Author + information
- Giancarlo Marenzi, MD⁎ ( and )
- Nadia Aspromonte, MD
- ↵⁎Centro Cardiologico Monzino, IRCCS, Via Parea 4, 20138 Milan, Italy
We read with great interest the recent paper by Patarroyo et al. (1) regarding the possible lack of association between hemodynamic and renal function improvement in refractory heart failure patients treated with slow continuous ultrafiltration (SCUF).
The authors pointed out that their findings refuted the hypothesis that hemodynamic improvement with SCUF can translate into direct renal improvement and cautioned the promise of potential benefit of SCUF in the setting of severe refractory heart failure. However, we believe that 2 additional reasons, rather than SCUF treatment per se, could explain their results.
First, in this study, patients had possibly already developed acute kidney injury before SCUF initiation, as suggested by the increase in serum creatinine from 1.9 ± 0.8 mg/dl to 2.2 ± 0.9 mg/dl. Thus, the further creatinine increase (2.4 ± 1 mg/dl) after SCUF, and the high need for transition to renal replacement therapy, might only reflect the spontaneous ongoing acute renal injury started before SCUF. Conversely, we cannot exclude that SCUF-induced hemodynamic improvement have hampered the negative clinical and prognostic trajectory of such an acute renal event.
Second, a SCUF-induced hypovolemia due to an excessive, or excessively fast (when compared with patients' plasma refilling rate capacity), fluid removal, with consequent further renal injury, seems to emerge from this study. Indeed, while hematocrit did not change (from 31 ± 4.3% to 31 ± 4%; p = 0.6), protein total concentration significantly increased (from 5.9 ± 1.2 g/dl to 6.6 ± 0.6 g/dl; p = 0.006) during SCUF. Changes in plasma volume during SCUF may be monitored by evaluating changes in hematocrit fraction (in the absence of bleeding and blood transfusion) that should parallel plasma protein changes (2,3). Thus, when plasma volume remains stable, no net gain or loss of intravascular proteins should be observed. In the present study, the divergent behavior of hematocrit (unchanged) and proteins (increased) suggests a decrease in blood volume, with a concomitant bleeding that may have hindered hematocrit increase associated with blood volume reduction.
Therefore, it is not surprising that a too aggressive and rapid depletion of intravascular volume in patients with acute kidney injury could be associated with lack of renal function recovery. A more prudential, even if partial, dehydration by SCUF should be targeted, or another kind of renal replacement modality chosen, in these patients and, particularly, in those—like probably many in this study—with an impending or overt cardiogenic shock (average cardiac index was 1.8 [range: 1.48 to 2.25] l/min/m2). With these clinical and hemodynamic conditions, no immediate recovery in kidney function is likely after SCUF, despite the achievement of a significant hemodynamic improvement.
- American College of Cardiology Foundation
- Patarroyo M.,
- Wehbe E.,
- Hanna M.,
- et al.
- Marenzi G.,
- Lauri G.,
- Grazi M.,
- et al.