Hemodialysis shake-up on the front lines of the Covid-19 pandemic: the Treviglio Hospital experience.

The new coronavirus disease (Covid-19) pandemic in Italy formally started on 21st February 2020, when a 38-years old man was established as the first Italian citizen with Covid-19 in Codogno, Lombardy region. In a few days, the deadly coronavirus swept beyond expectations across the city of Bergamo and its province, claiming thousands of lives and putting the hospital in Treviglio under considerable strain. Since designated Covid-dialysis hospitals to centrally manage infected hemodialysis patients were not set up in the epidemic areas, we arranged to treat all our patients. We describe the multiple strategies we had to implement fast to prevent/control Covid-19 infection and spread resources in our Dialysis Unit during the first surge of the pandemic in one of the worst-hit areas in Italy. The recommendations provided by existing guidelines and colleagues with significant experience in dealing with Covid-19 were combined with the practical judgement of our dialysis clinicians, nurses and nurse's aides.

[Mixed hemodiafiltration]. / Emodiafiltrazione mista.

Mixed hemodiafiltration is a novel technique in which the traditional infusion modes of predilution and postdilution are carried out simultaneously in the same dialyzer to overcome the limits and risks of each and join their advantages. It is performed under the control of transmembrane pressure feedback, which constantly monitors blood and dialysate compartments and adjusts both the total infusion amount and its ratio in predilution and postdilution mode, in order to achieve the safest rheological and hydraulic conditions. The ensuing maximization of the convective fraction optimizes middle-molecule removal. The technical characteristics, method of application, and clinical results of mixed hemodiafiltration are described in this article.

Optimization of mid-dilution haemodiafiltration: technique and performance.

BACKGROUND: Mid-dilution haemodiafiltration (MD-HDF), reported as a highly efficient convective-mixed technique, has demonstrated serious drawbacks in relation to the high pressure originating inside the blood compartment of the filter during clinical application. This randomized crossover design study was planned to optimize the efficiency of the MD-HDF technique while reducing its inherent risks. METHODS: Fifteen patients on RRT were submitted in random sequence to standard and reverse MD-HDF under similar operating conditions. Efficiency in solute removal was evaluated by measuring urea (U), phosphate (P) and beta2-microglobulin (beta2-m), mean dialysate clearances (K(DQ)) and eKt/V. Blood and dialysate compartment pressures were monitored on-line during the sessions, and instantaneous hydraulic and membrane permeability indexes were calculated. RESULTS: During standard MD-HDF sessions, unlike with reverse MD-HDF, excessive blood inlet and transmembrane pressure prevented the planned infusion from being maintained. Resistance index and membrane permeability to water and middle molecules substantially improved with reverse MD-HDF. This resulted in higher beta2-m removal (221.3 +/- 81.3 versus 185.1 +/- 65.5 mg/session, P = 0.007). Phosphate removal was comparable, while U removal was greater with standard MD-HDF (K(DQ) 272 +/- 35 versus 252 +/- 29 ml/min, P = 0.002; eKt/V 1.63 +/- 0.23 versus 1.49 +/- 0.17, P = 0.005). CONCLUSIONS: This study demonstrated the ability of MD-HDF to remove significant amounts of medium-sized uraemic compounds and phosphate, but safe rheologic and hydraulic conditions were only maintained by carrying out treatments with the dialyser used in reverse configuration. For this purpose, the larger MD-220 dialyser ensured better tolerance together with higher middle molecules clearance, even though small molecule removal was slightly worsened. The results of this study may provide some insight into the complex interactions between pressures and flux within the original structure of MD-dialysers and help optimize the clinical application of the technique and reduce its risks.

Mixed-dilution hemodiafiltration.

Mixed-dilution hemodiafiltration (mixed HDF) controlled by the transmembrane pressure (TMP) feedback, improves the depurative capacity of the more traditional HDF techniques by fully exploiting the convective mechanism of small- and middle-molecular-weight solute removal. The feedback allows the TMP to be set and profiled from patient and operational parameters recorded online by the machine. It automatically adjusts the infusion ratio between predilution and postdilution at the maximum filtration fraction without reducing the total infusion/ultrafiltration rate and taking into account fl ow conditions, internal pressures and hydraulic permeability of the dialyzer, and their complex interactions and changes during the session. The application of the TMP profile, while avoiding dangerous hydrostatic pressures within the dialyzer and their negative effects, helps better preserve the permeability of the membrane with the effect of a significantly increased solute removal in a wide molecular range and with minimal protein leakage. In the light of the more recent observations in the literature, the high biocompatibility resulting from the use of synthetic membranes and ultrapure dialysate, combined with the enhanced removal of small- and middle-molecular-weight uremic toxins obtained with high-efficiency HDF, seems to be the best available strategy to prevent or delay the occurrence of long-term dialysis complications and to promote improved survival of dialysis patients. Preliminary results of its application indicate that TMP-modulated mixed-dilution HDF could be one of the most powerful strategies to achieve this goal.

New strategies in haemodiafiltration (HDF): prospective comparative analysis between on-line mixed HDF and mid-dilution HDF.

BACKGROUND: Improvement in the uraemic toxicity profile obtained with the application of convective and mixed dialysis techniques has stimulated the development of more efficient strategies. Our study was a prospective randomized evaluation of the clinical and technical characteristics of two new haemodiafiltration (HDF) strategies, mixed HDF and mid-dilution HDF, which have recently been proposed with the aim of increasing efficiency and safety with respect to the standard traditional HDF infusion modes. METHODS: Ten stable patients on renal replacement therapy (mean age 64.7 +/- 8.2 years) were submitted in randomized sequence to one mid-week session of mid-dilution HDF and one of mixed HDF with trans-membrane pressure feedback control. All sessions were carried out under similar operating conditions and involved monitoring pressure within the internal dialyser compartments and calculating the rheological and hydraulic indexes. Efficiency in removing urea, phosphate and beta2-microglobulin (beta2-m) was tested. RESULTS: In mixed HDF, safer and more effective flux/pressure conditions resulted in better preservation of the hydraulic and solute membrane permeability (mean in vivo ultrafiltration coefficient 36.9 +/- 3.9 vs 20.1 +/- 3.3 ml/h/mmHg) and ensured higher volume exchange (38.7 +/- 4.2 vs 35.3 +/- 6.5 l/session, P = 0.02) and greater efficiency in removing small and middle molecules (mean urea clearance: 274 +/- 42 vs 264 +/- 47 ml/min, P = 0.028; eKt/V: 1.78 +/- 0.22 vs 1.71 +/- 0.26, P = 0.036; mean phosphate clearance: 138 +/- 16 vs 116 +/- 45 ml/min, P = 0.2; mean beta2-m clearance: 81 +/- 13 vs 59 +/- 13 ml/min, P = 0.001). CONCLUSIONS: Mixed HDF was the most efficient technique in the highest range of safe operating conditions. In mid-dilution HDF, high pressures generated inside the dialyser compromised membrane permeability and limited the total infusion rate, resulting in an overall reduction in solute removal.

The middle-arm fistula: A new native arteriovenous vascular access for hemodialysis patients.

Dialysis access procedures and complications are important causes of morbidity and hospitalization for chronic hemodialysis patients. The number of complicated subjects on dialysis is increasing, and creating a successful native arteriovenous fistula for these patients is a challenge. The classic Brescia-Cimino fistula may not be the best first choice for a native vascular access. We describe the surgical technique of middle-arm fistula (MAF) for hemodialysis. A total of 112 surgical procedures were performed on 106 patients with primary unassisted 24- and 48-month patency rates of 93% and 83%, respectively, and a very low incidence of complications. Our approach was found to be a useful method in patients with comorbid factors.

Improvement of anemia in hemodialysis patients treated by hemodiafiltration with high-volume on-line-prepared substitution fluid.

BACKGROUND: Hemodiafiltration (HDF) is associated with a lower incidence of neuropathy, carpal tunnel syndrome, joint pain, and partial correction of anemia. HDF with on-line-prepared substitution fluid (OL HDF), as compared with conventional hemodialysis, increases the treatment tolerance and, as compared with standard HDF, avoids storage problems and allows a higher substitution volume at low cost. METHODS: Thirty-two hemodialysis patients treated by OL HDF for at least 9 months were studied. Hemoglobin, hematocrit, iron metabolism, serum albumin, dialysis dose and dry body weight were determined under a settled condition with regular hemodialysis 3 months before the transfer to OL HDF. The same parameters were analyzed 3, 6 and 9 months after the beginning of the new treatment modality. RESULTS: During OL HDF, hemoglobin values significantly increased in patients without addition of recombinant human erythropoietin (rHuEPO): baseline vs. 6 months 11 +/- 1.7 vs. 12 +/- 1.8 g/dl (p < 0.01); baseline vs. 9 months 11 +/- 1.7 vs. 12 +/- 1.6 g/dl (p < 0.05). In patients on a maintenance dose of rhuEPO, this could be significantly reduced, while the target hemoglobin levels were maintained (10.6 +/- 0.9 g/dl): baseline 99.8 +/- 50.4 U/kg/week, 3rd month 76.2 +/- 43 U/kg/week, 6th month 64.3 +/- 37 U/kg/week, and 9th month 59.4 +/- 38.6 U/kg/week (p = 0.007, p = 0.0006, and p = 0.0007, respectively, vs. baseline). Iron metabolism, dialysis dose, dry body weight and serum albumin levels did not significantly change during the follow-up period. Further, a stability of the rHuEPO supplementation was observed in 14 patients followed up for 24 months. CONCLUSIONS: OL HDF influences anemia and rHuEPO dose. It allows considerable anemia correction in patients without rHuEPO treatment, while it significantly reduces rHuEPO doses in those on rHuEPO treatment as compared with standard hemodialysis. The rHuEPO costs are consequently reduced.