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Dialysis
Fast Transport Status in Peritoneal Dialysis Patients –
Greater Knowledge, Better Treatment
a report by
Anabela Rodrigues
Nephrology Consultant and Associate Professor of Nephrology, University of Porto
Peritoneal transport evaluation is a key issue in the management of mesothelial cells into myofibroblasts, or epithelial-to-mesenchymal
peritoneal dialysis (PD) patients, in whom it is important to ensure transition. Fibrotic tissue may support and preserve angiogenesis.
8
It
adequate small-solute transport and fluid removal.
1
A fast peritoneal seems that mesothelial cells that have undergone epithelial-to-
transport rate as expressed by dialysate/plasma ration of creatinine (D/P mesenchymal transition produce more VEGF than epithelioid mesothelial
creatinine) levels higher than 0.81 or by D/P creatinine higher than the cells,
9
suggesting links among mesothelial cell transdifferentiation,
average (plus standard deviation) levels of the studied population
2
would fibrosis and acquired fast transport. This status is also a risk factor and an
be expected to allow higher dialysis clearances. However, more rapid early marker of encapsulating peritoneal sclerosis, a rare although serious
dissipation of the osmotic gradient due to glucose absorption causes and life-threatening PD complication.
10
The use of low-guanosine
reduction of ultrafiltration capacity and less fluid removal. This leads to 5-diphosphate (GDP) two-chambered solutions is expected to reduce
high risk of the metabolic consequences of glucose absorption and these effects.
hypervolaemia. This makes a fast transport rate an immediate problem to
be managed in day-to-day clinical practice.
3
Less is known about the determinants of intrinsic baseline peritoneal
fast transport status. The effective capillary surface depends not only
What Have We Learned? on the number of anatomic capillaries, but also on the vessels – which
PD has already progressed through important stages.
4
In recent years, are perfused and in some instances recruited or dilated – variably
basic research with cell cultures and animal models has allowed increased distributed in the interstitium. It has been hypothesised, though not
knowledge of the molecular pathways of structural and functional yet confirmed, that systemic inflammation
11
such as uraemia or
alterations in membrane under chronic exposition to PD. These diabetes mellitus
12,13
could induce increased effective capillary surface
longitudinally acquired changes of peritoneal function in PD patients are at the start of PD. Others, however, refute such associations.
14–18
mainly expressed as an increase in low-molecular-weight-solute transport Furthermore, analysing predictors of baseline fast transport in relevant
and ultrafiltration capacity failure.
5
studies
14,19
has allowed us to conclude that epidemiological variables
account for very little of the variability in solute transport between
There is evidence of accumulation of advanced glycation end-products patients commencing PD.
20
(AGEs) in the peritoneal membrane in uraemia, exposure to high glucose
concentrations and exposure to glucose degradation products.
6
Technical failure, co-morbidity and higher mortality have previously been
Interaction of AGEs and receptors for advanced glycation end-products associated with fast transport status.
21–23
While the ADEquacy of
(RAGEs) leads to secretion of inflammatory cytokines and growth factors. Peroteneal Dialysis in Mexico (ADEMEX) and other studies have refuted
These include vascular endothelial growth factor (VEGF), an important this association, a recent meta-analysis,
24
including 20 observational
mediator of neoangiogenesis with mesothelial cells being its important studies, demonstrated a mortality-relative risk of 1.15 for every 0.1
source, and transforming growth factor (TGF)-β, which plays a central increase in the D/P creatinine. However, incident and prevalent fast
role in submesothelial fibrogenesis.
7
TGF-β mediates conversion of transporters must be evaluated separately because they represent
heterogeneous populations. It would be controversial if intrinsic baseline
fast transport status brought uniformly similar threats.
15,25,26
Besides,
Anabela Rodrigues is a Nephrology Consultant and
Associate Professor of Nephrology at the University of Porto,
clinical results might depend more on the strategies of fluid
Instituto Ciencias Biomédicas Abel Salazar. She works in the management
27
not usually detailed in publications. In the absence of
fields of clinical nephrology, dialysis and transplantation and
sufficient residual renal function, this status usually implies
has been Physician-in-Charge of the Peritoneal Dialysis Unit
in the Department of Nephrology at Hospital Geral Santo
individualisation of prescription with shorter dwell times (automated
Antonio in Porto since 1998. The unit has increased its
peritoneal dialysis), increased use of hypertonic glucose solutions or,
activity steadily and treats around 100 patients per year. She
preferably, an alternative agent with colloid-osmotic properties, such as
is responsible for post-graduate doctor training in the field
of peritoneal dialysis and is a Member of the Portuguese icodextrin, as has been electively recommended.
27–29
Therefore, timely
Nephrology Society Scientific Committee. She served as a
detection, characterisation and adequate therapeutic strategies are
member of the Committee for Peritoneal Dialysis European
Best Practice Guidelines and is a Council Member for the
fundamentally important for the outcome of these patients.
International Society of Peritoneal Dialysis. She completed a
PhD in the field of peritoneal transport, with Professor
Assessment of Peritoneal Membrane in Clinical Practice
Doctor Raymond T Krediet as promoter.
Clinicians have focused on small-solute peritoneal transport evaluation.
E: ar.cbs@mail.telepac.pt
The ability of the membrane to transport a given solute is governed by
the permeability of the membrane to that solute and its effective surface
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