Paolo M. Ghezzi

Choosing new adsorbents for endogenous ultrapure infusion fluid: performances, safety and flow distribution.

Adsorption may notably contribute to the removal of uremic toxins and to the efficiency of hemodialysis. We examined different uncoated stationary matrixes, charcoals and synthetic resins to establish their adsorptive capacities in relation to low (urea, creatinine) and high molecular weight (β2-microglobulin, myoglobin) compounds in in vitro conditions (steady state and flow-through) using isotonic solutions or uremic ultrafiltrate. Trace metal, particle release analyses and scanning electron microscopy of different adsorbents were performed. Dynamic flow-distribution studies were made using 99Technetium and analysing the different regions of interest by single head γ-camera. We show that adsorbents may differ greatly as to their adsorptive capacity depending on flow rate, nature, and total mass of the compounds to be removed from the ultrafiltrate. These studies suggest a methodological approach for screening stationary matrixes for possible application in hemodialysis.

Membranes for hemodialysis

The initiation of renal replacement therapy in chronic uremia coincides with the evolution and subsequent progression of renal disease. The decision as to the appropriate starting moment for the substitution program is still the subject of much discussion. Although specific biochemical parameters (such as the level of plasma creatinine) have been suggested to guide the decision to begin therapy, each patient must be evaluated on an individual basis; whilst specific guidelines may be helpful, they must be considered in conjunction with a large number of additional factors. Some patients may appear well, but may have high levels of creatinine, while others may have much lower creatinine levels, but nevertheless demonstrate classic signs of the uremic syndrome such as nausea, vomiting, progressive anemia, electrolytic disorders, acid—base disequilibrium or neuropathy.

Effect of on-line hemodiafiltration with endogenous reinfusion (hfr) on the calcium-phosphorus metabolism: medium-term effects

Aim The purpose of the study was to examine the effect of hemodiafiltration with endogenous reinfusion (HFR) compared to hemodialysis (HD) on 28 uremic patients with secondary hyperparathyroidism (2HPT) but positively selected for good and stable control of phosphatemia in order to evaluate the independent effects of dialysis treatments on bone turnover metabolism. Methods: The study was divided into 3 periods of observation: a) HD for three months; b) HFR for three months; c) HFR for a further 3 months. We analysed the trend of: whole PTH, 1–84 PTH, 7–84 PTH, alkaline phosphatase and its bone isoenzyme, total and ionised calcium, phosphatemia, dose of phosphate binder agents, β2-microglobulin, CRP. All the variations found were evaluated through mean values ± SD, t-tests, multivariate analysis. Results We observed a deceleration in bone turnover characterized by a reduction of the total and bone alkaline phosphatase (IU/mL) from 92.3 ± 82.8 and 35.8 ± 49.8 at the end of HD to 63.4 ± 23.9 and 16.0 ± 8.7 at the end of HFR, respectively, and 1–84 PTH from 317.5 ± 264.6 pg/mL at the end of HD to 287.5 ± 258.9 pg/mL at the end of the 3rd month of HFR. β2-microglobulin was reduced from 32.9 ± 16.1 mg/L at the end of HD to 26.4 ± 8.1 mg/L already at the end of the first three months of HFR. CRP was reduced from 2.5 ± 2.6 mg/dL at the beginning of the study to 1.3 ± 1.7 mg/dL at the end of HFR. There were no differences with regard to: dialytic efficiency, nutritional status, calcemia, phosphatemia (maintained in the K-DOQI range for the entire duration of the study), also thanks to more careful use of phosphate chelating agents. Conclusion We are of the opinion that HFR - essentially thanks to the use of ultrapure endogenous infusate - induces a deceleration in bone turnover due to 2PHT. In addition, phosphate substraction in HFR is better compared to HD, thanks to the improvement of the anti-inflammatory conditions by removing the cytokines harmful to bone metabolism and excluding a priori the negative effects related to hyperphosphatemia. (Int J Artif Organs 2006; 29: 1042–52)

Adsorption in Extracorporeal Blood Purification: How to Enhance Solutes Removal Beyond Diffusion and Convection

Uremic syndrome is linked to a plethora of uremic toxins circulating in the body in ESRD patients. Their overall spectrum is partly or entirely unexplored despite the need to urgently define the specimens and the patho-physiology beyond their high blood levels to address new or more selective removal strategies. It is generally accepted that convective hemodialysis is the best choice to remove large part of the molecular spectrum, even though it is not fully demonstrated its superiority in terms of clinical outcomes. Then, transport mechanisms can benefit from maximizing all the physi‐ co-chemical principles including diffusion for small solutes, convection for middle mole‐ cules and adsorption for large molecular size uremic toxins. The latter has not been fully adopted in hemodialysis and this transport mechanisms is limited to the intrinsic capability of dialysis membrane to adsorb macromolecules while transporting solutes by diffusion and/or convection. However, poorly has been explored about the use of sorbents to enhance the solute removal in hemodialysis. The purpose of this chapter is to summarize the main contributions of so far published clini‐ cal and technical experiences. The chapter will be structured as follow: first we introduced a summary of the basic princi‐ ples of solutes transport and relative contribution of the different mechanisms to the overall