Dopamine administration in oliguria and oliguric renal failure

The optimization of renal function in acute illness

The development of acute renal failure increases the morbidity, the mortality and the duration of hospital stay of all patients who are treated in intensive-care units. Consequently, the prevention of renal failure, and especially that of oliguric acute renal failure, has a high priority in the management of patients who are seriously-ill. The identification of risk factors, the pretreatment of patients who are in high-risk categories and the maintenance of adequate hydration, oxygenation, cardiac output and renal blood flow are the first-line priorities in management. The use of loop diuretic agents, mannitol and dopamine, separately or in combination, probably are effective prophylactic measures. They also may have therapeutic benefit in the maintenance of a non-oliguric state in the presence of acute renal failure, although there is less scientific support for this role. Such manoeuvres are worthy of trial before an oliguric state is accepted. They are more likely to be efficacious if they are instituted early.

Cardiovascular and renal hemodynamic effects of intravenous infusions of the selective DA1 agonist, fenoldopam, used alone or in combination with dopamine and dobutamine

Fenoldopam (0.1 and 0.2 microgram/kg/min i.v.) was administered to pentobarbital-anesthetized dogs alone and combined with dopamine (DA) and dobutamine. Renal blood flow, heart rate, and mean arterial pressure were measured. Both dosages of fenoldopam increased renal blood flow without altering blood pressure, similar to the effects of DA (1 and 2 micrograms/kg/min). Administration of fenoldopam with only DA (1 microgram/kg/min) produced further increase in renal blood flow. After administration of phenoxybenzamine (15 mg/kg i.v.), DA produced significant increments in renal blood flow and reductions in renal vascular resistance when compared with experiments without phenoxybenzamine, suggesting even low dosages of DA exert alpha-adrenoceptor agonist activity. Dobutamine (2 and 4 micrograms/kg/min) increased renal blood flow about 37% of that produced by DA. Fenoldopam added to dobutamine produced similar increments in renal blood flow as DA. Fenoldopam did not affect the increase in cardiac contractile force produced by DA and dobutamine. Thus, fenoldopam alone or in combination with DA had no advantage over 2 and 4 micrograms/kg/min DA to further increase renal blood flow. In contrast, fenoldopam with dobutamine produced greater increments in cardiac contractile force than DA and equivalent increases in renal blood flow as DA.

Effects of low-dose dopamine therapy in the oliguric patient with preeclampsia

Central hemodynamic and renal responses to low-dose dopamine (1 to 5 micrograms/kg/min) infusion were studied in six oliguric (less than 0.5 ml/kg/hr) patients with severe preeclampsia. Hemodynamic parameters were measured and renal function tests were done before and during therapy. There was a significant rise in urine output from a mean (+/- SD) of 21 +/- 10 to 43 +/- 23 ml/hr, accompanied by a rise in cardiac output from 6.8 +/- 1.8 to 8.0 +/- 2.3 L/min (p less than or equal to 0.05). There were no significant changes in blood pressure, central venous pressure, or pulmonary capillary wedge pressure. The fractional excretion of sodium, negative free water clearance, and osmolar clearance tended to rise during dopamine therapy. No adverse maternal or fetal effects occurred. We conclude that low-dose dopamine produces a significant increase in urine production with resolution of oliguria in severe preeclampsia.

Dopamine and new dopamine analogs: receptors and clinical applications

Division of dopamine (DA) receptors and alpha- and beta-adrenoceptors into two subtypes provides a pharmacological basis for the clinical use of DA and new DA receptor agonists in anesthesia and critical care medicine. First, differential receptor activation explains why three distinct cardiovascular and renal responses can be obtained at low, medium, and high infusion rates of DA. Low infusion rates, in which DA1 and DA2 receptors are activated, are being increasingly used to improve renal perfusion and to treat oliguric states. The medium dose range (activation of beta1-adrenoceptors) is used for treatment of heart failure. The high dose range (activation of alpha-adrenoceptors) is used for treatment of shock. Second, selective DA1 and relatively selective DA2 agonists and agonists with different combinations of DA and receptor activity other than DA have been synthesized and are being investigated for the treatment of congestive heart failure and hypertension. Some of these compounds could have advantages over DA for acute therapy. Future availability of these drugs in anesthesia and critical care settings will depend to a great extent on input from anesthesiologists concerning potential new uses and willingness to conduct clinical investigations.

Augmentation of renal blood flow and sodium excretion in hypertensive patients during blood pressure reduction by intravenous administration of the dopamine1 agonist fenoldopam

Activation of dopamine1 (DA1) receptors relaxes vascular smooth muscle, especially in the renal vascular bed. Fenoldopam, the first selective DA1-receptor agonist that can be administered to man, was infused intravenously in 17 patients with essential hypertension (mean blood pressure 152/101 mm Hg). It reduced blood pressure in a dose-dependent fashion at doses between 0.025 and 0.5 microgram/kg/min and the antihypertensive effect was sustained during 2 hr infusions. In 10 patients studied during free-water diuresis, fenoldopam increased renal plasma flow by 42%, glomerular filtration rate by 6%, and sodium excretion by 202%, while lowering mean arterial pressure by 12% (all p less than .05). Similar promotion of sodium excretion was observed during blood pressure reduction in six additional patients studied without water loading. Pronounced enhancement of renal function in spite of blood pressure reduction suggests that fenoldopam might have a special role in the treatment of patients with hypertension and renal impairment.

The prevention of renal impairment in patients undergoing orthotopic liver grafting by infusion of low dose dopamine

Administration of low dose dopamine (2.0 micrograms/kg/minute) begun before surgery in patients undergoing liver transplantation decreases the incidence of postoperative renal impairment. Thirty-four consecutive patients in the Cambridge/King's College Hospital liver transplantation series were studied. Nineteen patients (21 transplant operations) received prophylactic low dose dopamine throughout the operative and early postoperative period, while 15 patients (15 transplant operations) received dopamine only when clinically indicated for incipient renal failure or as an inotropic agent. In the prophylactic dopamine group, only two transplant operations (9.5%) were complicated by renal impairment, whereas in the other group, 10 patients (67%) developed renal impairment (p = 0.001); of these, four developed acute renal failure (27%). Comparison of seven pairs of patients, matched for age, sex, diagnosis, operative blood loss and operative hypotension (one group receiving dopamine, the other not), revealed a significantly higher urine output in the first 24 hours and creatinine clearance 24-48 hours after surgery (p less than 0.05) in those treated prophylactically. In view of these findings, we would recommend that consideration be given to the prophylactic use of dopamine in patients undergoing orthotopic liver transplantation.

Pharmacology and therapeutic use of low-dose dopamine

The renal pharmacologic effects of intravenous dopamine in doses of 0.5-3.0 micrograms/kg/min include increases in renal blood flow, glomerular filtration rate, solute excretion, and urine flow. Clinical studies revealed that low-dose dopamine can reverse oliguria, but these studies were poorly controlled, were confounded by the use of other diuretics, had small patient populations, and often did not evaluate mortality or long-term renal function. When used in low doses, side effects are rarely seen. Because of dopamine's effect on hepatic and renal function, changes in drug clearance may occur. Low-dose dopamine may be considered in the early course of oliguric patients; however, specific advantages over other diuretic therapy have not been established.

Effect of haloperidol on dopamine-induced increase in renal blood flow

Increasing renal blood flow (RBF) by the administration of low-dose dopamine is one mechanism to increase urine output in oliguric patients. This response is mediated in part by stimulation of dopaminergic receptors in the kidney, which could be attenuated by the dopamine blocker haloperidol. We evaluated this interaction by administering both drugs in clinically used doses to six anesthetized mongrel dogs. A dopamine regimen of 2.5 micrograms/kg/min significantly increased RBF along with cardiac output and stroke volume. Simultaneous administration of haloperidol 50 micrograms/kg iv did not influence the ability of low-dose dopamine to increase RBF. Although haloperidol is an antagonist of dopaminergic receptors, the increase in RBF associated with low-dose dopamine is maintained when intravenous haloperidol is concurrently administered to dogs.

Effect of low-dose dopamine on the pharmacokinetics of tobramycin in dogs

Low-dose dopamine or a placebo was given to six healthy mongrel dogs, each receiving tobramycin at 2.0 mg/kg on consecutive days in a randomized crossover fashion. Dopamine increased the total and renal clearances and elimination rate constant of tobramycin by 12.5, 20, and 25.9%, respectively, suggesting that low-dose dopamine increases the clearance of tobramycin in dogs primarily through renal mechanisms.

[Acute renal failure after extracorporeal circulation with aortic counterpulsation in surgically treated patients]

In a series of 604 adults operated on for cardiac surgery with cardiopulmonary bypass (CPB), 21 (3.5%) underwent circulatory assistance by intra-aortic balloon pump (IABP); in 5 of them (24%), acute renal failure (ARF) was observed. ARF occurred in only 26 (4.4%) of the other patients who did not require IABP. Evolution of ARF and its factors were therefore investigated in those patients having received IABP. ARF was defined as serum blood urea nitrogen (BUN) greater than or equal to 16 mmol X 1(-1), urinary urea/BUN less than 10, creatinine clearance less than 40 ml X min-1 X 1.73 m-2. Some perioperative features were compared between patients with postoperative ARF and those without ARF. ARF occurred in the 5 patients with IABP during, or immediately after, weaning from IABP. ARF was more frequent in patients operated on for mechanical complications of myocardial infarction with a significant more severe haemodynamic status. They had significantly longer CPB and aortic clamping times. The prognosis depended on the cardiac failure and not on the ARF. In patients with mechanical complications of infarction, early IABP seemed to be the predominant preventive measure. Other therapeutic implications are suggested, particularly the use of dopamine (1 to 3 micrograms X kg-1 X min-1) because of its renal vasodilating action which can contribute to the maintenance of urinary flow.

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.

Resuscitation in acute haemorrhage

While some of the details of resuscitation of the bleeding patient remain contentious, the basic principles are clear. Adequate resuscitation implies the prompt restoration of tissue oxygenation by achievement and maintenance of airway patency, adequate ventilation, cardiac rhythm and intravascular volume. The choice of fluid for primary resuscitation is considerably less important than the care with which it ought to be administered. The volume of fluid required for primary resuscitation varies and there is no well-defined endpoint against which to titrate fluid resuscitation. However, as the complications and mortality of shock are related to the degree and the duration of shock, definitive (usually surgical) intervention should be undertaken early if the clinical features of shock cannot be readily reversed or if the maintenance of clinically adequate perfusion cannot be achieved with the administration of less than 200 ml of fluid per hour.

Haemodynamic comparison of dopamine and dobutamine in normovolaemic and hypovolaemic dogs

The haemodynamic effects of dopamine and dobutamine in doses of 1-106 micrograms/kg/min were compared in dogs, first in the normovolaemic state and then after bleeding (10 ml/kg). In normovolaemia, dopamine caused a dose-dependent rise in systolic, mean and diastolic aortic pressures, while dobutamine caused a rise only in systolic pressure. In hypovolaemia, a rise in all three aortic pressures, was caused by both drugs, but to a lesser extent by dobutamine. Heart rate and cardiac output were similarly increased by both drugs, as was pulmonary artery pressure with high doses, in both states. Renal blood flow and diuresis increased in the middle-dose area. Both inotropic drugs caused an elevation in Paco2 and a drop in Pao2 and O2-saturation in both normovolaemia and hypovolaemia. The results agree with current opinion on the dose-dependent alpha-sympathomimetic action of dopamine and the relatively pure beta-action of dobutamine.

Anaesthesia for the patient with impaired renal function

Patients with renal disease are at risk of further deterioration of renal function and acute tubular necrosis when subjected to anaesthesia and surgery. Optimal fluid loading and careful selection of anaesthetic techniques and agents, appropriate monitoring and the use of mannitol and dopamine assist in the maintenance of renal blood flow and help preserve renal function in these patients. In association with renal failure, physiological changes in other systems result in reduced oxygen supply to the tissues, metabolic disturbances, impairment of the coagulation and immune defence mechanisms and an increased risk of cardiac and cerebrovascular catastrophe. Although many anaesthetic techniques including regional analgesia may be used successfully in these patients caution with most drugs, especially pethidine, phenoperidine, suxamethonium and all non-depolarising neuromuscular relaxants is recommended. Of the volatile anaesthetics currently available, halothane is the agent of choice. Oxygen therapy and close monitoring of cardiorespiratory function are necessary postoperatively.

Concepts in the pharmacologic and nonpharmacologic support of cardiovascular function in critically ill surgical patients

The critically ill surgical patient requires close clinical, biochemical, and hemodynamic monitoring to define the right timing as well as the proper type of therapeutic intervention. Although many factors are available for monitoring, O2 delivery and extraction are two of the most important, since the enhanced metabolic demands of the stressed patient dictate a need to maintain greater than normal values to ensure survival. In other situations, primary therapy of the blood pressure, the PCWP, or other indices may take temporary precedence in the choice of therapeutic agents. Regardless of the means used to optimize O2 delivery, scrutiny of the consequences of therapy is equally important. Above all, any therapeutic intervention does not negate the need to treat the primary underlying process expeditiously.