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In a small critical care unit with only 10 patients, this
means 20 minutes per hour; 8 hours a day. Typically,
nurses work in shifts of six hours. Therefore, each day
one and a third nurses’ shift are required only for tasks
related to monitoring urine output. Even a partial au-
tomation of these tasks has the potential of yielding
significant economic savings.
5 CONCLUSIONS AND FUTURE
WORK
We have built a device capable of automatically sens-
ing and supervising the urine output of critical care
patients. The device comprises two containers of dif-
ferent volumes, a small one that receives the urine
coming from the patient’s bladder, and a greater vol-
ume container in which the first container releases
its content when it gets full. Both containers release
their content automatically when they are filled using
a siphon mechanism.
The containers are equipped with reed switches
that are activated by a magnet that is attached to a float
located inside the containers. These reed switches al-
low us to identify the instants at which they get filled
with urine. An electronic unit sends via Bluethooth
the information provided by the reed switches to a PC
which calculates the urine output from the switches’
state, and supervises the achievement of the thera-
peutic goals established by the clinician. The error
in measuring the patient’s urine output is under 2%.
The large container is the one which allows us to ob-
tain this high accuracy, while the small one permits
an early warning of deviations from the therapeutic
goals.
The cost of our device is slightly higher than the
cost of the commercial devices currently used in mon-
itoring urine output. However, the device has the po-
tential to save costs for the institutions that provide
health services by freeing a considerable amount of
time for the healthcare staff. Furthermore, it pro-
vides a more continuous supervision of the urine out-
put than is currently carried out in critical care units,
which may help improve patient outcomes.
As future work, we intend to take advantage of
all the state changes of the reed switches of the large
container to correct the urine output measures while
the large container is been filled. Currently, this cor-
rection is only performed when the large container re-
leases the urine. We also will start to use our device
in animal tests conducted in a research unit associated
with Getafe University Hospital. After this phase, we
intend to use it in a pilot test in the Intensive Care Unit
of this hospital.
ACKNOWLEDGEMENTS
We would like to acknowledge the support by the
Ministry of Science and Innovation of Spain, the Eu-
ropean Regional Development Fund of the European
Commission under the grant TIN2009-14372-C03-
03. T. Akinfiev acknowledges the financial support
received from CSIC under the project “New actua-
tors with high efficiency and control algorithms for
automation and robotics”. A. Apalkov acknowledges
the financial support from Ministry of Science and In-
novation of Spain under Juan de la Cierva Program.
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