Renal effects of low-dose dopamine in the critically ill

Objective

To examine the renal effects of low dose dopamine in patients receiving dopamine 2.5 μg/kg/min and no other vasoactive therapy.

Subjects

Critically ill but stable patients, median APACHE II 13 (range 8–26), with a pulmonary artery catheter placed to assist volume resuscitation

Design

Prospective study.

Methods

Optimal filling was assessed by left ventricular stroke work index (LVSWI) reaching a plateau with serial fluid challenges and recording the pulmonary artery wedge pressure at this optimal LVSWI. We endeavoured to maintain this pulmonary artery wedge pressure throughout the study. The study consisted of two periods of 2 h duration, 1 h was allowed between them for equilibration. Patients were maintained on volume replacement alone for the first period and then dopamine was infused at 2.5 μg/kg/min and continued for the second period. Blood samples were taken at the beginning and end of each period. Urine was collected over each 2 h period for the measurement of volume and calculation of creatinine clearance (C_Cr) and fractional sodium excretion (FE_Na). Cardiac output studies were also performed during each period.

Analysis

Renal parameters were compared using Wilcoxon signed rank test (stat view 4.5). Statistical significance was taken as a P value < 0.05.

Results

We studied 11 patients, none had to be withdrawn because of hypotension or increasing inotrope requirements.

Conclusion

The above data shows a statistically significant increase in urine volume with low dose dopamine.

Table