 μg/kg/min. Measurements of TSH, free triiodothyronine (FT3), free thyroxine (FT4), and ACTH were taken directly before dopamine infusion, after 12 hours of continuous infusion, and 12 hours after the 72-hour infusion was completed. Serum FT3 levels were significantly higher before dopamine infusion than at 12 hours post infusion (5.12 ± 1.16 vs. 4.27 ± 0.89 pmol/l, P < 0.005). Serum FT4 levels before the infusion were significantly higher than after 12 hours of continuous infusion as well as after 12 hours post infusion (18.79 ± 5.33 vs. 17.06 ± 4.61 pmol/l, P < 0.05; 18.79 ± 5.33 vs. 16.26 ± 4.53 pmol/l, P < 0.05, respectively). There were no statistically significant differences between serum TSH and ACTH levels or in creatinine clearance before, during, and 12 hours post infusion. Intravenous infusion of dopamine may downregulate endocrine thyroid function; however, it has no significant effect on the pituitary gland-derived TSH and ACTH. There was no significant nephroprotective effect of low-dose dopamine infusion in patients with chronic decompensated chronic heart failure.

The Renal Effects of Low-Dose Dopamine Infusion in Elderly Patients Hospitalized for Acute Decompensated Heart Failure

Background: Prior studies have shown that women admitted with acutely decompensated heart failure have higher left ventricular ejection fractions (LVEF) than their male counterparts. In this study, we sought to determine if other echocardiographic differences exist between men and women hospitalized with ADHF and if gender is predictive of hospital length of stay (LOS), readmission and mortality. Methods: We retrospectively studied 182 consecutive patients admitted with ADHF to a tertiary teaching hospital. Echocardiographic variables were recorded (blinded to gender) in addition to clinical characteristics and 6-month outcomes. Results: Compared to men, women had higher mean LVEF, smaller LVs and left atria (LA), thinner LV posterior wall thickness, higher transmitral E and A velocities, and less right ventricular (RV) systolic dysfunction. In contrast, the degree of mitral (MR) and tricuspid regurgitation (TR) and RV systolic pressure (RVSP) were similar in both sexes, as were hospital LOS, and readmission and death at six months. Continuous and categorical variables were analyzed using student’s t-test and chisquared test respectively. Conclusions: LOS and 6 month outcomes are similar in women and men despite the presence of a higher LVEF and less RV systolic dysfunction in women, suggesting that other parameters, probably affecting diastolic function, play a greater role in women and should be targeted in an attempt to improve clinical outcomes.

Bad Medicine: Low-Dose Dopamine in the ICU

Low-dose dopamine administration (ie, doses < 5 microg/kg/min) has been advocated for 30 years as therapy in oliguric patients on the basis of its action on dopaminergic renal receptors. Recently, a large, multicenter, randomized, controlled trial has demonstrated that low-dose dopamine administered to critically ill patients who are at risk of renal failure does not confer clinically significant protection from renal dysfunction. In this review, we present the best evidence and summarize the effects of low-dose dopamine infusion in critically ill patients. We review the history and physiology of low-dose dopamine administration and discuss the reasons why dopamine is not clinically effective in the critically ill. In addition to the lack of renal efficacy, we present evidence that low-dose dopamine administration worsens splanchnic oxygenation, impairs GI function, impairs the endocrine and immunologic systems, and blunts ventilatory drive. We conclude that there is no justification for the use of low-dose dopamine administration in the critically ill.

Effect of low-dose dopamine on serum concentrations of prolactin in critically ill patients

Dopamine is a naturally occurring catecholamine with actions in the central nervous system and endocrine systems, including inhibition of prolactin release from the pituitary gland. Prolactin secretion has been shown to be increased in response to physiological stress, while hypoprolactinaemia is associated with a reduction in the cellular immune response. We have investigated the effects of low-dose infusion of dopamine 2.5 micrograms kg-1 min-1 on serum concentrations of prolactin in critically ill patients. Six hours after commencing the dopamine infusion, mean serum prolactin concentration had decreased from 746.95 to 128.9 mu. litre-1 (normal range 84-488 mu. litre-1). This represented a mean reduction of 79.2%, with 35% of patients exhibiting a subnormal concentration while receiving dopamine. This reduction was reversed after cessation of dopamine and reproducible on re-institution. This suppression of the release of dopamine may be a detrimental side effect of low-dose dopamine infusion in critically ill patients.

Interleukin-2—Induced renal dysfunction in cancer patients is reversed by low-dose dopamine infusion

Recombinant interleukin-2 (rIL-2) is widely used in patients with advanced cancer to enhance killer cell functions. However, the main drawback of rIL-2 therapy is the frequent development of oliguric acute renal failure (ARF), presumably due to a vascular leak syndrome. The aim of this study was to evaluate the effect of low-dose dopamine infusion on this form of ARF. Nine patients with metastatic renal cancer and previous unilateral nephrectomy were treated with a continuous intravenous infusion of rIL-2 (3 × 10 6 Cetus units/m 2/d) for 5 days (study A). After 1 week, all the patients repeated the same cycle, but with the addition of a continuous intravenous infusion of dopamine (2 μg/min/kg body weight) that was started at the third day of treatment (study B). During study A, all patients showed a progressive (up to 34%) decrease of creatinine clearance. After rIL-2 withdrawal, these alterations persisted and were associated with a reduction in urinary output, sodium urinary excretion, and plasma protein. In study B, dopamine administration after renal function impairment (‡glomerular filtration rate = −44%) led to a prompt improvement of creatinine clearance. Creatinine clearance showed a further significant enhancement after the withdrawal of both drugs, reaching a value within the baseline range on the third day of follow-up. Similarly, the decline in urinary output and sodium excretion during rIL-2 was promptly counteracted by dopamine; in addition, after withdrawal of rIL-2 and dopamine, plasma protein levels were normalized. In conclusion, our data suggest that rIL-2-induced ARF in cancer patients is due to renal hypoperfusion mainly caused by a reduction in oncotic pressure. Importantly, intravenous infusion of dopamine at low dosage is effective in reversing this form of renal impairment; such a therapeutic approach, while reducing recovery time, avoids dose reduction or discontinuation of rIL-2 treatment.

Effects of Low-Dose Dopamine Infusion on Cardiovascular and Renal Functions, Cerebral Blood Flow, and Plasma Catecholamine Levels in Sick Preterm Neonates

Effects of 2 and 4 micrograms/kg/min dopamine infusion on cardiovascular and renal functions, cerebral blood flow (CBF) and plasma catecholamine levels were studied in sick preterm neonates during the first four days of life. Preterm infants were found to have an enhanced responsiveness to the pressor effects of dopamine during this period. Comparison of the renal effects of 2 and 4 micrograms/kg/min dopamine in 61 preterm infants indicate that 2 micrograms/kg/min dopamine induces maximum diuresis and natriuresis during the first day of life provided that systemic blood pressure is within the predicted normal range. Although administration of 4 micrograms/kg/min dopamine induces further increases in blood pressure and glomerular filtration rate, urine output and sodium excretion remain similar to that on 2 micrograms/kg/min of the drug. These findings demonstrate that the direct tubular effects of dopamine play an important role in the diuretic and natriuretic action of the drug in the one-day old preterm infant. In five preterm neonates, changes in CBF transiently paralleled the dopamine-induced alterations in systemic blood pressure indicating that autoregulation of CBF is impaired but not completely ineffective in the one-day old preterm infant. In eight term neonates, increases in blood pressure had no effect on CBF. Measurements of plasma dopamine and norepinephrine levels in 14 preterm neonates and five children suggest that decreased metabolism of dopamine may contribute to the enhanced pressor responsiveness to dopamine in sick preterm infants.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Low-Dose Dopamine Infusion on Cardiopulmonary and Renal Status in Premature Newborns With Respiratory DistLow-Dosedrome

To study the effects of infusion of low doses of dopamine hydrochloride on cardiopulmonary and renal status in premature newborns with respiratory distress syndrome, 49 newborns were randomly assigned to three groups: group 1 (18 patients) received no dopamine and was the control group; group 2 (16 patients) was infused with a dose of dopamine measuring 1.0 micrograms/kg of body weight per minute for 72 hours; and group 3 (15 patients) was infused with a dose of dopamine measuring 2.5 micrograms/kg of body weight per minute for 72 hours. Birth weights, gestational ages, post-natal ages, and cardiopulmonary status of all groups at the start of the study were comparable. Continuous infusion of these low doses of dopamine for 3 days after birth did not significantly improve levels of blood gases, acid-base balance, or clinical outcome. In newborns with systemic hypotension, dopamine improved cardiovascular status and caused early return of blood pressure to the normal range. Infusion of low doses of dopamine produced mild to moderate natriuresis and insignificant increases in glomerular filtration rate and urine volume.

Metabolic Effects of Low-Dose Dopamine Infusion in Normal Volunteers

1. Dopamine in 5% (w/v) D-glucose was infused into five healthy male volunteers at doses of 2, 5 and 10 micrograms min-1 kg-1 over three sequential periods of 45 min each. 2. Oxygen consumption, respiratory exchange ratio, blood glucose concentration and plasma levels of free fatty acids, glycerol, lactate, dopamine, adrenaline and noradrenaline were measured. The results were compared with values obtained during infusion over the same time period of the corresponding volumes of 5% (w/v) D-glucose alone. 3. Energy expenditure calculated from the oxygen consumption and the respiratory exchange ratio was higher than control values during infusion of dopamine (P less than 0.001, analysis of variance) specifically at a rate of 10 micrograms min-1 kg-1 (P less than 0.05) when it was 14% higher, but not at a rate 2 of or 5 micrograms min-1 kg-1. The plasma noradrenaline concentration was 74 and 230% and the blood glucose concentration was 21 and 36% higher than control values at 5 and 10 micrograms of dopamine min-1 kg-1, respectively (P less than 0.01). At 10 micrograms of dopamine min-1 kg-1 the plasma free fatty acid concentration was 70% and the plasma glycerol concentration was 80% higher than during the control infusion (P less than 0.01). The respiratory exchange ratio and the plasma lactate concentration were the same in the two groups and did not alter during the dopamine infusion. The plasma adrenaline concentration rose significantly (P less than 0.01), but only transiently, during dopamine infusion at a rate of 2 micrograms min-1 kg-1. 4. Dopamine at low doses has metabolic effects. It increases the blood glucose concentration and the circulating noradrenaline level at an infusion rate of 5 micrograms min-1 kg-1. It increases energy expenditure and circulating free fatty acid and glycerol levels at an infusion rate of 10 micrograms min-1 kg-1, presumably due to stimulation of lipolysis.

Catecholamines and pituitary-function. V. Effect of low-dose dopamine infusion on basal and gonadotropin-releasing hormone stimulated gonadotropin release in normal cycling women and patients with hyperprolactinemic amenorrhea.

To verify the role of dopaminergic mechanisms in the control of gonadotropin secretion in normal and hyperprolactinemic women, we examined the gonadotropin response to GnRH (100 micrograms i.v.) administration in both basal conditions and during low-dose dopamine (DA, 0.1 microgram/kg/min) infusion. Hyperprolactinemic women, either with microadenoma or without radiological signs of pituitary tumor, showed significantly enhanced LH and FSH responses to GnRH in comparison with normal cycling women. 0.1 microgram/kg/min DA infusion did not result in any appreciable suppression of serum gonadotropin levels but significantly reduced the LH and FSH responses to GnRH in both normal and amenorrheic hyperprolactinemic women. Although both LH and FSH levels remained higher in hyperprolactinemic patients than in normal women after GnRH, the gonadotroph's sensitivity to DA inhibition was normal in the hyperprolactinemic group, as both control subjects and patients with hyperprolactinemic showed similar per cent suppression of GnRH-stimulated gonadotropin release during DA. These data confirm that hypothalamic DA modulates the gonadotroph's responsiveness to GnRH. The increased LH and FSH responses to GnRH in hyperprolactinemic patients and their reduction during low-dose DA infusion seem to indicate that endogenous DA inhibition of pituitary gonadotropin release is reduced rather than enhanced in women with pathological hyperprolactinemia.

Catecholamines and pituitary function. IV. Effects of low-dose dopamine infusion and long-term bromocriptine treatment on the abnormal thyrotroph (TSH) dynamics in patients with pathological hyperprolactinaemia.

In order to gain further insight into the role of dopamine (DA) in the control of TSH release and to investigate whether an increased or defective DA inhibition on pituitary thyrotrophs may be considered responsible for the abnormal TSH dynamics in pathological hyperprolactinaemia, we examined the effect of low-dose DA infusion on TRH stimulated TSH secretion in normally cycling women and in patients with pathological hyperprolactinaemia. The effect of long-term bromocriptine therapy on TSH dynamics was also evaluated in a selected group of hyperprolactinaemic women. Fifty-two hyperprolactinaemic patients with no other signs of pituitary or thyroid dysfunction had significantly higher mean TSH serum concentrations and mean TSH peak values after TRH administration than 75 healthy controls. Furthermore, the TSH rises induced by the DA-synthesis inhibitor alpha-methyl-p-tyrosine (AMPT, 500 mg orally) were enhanced in both prolactinoma and 'idiopathic hyperprolactinaemia' patients as compared with controls. There was a positive correlation between the TRH- and AMPT-induced TSH rises in the hyperprolactinaemic group. Low-dose DA infusion (0.1 microgram/kg X min) reduced TSH response to TRH in both regularly cycling women and patients with hyperprolactinaemic amenorrhoea. Longterm bromocriptine therapy (2.5 mg tid over 60-150 days) not only normalized serum Prl levels, but also reduced the TSH response to TRH in 7 hyperprolactinaemic women who had presented exaggerated TSH responses to the basal TRH test.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Low-Dose Dopamine Infusion on Insulin and Glucagon Release in Fasting Normal Man

The effect of a low-dose infusion of dopamine on basal circulating concentrations of insulin, glucagon and glucose in six healthy male subjects is reported. Dopamine (0.1 microgram/kg/min) or placebo was given intravenously for 60 minutes. During infusion of the catecholamine, circulating plasma dopamine was 3.46 +/- 1 ng/ml. No change in circulating concentrations of insulin, glucagon and glucose were seen during infusion of dopamine when compared with placebo infusion. It is concluded that dopamine acting at a D2 receptor is unlikely to be of physiological importance in regulation of basal pancreatic islet cell function in man.

Effect of low-dose dopamine infusion on prolactin and thyrotropin secretion in preterm infants with hyaline membrane disease.

The effect of low-dose (2-4 micrograms/kg/min) and long-term (greater than or equal to 46 h) dopamine infusion on serum prolactin and thyrotropin concentrations was investigated in 8 preterm infants with hyaline membrane disease. Dopamine was administered for systemic hypotension and/or for impending renal failure. Serum prolactin decreased from 1,314.5 +/- 422.7 microU/ml to 489.9 +/- 464.1 microU/ml (p less than 0.005), while serum thyrotropin fell from 3.77 +/- 2.27 microU/ml to 1.01 +/- 0.25 microU/ml (p less than 0.025) during dopamine infusion. Our data indicate that exogenous dopamine exerts an inhibitory effect on the secretion of prolactin and thyrotropin even in the sick preterm neonate. The role of prolactin in fetal lung maturation and in regulation of the neonatal tissue water stores is discussed. The results of the present study are also useful in explaining the renal effects of long-term low-dose dopamine infusion in the sick preterm infant.