What is the effect of dopamine on vasodilation, particularly in improving renal perfusion?

From the Guidelines

Dopamine has minimal beneficial effect on vasodilation for improving renal perfusion and is no longer recommended for this purpose in clinical practice. At low doses (<2 mg/kg/min i.v.), dopamine acts on peripheral dopaminergic receptors, causing vasodilation predominantly in the renal, splanchnic, coronary, and cerebral vascular beds, as noted in the European Heart Journal guidelines 1. However, the most recent and highest quality study, the 2016 Surviving Sepsis Campaign guidelines, strongly recommends against using low-dose dopamine for renal protection (strong recommendation, high quality of evidence) 1. This is because multiple clinical trials and meta-analyses have demonstrated that "renal-dose" dopamine does not prevent acute kidney injury, improve renal recovery, or reduce mortality in critically ill patients with impaired kidney function.

Some key points to consider:

• The physiological basis for this finding is that while dopamine can transiently increase renal blood flow and urine output, these effects do not translate to meaningful improvement in glomerular filtration rate or kidney function preservation.
• At higher doses (>5 mcg/kg/min), dopamine primarily activates alpha-adrenergic receptors, causing vasoconstriction that may actually worsen renal perfusion.
• For patients requiring vasopressor support with concerns about renal perfusion, norepinephrine is generally preferred as the first-line agent, with vasopressin sometimes added as a second agent, as suggested by the 2013 ACCF/AHA guideline for the management of heart failure 1.
• Volume resuscitation, treating the underlying cause of hemodynamic instability, and avoiding nephrotoxic medications remain the cornerstones of preserving renal function in critically ill patients, as emphasized in the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1.

From the FDA Drug Label

The drug also has been reported to produce dilation of the renal vasculature which is accompanied by increases in glomerular filtration rate, renal blood flow and sodium excretion.

The vasodilatory effects of dopamine are present, particularly in improving renal perfusion. Dopamine has been reported to produce dilation of the renal vasculature, which is accompanied by increases in glomerular filtration rate, renal blood flow, and sodium excretion 2.

• Key points:
  • Dopamine produces dilation of the renal vasculature
  • Increases glomerular filtration rate
  • Increases renal blood flow
  • Increases sodium excretion
• Clinical decision: Dopamine can be used to improve renal perfusion in patients with decreased renal function. However, the dosage should be adjusted according to the patient's response, and careful monitoring of urine output, blood pressure, and cardiac output is necessary 2.

From the Research

Vasodilatory Effects of Dopamine

The effect of dopamine on vasodilation, particularly in improving renal perfusion, has been studied in various clinical settings.

• Dopamine has been shown to improve renal blood flow, glomerular filtration rate, sodium excretion, and creatinine clearance, independent of its cardiac effects 3.
• Low-dose dopamine can decrease renal and systemic vascular resistance, suppress aldosterone secretion, and interact with atrial natriuretic factor, leading to improved renal perfusion 3.
• The use of low-dose dopamine has been beneficial in preserving renal function in cardiac surgery, vascular surgery, liver transplantation, contrast-induced nephropathy, hypertension, and pediatric patients 3.

Renal-Dose Dopamine

The concept of "renal-dose" dopamine refers to the use of low-dose dopamine (1-3 micrograms/kg per min) to augment renal blood flow and function.

• Renal-dose dopamine has been shown to increase renal blood flow, sodium excretion, and glomerular filtration rate in healthy humans and experimental animals 4.
• However, most studies in humans have not demonstrated prevention of acute renal failure in high-risk patients or improved outcome in those with established acute renal failure 4.
• The safety profile of dopamine in these settings has not been extensively defined, and it is known that the drug may precipitate serious cardiovascular and metabolic complications in the critically ill 4.

Mechanism of Action

The mechanism of action of dopamine on renal vasodilation involves the activation of dopamine receptors in the renal vasculature.

• Fenoldopam, a dopaminergic agonist, has been shown to produce dose-related increases in para-aminohippuric acid clearance, indicating increased renal blood flow 5.
• The increase in renal blood flow is accompanied by increases in urine volume, water, and solute excretion, with no change in glomerular filtration rate 5.
• The dopamine receptor antagonist metoclopramide attenuates the increase in para-aminohippuric acid clearance, suggesting that the renal vasodilatory effect of fenoldopam is mediated by dopamine receptors 5.

Clinical Implications

The clinical implications of the vasodilatory effects of dopamine on renal perfusion are significant.

• Dopamine may be useful in improving renal function in patients with heart failure, particularly at doses that do not affect blood pressure 6.
• The increase in renal blood flow appears proportionately larger than corresponding increases in cardiac output, suggesting a direct effect of dopamine on the renal vasculature 6.
• Further evaluation of the efficacy and safety of dopamine for improvement of renal function in hospitalized patients with heart failure is warranted 6.