Nephronplus poster A0 LR

Wearable artificial kidney
EU/FP7 project Nephron+ 2010-2014 www.nephronplus.eu
L. Lymberopoulos (Exodus, GR), M. Correvon (CSEM, CH), S. Wiegersma (TNO, NL), J. Boomker (Nierstichting, NL), H. Anis (IMST, DE), M.F. Simonis
(Nanodialysis, NL), J. Fils (CEA, F), J. Hartmann (Univ. Krems, AT), M. Wester (UMCU, NL), F. Poppen (Offis, DE)
Nearly 4 million dialysis patients in 2020
Estimates of Fresenius Medical Care suggest an increase to
nearly 4 million dialysis patients in 2020. The average patient
growth is 5-6% per year mainly caused by effects from obese
and overall aging of population. Treatment of dialysis patients in
the western world currently reaches to 85 k€/patient/year
(dialysis treatment plus medical and hospitalization costs). This
would imply an overall health cost expenditure of over 300 billion
€ in 2020.
© Fresenius Medical Care, annual report 2013
Webportal for remote surveillance and personalization of treatment
Intermittent hemodialysis in a central clinic
The majority of End Stage Renal Disease (ESRD) patients are
dependent on hemodialysis treatment in a central clinic three
times a week. Although lifesaving, this treatment is far from ideal.
The blood clearance is relatively poor (20%) and the intermittent
treatment causes significant variations of concentration levels in
the blood. This adversely affects the condition of other organs.
The overall life expectancy is poor: 1 out of 6 patients dies within
one year. Current dialysis machines are bulky in size and require
special equipment for the preparation of dialysate fluid. Dialysis
at home is therefore not very popular. Each hemodialysis
treatment consumes about 120 liters of dialysate. This large
volume of dialysate hampers a mobile, portable or wearable
system.
The Nephron+ dialysis system is remotely monitored by a medical center. Messages and
alarms generated by the operating system and sensor data from the wearable artificial
kidney are being sent and logged to a webportal. Both doctor and patient have access to
the history and actual status of the device and the running treatment. This includes sensor
readings, clearance rate, battery status and operation mode. Patient parameters as blood
pressure and weight are also recorded once a day. Together with feedback from the
patient about his health condition (activity level, sleep, feeling well or sick) a database is
generated that can be analyzed by the doctor. Based hereon the treatment and the
settings of the device can be adapted and fine-tuned to the personal needs of the patient.
Prototype
Prototype versions have become available in 2012 and 2013.
The current prototype that is used for animal trials has a weight
of 3.2 kg. It has a display for manual control but the device can
also be controlled via the smartphone. After the animal trials a
redesign will be performed in view of weight reduction,
ergonomics for wearability and manufacturing ability. A weight
reduction to 2 kg, including battery, is feasible.
Smartphone with Nephron+ app as ICT hub
A smartphone is used to control and to read the device, but it
also serves as ICT hub to the Nephron+ webportal. Messages,
alarms and sensor data are sent via Bluetooth (Continua HDP) to
the smartphone and directed further to the webportal via wifi or
GS3/4. The Nephron+ app allows the patient to read all data
(measurements, wakd status, alarms) from the device and to
change the operation mode if wanted (wakd control). The app
also has a menu for giving feed back about health condition
(questionnaires) and automatic retrieval of weight and blood
pressure (medical devices) via Bluetooth connected devices.
Willem © Nierstichting NL
Slow dialysis while being mobile
For practical and economical reasons dialysis treatment in a
central clinic is limited to a 4 hour session. However a longer
dialysis duration with a slower rate of toxin removal and water
extraction favors the hemodynamic stability and would lower the
mortality (see figure below, RR relative risk of mortality vs
treatment time and Kt/V dialysis dose). Nocturnal home dialysis
with 6-8 hours dialysis sessions reveals improved salt and water
control, increased solute removal and a marked improvement in
quality of life. Slow dialysis is therefore regarded as very
beneficial. Up to now slow dialysis was difficult to realize in
practice. But with the advent of wearable dialysis 24/7 continuous
dialysis has become possible. Wearable dialysis will give patients
freedom to dialyze anywhere, anyplace while being mobile and
allows full participation in social and economical activities.
Wearable system for continuous dialysis using sorbents
A wearable dialysis system enables a slow and continuous 24/7 dialysis treatment
resembling the functioning of healthy kidneys. Hereby variations of concentration levels in
the blood can be kept to a minimum. Thanks to the prolonged duration, the blood
clearance can be improved. Wearability however requires a small and lightweight system.
In Nephron+ a new technology is applied based on sorbents. This eliminates the need of
120 liters of dialysate. The concept is decribed below. The dialysis process is controlled by
an operating system using sensors to ensure safety (pressure, temperature, dialysate
conductivity and pH, air bubble detection, fluid leakage) and efficacy (clearance rate,
potassium and calcium concentration). The system is able to run fully automatic as standa-lone machine. However, the patient has the ability to interfere and to control the device
manually as well. This can be done via an in-built control panel or by a smartphone.
Dedicated sensors
A range of sensors has been developed in order to monitor the
blood clearance and important process parameters. Examples
are the electrochemical platform for K, Ca and pH sensing, a
digital conductivity sensor and a pressure sensor. Not shown are
temperature sensors and a sensor to monitor the vitamin C
concentration.
Longer treatment time and slower ultrafiltration in hemodialysis: Associations with reduced mortality in the
DOPPS, R Saran et al. Kidney International (2006) 69, 1222–1228.
40% cost reduction with wearable
A recent analysis conducted by the Dutch Kidney Foundation in
2012 suggests that the overall costs for in-center hemodialysis
treatment, medication and hospitalization amounts to an average
of 85 k€/patient/year. For a wearable device these costs are
estimated to 50 k€/patient/year. The cost benefits are achieved
by reduction in:
- personnel costs (20 k€)
- overhead (10 k€) and
- transportation costs (5 k€).
Nephron+ concept of dialysis
The dialysis procedure of Nephron+ resembles a normal dialysis operation. Blood is
withdrawn from a patient and is passed through a dialyzer membrane where toxins are
exchanged to a dialysate circuit containing only 150 ml dialysate. This dialysate is
circulated and passed through a sorbent unit for regeneration/refreshing. Compared to
thrice a week in-center hemodialysis (3x4=12 hours dialysis per week) the Nephron+
system can dialyze 150 hours per week, a factor 10 slower. Blood tubings and dialyzer
filter can therefore be downsized to pediatric size which is prerequiste for a wearable
device. To prevent the patient from fluidic overload, excess water is removed in
ultrafiltration mode. Switching to ultrafiltration mode is controlled by the operating system.
A look inside
Action picture from animal trial. The back cover of the device is
opened for sampling purposes. Visible components: dialyzer filter
(pediatric), sorbent unit (black box), pumping units for blood and
dialysate, degas unit, pressure and temperature sensors,
electrochemical platform for pH and K, Ca concentration and a
fluidic switch for switching to ultrafiltration mode.