Microcirculatory perfusion derangements during continuous hemofiltration with fixed dose of ultrafiltration in stabilized intensive care unit patients.

Acute kidney injury (AKI) is a well-known complication in critically ill patients. Little is known about the timing and the ultrafiltration dose after initial resuscitation. In vivo microscopy of the microcirculation has been suggested as alternative for the assessment of volume status. Previous studies contribute to the understanding that intravascular hypovolemia is reflected by microcirculatory blood flow changes not detected by conventional methods. The aim of our study was to assess microcirculatory blood flow changes during negative fluid balance ultrafiltration in patients with oliguric AKI.Patients with oliguric AKI on renal replacement therapy were included after hemodynamic stabilization. Target was a predefined negative fluid balance; subsequently, a stepwise decrease in amount of substitution fluid was achieved. The data were recorded at baseline and after each change.Fifteen patients were included in the study. Microcirculatory blood flow index did not change significantly between baseline and endpoint (2.90 [2.87-3.00] vs 2.90 [2.75-3.00], P=.57). During treatment, heart rate decreased from 96 (80-111) to 94 (79-110) beats per minute (P=.01), without a significant change in mean arterial blood pressure (80 [68-95 mm Hg] vs 79 [65-91 mm Hg], P=.5).Microcirculatory blood flow is not altered by reduced substitution during renal replacement therapy.