Implementation of selective digestive decontamination in the intensive care unit: a word of caution

flow (RBF), renal vascular resistance (RVR), filtration fraction (FF), renal oxygen extraction (RO2Ex) and renal extraction of PAH, which was described in our paper, may not necessarily be ascribed to dopamine itself but to spontaneous fluctuations and time-dependent fluctuations of renal variables, as post-operatively, there are . . . ‘a great number of physiologic variations: changes in cardiac output, in systemic vascular resistance, haemoglobin level, volume loads, use of blood products and vasoactive drugs, among others’. First of all, we would like to stress that neither blood products nor vasoactive drugs (other than dopamine) were given during the experimental procedure. If the patient was unstable, he/she was not included in the study. We agree, however, that one major limitation of our study was the lack of a control group, not receiving dopamine, that could control for these potential time-dependent spontaneous fluctuations of the renal variables, which we also discussed at length in our paper. On the other hand, data on renal and systemic haemodynamics, as well as on renal function and oxygen metabolism, obtained during the two control periods before the start of dopamine infusion, did not differ significantly, but even more importantly, all data on renal variables returned to baseline after discontinuation of dopamine infusion. This suggests, at least to us, that the changes in RBF, RVR, FF, RO2Ex and renal extraction of PAH, which we observed during dopamine infusion, were caused by dopamine itself and not by changes in baseline conditions during the experimental procedure. S. E. Ricksten B. Redfors