And hemolysis goes on: ventricular assist device in combination with veno-venous hemofiltration

Ventricular Assist Device (VAD) is an accepted treatment as a bridge to cardiac transplantation, and may be of help in patients as destination therapy for end-stage cardiac failure. The low output state associated with end-stage cardiac failure predisposes patients to renal dysfunction and the need for short-term renal support. The use of cardiopulmonary bypass for VAD insertion, VAD, and hemofiltration expose the blood to mechanical trauma and activated inflammatory cascades that can result in hemolysis. This produces free hemoglobin, a known nephrotoxin; this is a further renal insult. This study assesses the effect of VAD alone and in combination with continuous veno-venous hemofiltration (CVVHF) on hemolysis.

From July 1999 to December 2000, Thoratec VAD was used in 11 patients. Nine (all males) were included in this study as all had laboratory profiles. Hemolysis was quantified by plasma free hemoglobin (PFHb) and hydroxybuterate dehydrogenase (HBD) levels measured daily, defined as PFHb level greater than 40 mg/L and HBD greater than 250 IU/L. Data relate to the following time intervals while the VAD was still in situ: T1 = 24 hours post-VAD insertion, T2 = 24 hours post-CVVHF start, T3 = 48 to 72 hours with the same CVVHF circuit, T4 = 24 hours post-stopping of CVVHF, and T5 = CVVHF off for over 48 hours. The mean (SD) PFHb levels were 19.6 (10.9) at T1, 31.7 (0.6) at T2, 93.7 (16.4) at T3 (p < 0.05), 32.5 (20.9) at T4, and 14.2 (3.8) at T5 (p < 0.05). These changes were paralleled by the mean (SD) HBD levels: T1 = 1,337 (616), T2 = 2,025 (509), T3 = 2,676 (1,170) (p < 0.05), T4 1,780 (618), and T5 = 1,310 (436).

Thoratec VAD was associated with a mild degree of hemolysis. This was worsened by concomitant use of CVVHF. The effect was accentuated if the same CVVHF circuit was used for over 48 hours but was reversible within 24 hours of stopping the hemofilter.