López-Herce, Jesús

Santiago, Maria Jose

Sánchez, Amelia

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The Authors Reply 

clinical efﬁcacy of this system.3,4 In the last 3 years, we treated
15 patients with ECMO and CRRT. In contrast to the setup
suggested by the authors, we connected the ﬁlter inlet
of the CRRT machine after the ECMO pump, and the ﬁlter
outlet was then returned to the ECMO circuit before the
pump (into the reservoir, if present): The CRRT circuit,
running counter-current to extracorporeal assistance, allows
the blood to be infused into the venous ECMO section
(where the patient is drained) and then to be aspired from the
arterial ECMO section (where blood returns to the patient)
(Figure 1). In our opinion, there are several reasons to prefer
this setup. First, ECMO connection lines are generally used
for circuit pressure monitorization, and frequently one
connection in the ECMO venous line and one in the arterial
line remain available. Second, this might reduce blood ﬂow
resistance and turbulence after the centrifugal pump and
improve reservoir drainage when a roller pump is present.
Blood recirculation induced by this circuit setup is negligible,
considering that the CRRT to ECMO blood ﬂow ratio is
never 40.1. The only requirement to take into consideration
during roller extracorporeal assistance is to increase ECMO
blood ﬂow by the same amount as CRRT blood ﬂow, to
compensate the shunted circulation. Interestingly, during
centrifugal ECMO, the ﬂow is self-adjusted to the increased
value, considering the additional pre-pump blood ﬂow coming
from the CRRT circuit and reduced resistances after the
centrifuge due to blood aspiration into the dialysis machine.
1. Santiago MJ, Sa´nchez A, Lo´pez-Herce J et al. The use of continuous renal
replacement therapy in series with extracorporeal membrane oxygenation.
Kidney Int 2009; 76: 1289–1292.
2. Ricci Z, Polito A, Giorni C et al. Continuous hemofiltration dose calculation
in a newborn patient with congenital heart disease and preoperative renal
failure. Int J Artif Organs 2007; 30: 258–261.
3. Ricci Z, Morelli S, Vitale V et al. Management of fluid balance in continuous
renal replacement therapy: technical evaluation in the pediatric setting.
Int J Artif Organs 2007; 30: 896–901.
4. Ricci Z, Carotti A, Parisi F et al. Extracorporeal membrane oxygenation and
high-dose continuous veno-venous hemodiafiltration in a young child as a
successful bridge to heart transplant for management of combined heart
and kidney failure: a case report. Blood Purif 2009; 29: 23–26.
Zaccaria Ricci1, Claudio Ronco2 and
Sergio Picardo1
1Department of Pediatric Cardiosurgery, Bambino Gesu` Hospital, Rome, Italy
and 2Department of Nephrology Dialysis and Transplantation, St Bortolo
Hospital, Vicenza, Italy
Correspondence: Zaccaria Ricci, Department of Pediatric Cardiology and
Cardiac Surgery, Bambino Gesu` Hospital, Piazza S. Onofrio 4, Rome 00165,
Italy. E-mail: zaccaria.ricci@fastwebnet.it
Kidney International (2010) 77, 469–470; doi:10.1038/ki.2009.495
The Authors Reply: After having read Dr Ricci et al.’s1
comments about our article,2 we would like to add some
considerations.
The papers published by these authors are single-case
descriptions that basically refer to the working of the
continuous renal replacement therapy (CRRT). In these
papers no assessment of CRRT and extracorporeal membrane
oxygenation (ECMO) working in-line was carried out.3,4 On
the contrary, our study evaluates these characteristics in vitro,
in an animal model as well as in children, through a clinical
prospective study.2
Similar to our model, Ricci et al. connect the ﬁlter inlet of
the CRRT machine after the ECMO pump, but the ﬁlter
outlet is returned to the ECMO circuit before the pump (into
the reservoir, if present). The authors suggest that this type of
connection may have some advantages:
(1) One connection in the ECMO venous line and one in the
arterial line are available. However, this depends on the
type of ECMO circuit used. In our type of circuit, the
CRRT device is connected through a three-way luer lock
connection that allows measurement of the pressure and
the infusion of heparin simultaneously in the same line.
This also makes the connection and withdrawal of the
circuit easy at any time without causing any alteration in
the ECMO function.
(2) This might also reduce blood flow resistance and
turbulence after the centrifugal pump and improve
reservoir drainage when a roller pump is present. We are
not aware of any study having measured the turbulence
and resistance to blood flow or suction pressures in the
reservoir after the connection of the CRRT to the ECMO
circuit, but the effect is likely to be minimum because, as
the authors say, the CRRT to ECMO blood flow ratio is
never greater than 0.1.
So, what disadvantages might the connection that Dr Ricci
et al. propose have? As the ECMO pump exerts a negative
pressure in the reservoir and/or the circuit, which could be
transmitted to the CRRT device and could cause errors in the
outlet pressure, as well as decrease in the ﬁlter pressure and
transmembrane pressure, important information regarding
the state of the ﬁlter could be lost.
In conclusion, connecting the CRRT device to the ECMO
circuit improves the handling of the CRRT device.
Probably there is no unique method to connect these
devices, and each institution must assess and decide on
which method to adopt depending on the circuit and machine
they use.
1. Ricci Z, Ronco C, Picardo S. CRRT in series with extracorporeal
membrane oxygenation in pediatric patients. Kid Int 2010; 77:
469–470.
2. Santiago MJ, Sa´nchez A, Lo´pez-Herce J et al. The use of continuous renal
replacement therapy in series with extracorporeal membrane oxygenation.
Kidney Int 2009; 76: 1289–1292.
3. Ricci Z, Polito A, Giorni C et al. Continuous hemofiltration dose calculation
in a newborn patient with congenital heart disease and preoperative renal
failure. Int J Artif Organs 2007; 30: 258–261.
4. Ricci Z, Morelli S, Vitale V et al. Management of fluid balance in continuous
renal replacement therapy: technical evaluation in the pediatric setting. Int
J Artif Organs 2007; 30: 896–901.
Maria Jose Santiago1, Amelia Sa´nchez1 and
Jesu´s Lo´pez-Herce1
1Pediatric Intensive Care Department, Hospital General Universitario
Gregorio Maran˜o´n, Madrid, Spain
470 Kidney International (2010) 77, 468–472
l e t te r to the ed i to r
Correspondence: Jesu´s Lo´pez-Herce, Pediatric Intensive Care Department,
Hospital General Universitario Gregorio Maran˜o´n, Dr Castelo 47, Madrid
28009, Spain. E-mail: pielvi@ya.com
Kidney International (2010) 77, 470–471; doi:10.1038/ki.2009.497
Nephroprotective drugs from
traditionally used Aboriginal
medicinal plants
To the Editor: The recent article by Farese et al.1 sheds light
on a very important source area of drug development,
medicinal plants. People in different cultures, all over the
world, have used medicinal plants for a number of diseases.
One such traditional medicine system is that of the Canadian
Aboriginals. This system has been practiced for centuries and
encompasses treating the whole person through mind, body,
and spirit. Medicinal plants make up the most important tool
in curing a disease. Table 1 lists selected plants used by
Aboriginal tribes all over Canada for kidney diseases. Mostly,
these are used for diuresis, renal stones and cleansing the
kidneys. Plants have also been a major source of new drugs
since the inception of modern pharmacology.2 According to a
survey, one-third of all the newly approved compounds are
derived from plants.2 A brief review of the literature shows
different plants being effective in preventing/treating renal
diseases either in animal models or in clinical trials.3,4 Some
renal conditions reported to respond to plant therapy are
glomerulonephritis, IgA nephropathy, membranous nephro-
pathy, glomerulosclerosis, immune complex nephritis, ne-
phrotic syndrome, lupus, tubulointerstitial nephritis, chronic
allograft nephropathy, kidney stones, etc.3,4 Some pharmaco-
logical characteristics seen in plants that may contribute in
the above-mentioned conditions are antiinﬂammation; anti-
oxidation; diuresis; immunomodulation; prevention of acute
allograft rejection and drug-induced nephrotoxicity; reduc-
tion in proteinuria, renal interstitial ﬁbrosis, renal ischemia/
reperfusion injury, tubular and mesangial cell proliferation,
blood lipid levels, blood pressure, lipid peroxidation,
apoptosis, renal necrosis, and calcium oxalate crystal
aggregation; and stimulation of renal repair mechanisms,
RNA and protein synthesis.3,4 Continued efforts are required
to identify and develop traditionally used medicinal plants
in renal diseases so that more effective treatments are
available from plants that have been known for their efﬁcacy
for hundreds of years.
1. Farese S, Kruse A, Pasch A et al. Glycyrrhetinic acid food supplementation
lowers serum potassium concentration in chronic hemodialysis patients.
Kidney Int 2009; 76: 877–884.
2. Ghayur MN. Role of medicinal plants and their constituents in the
understanding and evolution of pharmacology and the autonomic
nervous system. In: Govil JN, Singh VK (eds). Recent Progress in Medicinal
Table 1 | List of selected Aboriginal medicinal plants traditionally used in kidney diseases
Scientific name
Common name
(plant type) Family Part used
Traditional use
(preparation) Habitat (tribe)
Acer
pensylvanicum
Striped maple (tree) Aceraceae Bark Diuretic (bark tea) NB, NS, PE, QC, ON
(Penobscot, Micmac)
Arctostaphylos
uva-ursi
Bearberry (shrub) Ericaceae Leaf Diuretic (tea of leaves) All of Canada (Algonquin,
Blackfoot, Micmac, Salish)
Cornus
canadensis
Bunchberry (herb) Cornaceae Whole plant Kidney problems (drinking
steeped plant)
All of Canada (Micmac)
Cucurbita sp. Squash (vine) Cucurbitaceae Seed Diuretic (chewing seeds,
seeds pulverized and taken
with water)
ON, QC (Chippewa, Plains
Indians)
Juniperus
cummunis
Juniper (tree) Cupressaceae Twig, berry Kidney problems (twig and
berry tea)
All of Canada (Gitxsan,
Blackfoot, Micmac, Cree)
Epigaea repens Trailing arbutus (shrub) Ericaceaae Leaf Kidney stones (infusion of
leaves)
Southern Canada
(Algonquin, Iroquois)
Larix laricina Tamarack (tree) Pinaceae Gum Kidney problems (chewing
of gum)
BC, ON, QC, Atlantic Canada
(Cree, Ojibwe, Chippewa)
Ledum
groenlandicum
Labrador tea (Shrub) Ericaceae Leaf Kidney problems (leaves
infusion)
All of Canada (Cree, Micmac)
Medeola
virginiana
Cucumber root (herb) Liliaceae Crushed dried
berry and leaf,
root
Diuretic (berry and leaf
infusion; chewing root)
NS, NB, QC (Iroquois)
Pinus strobus White pine (tree) Pinaceae Bark, needle,
twig
Kidney and urinary
problems (tea of plant parts)
Atlantic Canada, QC, ON, MB
(Algonquin, Iroquois,
Ojibwe, Micmac)
Sarracenia
purpurea
Purple pitcher plant
(herb)
Sarraceniaceae Root Kidney problems (drinking
steeped root)
Southern Canada (Micmac)
Abbreviations: BC, British Columbia; MB, Manitoba; NB, New Brunswick; NS, Nova Scotia; ON, Ontario; PE, Prince Edward Island; QC, Quebec.
Kidney International (2010) 77, 468–472 471
l e t t e r to the ed i to r


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