Hemodiafiltration: the addition of convective flow to hemodialysis

Abstract

Hemodiafiltration (HDF) combines both hemofiltration (HF) and hemodialysis in the same procedure. It was initially performed in adults in 1977, and later used in children in the early 1980s. The use of HDF allows a determined convective dialysis dose to be combined with the conventional urea dialysis dose. The dialysis session is better tolerated as a result of the effects of hemofiltration. On-line HDF, i.e., substitution fluid prepared from ultrafiltration of the ultrapure dialysate, can be performed safely due to recent advances in modern technology. However, despite interest and feasibility in children, the majority of pediatric dialysis units across the world still perform hemodialysis using highly permeable membranes, allowing back filtration in the filter and therefore a degree of convective flow, i.e., internal hemodiafiltration. In some countries, government restrictions prohibit the use of on-line hemodiafiltration, (such as the FDA recommendations in North America), and therefore it should not be used in these circumstances.

Innovative strategy with potential to increase hemodialysis efficiency and safety

“…Thus, technical improvements in HD have primarily focused on the development of biocompatible antioxidant dialyzer membranes45, and the modification of dialysates67. Also, efforts have been done to increase the efficiency and safety of HD using convective therapies8, ultrapure dialysate9 and intelligent therapy control with advanced dialysis machines10. Current renal substitution therapy with HD or home-based peritoneal dialysis (PD) has been the only successful long-term ex vivo organ substitution therapy for sustaining life11, while technical advances directed at improving clinical outcomes in both HD and PD have been limited.…”

The interdialytic weight gain: a simple marker of left ventricular hypertrophy in children on chronic haemodialysis

“…To achieve euvolaemia many nephrologists prescribe high ultrafiltration rates [17], especially if the patient appears to tolerate it [3,8]. A patient's tolerance to a higher ultrafiltration rate depends on many factors, including maintaining normal haemoglobin levels, the use of bicarbonate dialysate buffe r, h i g h e r d i a l y s a t e s o d i u m c o n c e n t r a t i o n [ 5 ] , haemodiafiltration technology [18], ultrafiltration or sodium profiling, lowering dialysate temperature and on-line blood volume monitoring [9,10], and has dramatically improved over the last decades [6]. Nonetheless, even a well-tolerated high ultrafiltration rate, such as >1.24 % body weight loss per hour in adults, is associated with greater mortality [19].…”

“…HDF is the addition of a determined convective volume to HD [18], thereby allowing for blood purification combining diffusive mass transport of small uraemic toxins and convective mass transfer of larger middle-molecular weight uraemic toxins. The total convective volume achieved over a HDF session is the sum of the prescribed weight loss and the predetermined ultrafiltration flow of blood, with ultrafiltration replaced by an equal volume of substitution fluid in order to achieve a large convective volume.…”

Nocturnal intermittent hemodialysis

“…Based on their clinical experience, Fischbach et al reported that high-efficiency HDF also had beneficial effects in the pediatric setting [44]. Thumfart et al combined NIHD with HDF (NHDF) in a prospective cross-over study [45] and found that serum phosphate concentration was significantly reduced in both intensive dialysis modalities, with NIHD lowering the phosphate concentration by 0.43 mg/dl and NHDF lowering it by 0.5 mg/dl despite the discontinuation of phosphate binders [45].…”