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(Circulation. 2008;118:e675.)
© 2008 American Heart Association, Inc.

Correspondence

Letter by Lema et al Regarding Article, "Renal Vasodilatory Action of Dopamine in Patients With Heart Failure: Magnitude of Effect and Site of Action"

Guillermo Lema, MD; Roberto Canessa, MD

Department of Anesthesiology, Pontificia Universidad Católica de Chile, Santiago, Chile

Jorge Urzúa, MD

Universidad Santo Tomás, Santiago, Chile

To the Editor:

I have read with great interest the article by Elkayam et al¹ regarding renal effects of dopamine in a group of patients with heart failure. I would like to add some comments to the discussion.

The vasodilatory effects of dopamine have been reported previously.² A debatable "renal protection effect" has been erroneously attributed to this finding.

The study shows vasodilatory effect of dopamine, with an increase in renal blood flow measured by Doppler technique. However, the authors do not find significant differences in renal blood flow when doses greater than 2 µg · kg^–1 · min^–1 are infused. They discuss whether the small number of patients undergoing the study may explain this finding.

This could be true; however, there could be another explanation for this finding. In fact, an important intersubject variability on plasma levels of dopamine has been described. A study published by MacGregor et al³ showed in healthy normal subjects that the plasma concentration of dopamine varied from 12 300 to 201 500 ng/L after 10 µg · kg^–1 · min^–1 of dopamine. When patients received 3 µg · kg^–1 · min^–1, concentration varied from 1800 to 18 300 ng/L. They conclude that in a homogenous population, a dopamine dose based only on body weight may give unpredictable plasma levels and clinical effects. Compartmental pharmacokinetic models may explain this behavior (changes of dopamine distribution and metabolism).

There is no reason to think that patients such as those studied in the work by Elkayam et al¹ would behave differently. Clinical effects and the variability among patients may depend on the plasma levels and its subsequent action on the different known receptors.

	Acknowledgments

 
Source of Funding

This work was funded by grant No. FONDECYT 1030645–2003.

Disclosures

None.

	References

Top References

 
1. Elkayam U, Ng TM, Hatamizadeh P, Janmohamed M, Mehra A. Renal vasodilatory action of dopamine in patients with heart failure: magnitude of effect and site of action. Circulation. 2008; 117: 200–205.[Abstract/Free Full Text]

2. Lema G, Urzua J, Jalil R, Canessa R, Moran S, Sacco C, Medel J, Irarrazaval MJ, Zalaquett R, Fajardo C, Meneses G. Renal protection in patients undergoing cardiopulmonary bypass with preoperative abnormal renal function. Anesth Analg. 1998; 86: 3–8.[Abstract]

3. MacGregor DA, Smith TE, Prielipp RC, Butterworth JF, James RL, Scuderi PE. Pharmacokinetics of dopamine in healthy male subjects. Anesthesiology. 2000; 92: 338–336.[CrossRef][Medline] [Order article via Infotrieve]

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