Measuring intradialyser transmembrane and hydrostatic pressures: pitfalls and relevance in haemodialysis and haemodiafiltration

Ficheux, Alain; Gayrard, Nathalie; Szwarc, Ilan; Duranton, Flore; Vetromile, Fernando; Brunet, Philippe; Servel, Marie-Françoise; Jankowski, Joachim; Argilés, Àngel

doi:10.1093/ckj/sfz033

Cited by 3 publications

(6 citation statements)

References 15 publications

(22 reference statements)

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“…Impact of filtration fraction ( FF ) on transmembrane pressure ( TMP ) in postdilution hemodiafiltration (HDF) 36 . Measured data correspond to the average of eight measurements made in vivo with initial Hct 0.357, total plasma protein 62.5 g/L, Q b 350 ml/min.…”

Section: Boundary Layersmentioning

confidence: 99%

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Basic physics of hemodiafiltration

Pstras

Ronco

Tattersall

2022

Seminars in Dialysis

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Standard high-flux hemodialysis (HD) clears urea very efficiently but is less efficient at clearing uremic toxins with larger molecule size, which diffuse more slowly. Hemodiafiltration (HDF) provides much higher convection rates, thereby reliably increasing the clearance of these larger toxins. However, the high ultrafiltration volumes employed by HDF significantly increase the concentration of proteins and lipids in the dialyzer blood compartment. This has the effect of increasing plasma viscosity, which opposes solute diffusion, and increasing plasma oncotic pressure, which opposes convection. The negatively charged plasma proteins also influence the equilibration of ions between dialysate and blood compartments. These effects result in varying conditions for solute transport along the length of the dialyzer and along the radial distance from the membrane within the dialyzer fibers. High-flux dialyzers can be designed to augment solute diffusion and internal filtration, so that their performance approaches that of HDF. This avoids some of the mechanical complexity of HDF, but such enhanced dialyzers may be more difficult to manufacture, control and monitor. Here, we present and discuss the most important physical phenomena associated with HDF therapy, providing an overview of its main concepts and principles.In particular, we discuss the physics of solute diffusion and convection and the factors affecting them, and we compare predilution or postdilution HDF with enhanced HD.

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Section: Boundary Layersmentioning

confidence: 99%

“…The actual ratio Q uf / TMP during treatments will be variable due to the nonlinear changes in viscosity and oncotic pressure with FF 36 . (Figure 4).…”

Section: Ultrafiltrationmentioning

confidence: 99%

Basic physics of hemodiafiltration

Pstras

Ronco

Tattersall

2022

Seminars in Dialysis

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“…Both modalities are attractive options since they promote higher clearance of middle molecules such as myoglobin than hemodialysis (CVVHD) with a high-flux membrane. 62,63 The drawback of convective modalities is related to elevated filtration fraction 64 and elevated transmembrane pressure 65 that are inherent to these strategies of blood purification and are associated with a reduction in filter life span. 62,66 The HCO membrane is utilized only for CVVHD 67,68 and to date, no sets with MCO filters for CRRT are commercially available.…”

Section: Med I Um and Hi G H Cut-off Memb R Ane Smentioning

confidence: 99%

Continuous renal replacement therapy and extended indications

Ronco

Reis

2021

Seminars in Dialysis

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Initially developed to replace kidney function in severely ill newborns/infants, and then diverted to severely ill adult patients, 1 continuous renal replacement therapy (CRRT) is now applied to support different organs apart from the kidney in a myriad of clinical conditions such as sepsis, 2 acute liver failure (ALF), 3 acute respiratory distress syndrome (ARDS), 4-6 and cardiogenic shock. 7 The extended indications for CRRT and the concept of sequential extracorporeal therapies 8 are intrinsically related. The individualization of care and selection of treatment candidates based on clinical and molecular phenotypes increases the probability of benefit for each of the proposed blood purification techniques 9-15 (Figure 1).In sepsis, the removal of damage-associated molecular patterns (e.g. cytokines) and pathogen-associated molecular patterns (e.g. endotoxins) might reduce the burden of the disease. 16 In liver failure, CRRT reduces the risk of ammonia-related neurotoxicity while artificial liver support systems effectively reduce bilirubin and bile acids concentrations. 3 In ARDS, extracorporeal CO 2 removal (ECCO 2 R) allows the application of ultra-protective ventilation avoiding deleterious consequences of hypercapnia and reducing the risk of ventilator-associated lung injury. [17][18][19] In cardiogenic shock and cardiac surgery in which shifts in fluid balance are poorly tolerated, CRRT might mitigate further myocardial damage. 20,21

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“…For example, if the ultrafiltrate volume is 21 L and the reinfusion volume 19 L, at the end of the session the patient will have a reduction of 2 kg (~2 L) in his body mass. An inherent consequence of high convective volumes is the increment in the transmembrane pressure 14 , associated with higher deposition of proteins in the inner surface of the hollow fibers, partial obstruction of pores, and loss of membrane efficiency during the treatment, a phenomenon termed as clogging 15 . In this update article we discuss the innovations in the field of HD membranes; Table 1 shows a list of core concepts and their definitions regarding HD membranes.…”

Section: Introductionmentioning

confidence: 99%

“…Both modalities are attractive options since they promote higher clearance of middle molecules such as myoglobin (17 kDa) than CVVHD with an HF membrane. The drawback of convective modalities is related to elevated filtration fraction and elevated transmembrane pressure 14 that are inherent to these procedures, being associated with a reduction in filter life span 25 . Weidhase et al 26 .…”

Section: Introductionmentioning

confidence: 99%

Disruptive technologies for hemodialysis: medium and high cutoff membranes. Is the future now?

et al. 2021

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In the past decade, a new class of hemodialysis (HD) membranes (high retention onset class) became available for clinical use. The high cutoff (HCO) and the medium cutoff (MCO) membranes have wider pores and more uniformity in pore size, allowing an increased clearance of uremic toxins. Owing to the mechanism of backfiltration/internal filtration, middle molecules are dragged by the convective forces, and no substitution solution is needed. The HCO dialyzer is applied in septic patients with acute kidney injury requiring continuous kidney replacement therapy. The immune response is modulated thanks to the removal of inflammatory mediators. Another current application for the HCO dialyzer is in hematology, for patients on HD secondary to myeloma-kidney, since free light chains are more efficiently removed with the HCO membrane, reducing their deleterious effect on the renal tubules. In its turn, the MCO dialyzer is used for maintenance HD patients. A myriad of clinical trials published in the last three years consistently demonstrates the ability of this membrane to remove uremic toxins more efficiently than the high-flux membrane, an evolutionary disruption in the HD standard of care. Safety concerns regarding albumin loss as well as blood contamination from pyrogens in the dialysate have been overcome. In this update article, we explore the rise of new dialysis membranes in the light of the scientific evidence that supports their use in clinical practice.

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Measuring intradialyser transmembrane and hydrostatic pressures: pitfalls and relevance in haemodialysis and haemodiafiltration

Cited by 3 publications

References 15 publications

Basic physics of hemodiafiltration

Basic physics of hemodiafiltration

Continuous renal replacement therapy and extended indications

Disruptive technologies for hemodialysis: medium and high cutoff membranes. Is the future now?

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