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J Am Coll Cardiol, 2005; 46:2052-2053, doi:10.1016/j.jacc.2005.09.014
(Published online 8 November 2005). © 2005 by the American College of Cardiology Foundation |
,*,
Division of Cardiovascular Disease, Department of Medicine, University of Alabama, Birmingham, Alabama
Department of Medicine, Birmingham Veterans Administration Medical Center, Birmingham, Alabama
* Reprint requests and correspondence: Dr. Robert C. Bourge, Professor and Director, UAB Division of Cardiovascular Disease, 311 THT, 1900 University Boulevard, Birmingham, Alabama 35294 (Email: bbourge{at}uab.edu).
The concept of the extracorporeal removal of fluid with UF has been reported for over 50 years (7). In the mid-1970s, the use of pump-driven extracorporeal UF was described (8), and not long thereafter its use was described in a cardiac patient (9). By the mid-1980s, the first reports of the use of UF in patients with heart failure were published (10–12). These studies used a large cumbersome hemodialysis machine with blood removal accomplished by a central venous line in a small numbers of markedly volume-overloaded patients with clinical evidence of diuretic resistance. A unique and interesting characteristic of the new device used in the two current studies (System 100, CHF Solutions, Minneapolis, Minnesota) is that it is smaller, portable, and less invasive, requiring only a peripherally inserted 16G 35-cm withdrawal catheter and a regular 16G or 18G 3.5-cm infusion catheter in a major vein system, usually the brachial-cephalic system (13). Ultrafiltration removes water and nonprotein-bound small- and medium-molecular-weight solutes through a semipermeable membrane when hydrostatic pressure, generated by blood pressure or an external blood pump, exceeds oncotic pressure. The fluid removal rate is set by the treating physician and can range between 100 and 500 ml/h. The device does not require an ICU setting or specialized nursing or technical oversight. Ultrafiltration does not seem to change the creatinine or urea concentration so should not be confused with hemodialysis. Ultrafiltration results in a decrease in the ventricular filling pressures without significant changes in renal function (14).
Costanzo et al. (5) report their experience in a small pilot study with early initiation of UF, within hours of admission, in 20 patients with ADHF manifested by volume overload, with clinical evidence of renal insufficiency or somewhat loosely defined diuretic resistance, testing the hypothesis that UF could result in early euvolemia and early discharge (
3 days) without adverse effects. UF was continued until the patients achieved relief of their presenting symptoms of congestion. The removal of fluid was aggressive, with an average fluid removal of 8.6 ± 4.2 l and a mean decrease in weight of approximately 6 kg at discharge. As expected with the removal of fluid and solute, clinical signs and symptoms and laboratory indices of hypervolemia improved by discharge. The improvement lasted for up to 90 days after initiation of UF; however, loop diuretics use increased with admission and remained higher at all follow-up periods (not statistically different, given the small number of patients in this nonrandomized evaluation). Importantly, there was no apparent deterioration in parameters of renal function, hypotension, or hyperkalemia.
In another study in the Journal, Bart et al. (6) report the results of a randomized but nonblinded trial of usual care vs. usual care and UF in 40 patients admitted with ADHF and evidence of volume overload. Patients in the UF group received an 8-h UF treatment in addition to usual care; however, diuretics were withheld during UF. Dyspnea and CHF symptoms improved in both groups at 24 h, with a slightly greater improvement at 48 h in the UH group. The average volume removal was higher in the UF group at 24 h (4.6 vs. 2.8 l) and 48 h (8.4 vs. 5.3 l). However, weight loss, a surrogate of adequate diuresis and net fluid loss, which was the primary endpoint of the study, was not significantly different between groups. There was one death in the UF group during the 30-day follow-up. Adverse events included catheter infection which required 4-week course of IV antibiotics, and there was a small but significant drop in the hemoglobin in the treatment group, the opposite of what could be expected during aggressive diuresis. The fact that UF was limited to a single 8-hour session may have contributed to the lack of significant weight loss, and the net fluid loss is not as impressive as in the study by Costanzo et al. (5), where UF was continued until patients reached clinical evidence of euvolemia. The slight decrease in the hemoglobin may have been an effect of this therapy, which the authors theorize as related to bleeding complications from the use of heparin, a complication from line placement, or retention of blood by the device.
From these two studies, we can conclude that UF is probably safe and results in a fast and effective method of fluid and salt removal with a resultant improvement in the symptoms of congestion in patients with CHF and volume overload. Another important effect of UF is a decrease in neurohormonal activity, manifested by declining levels of renin, norepinephrine, and aldosterone, as opposed to the effects seen with diuretic therapy (15). It should be noted that UF is not a substitute for dialysis in patients with renal insufficiency, metabolic abnormalities such as acidosis, uremia, or heart failure resistant to diuresis. The physical properties of the device do not allow removal of waste products.
As with any new treatment modality, there are several questions left unanswered in its early adaptation, despite the approval of the device by the U.S. Food and Drug Administration. What type of patient benefits the most from this intervention? Could there be additional unexpected side effects in addition to the slight drop in hemoglobin and the potential of a severe intravenous line infection? Are the beneficial effects, such as the improvement in volume status and decreases in neurohormonal activation and serum BNP, really "long-lasting"? Fortunately, a large multicenter randomized trial is currently under way in which 200 patients with ADHF manifested by volume overload will be randomized to either usual care or usual care plus UF. Although we cautiously welcome the addition of this device-based therapy to effectively improve volume overload and symptoms in patients with congestive heart failure, the results of larger randomized trials should be evaluated carefully, with special attention to adverse effects and the incremental total cost of such therapy.
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  Ultrafiltration for Acute Decompensated HF? Journal Watch Cardiology, January 19, 2006; 2006(119): 1 - 1. [Full Text]
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