8 Hydrostatic pressure is determined by the blood pressure in the filtering device, generated by either the patient’s blood pressure or an extracorporeal pump plus the suction occurring in the ultrafiltrate compartment. Ultrafiltration is the production of plasma water from whole blood across a semipermeable membrane (hemofilter) in response to a transmembrane pressure gradient generated by the hydrostatic pressures in the blood and in the filtrate compartments and the oncotic pressure produced by plasma proteins. A modified ultrafiltration device has overcome these limitations. 8 The application of this technology has been limited by the need for high flow rates, large extracorporeal blood volumes, and large-bore central venous catheters. 3–7 Ultrafiltration is an alternative method of sodium and water removal that safely improves hemodynamics in HF patients. Furthermore, loop diuretics may be associated with increased morbidity and mortality due to deleterious effects on neurohormonal activation, electrolyte balance, and cardiac and renal function. 3 Unresolved congestion may contribute to high re-hospitalization rates. However, the effectiveness of loop diuretics declines with repeated exposure. Intravenous loop diuretics induce rapid diuresis that reduces lung congestion and dyspnea. Guidelines recommend that therapy for HF patients be aimed at achieving euvolemia. 1,2 Hypervolemia contributes to HF progression and mortality. In addition, the surface-assembled charged HPGs effectively suppress the attachment and accumulation of foulants having the same charge due to electrostatic repulsion and improved surface hydrophilicity.In the US, 90% of the one million annual hospitalizations for heart failure (HF) are due to volume overload.
As expected, zeta potential results disclose that the differently charged HPGs provide the desired electrical properties to the membrane surface. The surface hydrophilicity improves upon assembly of the hydrophilic charged HPGs. The combined results for 1H NMR, FT-IR, and XPS results show that the charged HPGs are successfully synthesized and bound to the surfaces of the PVDF membrane.
We prepare three types of charged HPGs, i.e., neutrally charged HPGs without end group modifications, positively charged HPG with quaternary ammonium groups, and negatively charged HPG with sulfonate groups. The native HPGs are neutrally charged polymers with a lot of hydroxyl end groups that can be modified with specific charges. The charge-modified membranes are fabricated through surface assembly of various charged hyperbranched polyglycerols (HPGs), which act as anti-fouling agents. We develop a charge-modified PVDF UF/MF membrane that restricts membrane fouling derived from charged water contaminants.
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