The control of blood glucose levels is one of the most important factors
for patients in intensive care units (ICU). Thousands die or suffer
prolonged illness every year, simply because intensive care units are
unable to monitor their patients' glucose levels during recovery. One EU
project CLINICIP is developing an intelligent, automated glucose
monitoring and control system to solve the problem.
reason for the large number of deaths is the fact that glucose affects
blood toxicology, so careful management is essential to keep patients in
the best possible health. Many ICUs cannot easily control the glucose
levels in each patient's blood.
Healthcare staff rely on a technique called 'tight glucose control',
also known as 'intensive insulin therapy', which uses insulin to control
the glycaemic state of recovering surgical patients. The same method is
also used to help patients at medical intensive care units to recover
"Studies show that when patient's glucose levels are managed
carefully, the mortality is reduced and the morbidity is reduced too,"
says Martin Ellmerer, scientific director of the
CLINICIP project. "This is not
just about diabetic patients, though it is important for them too.
Glucose management is important, we know for sure, for medical and
surgical intensive care patients. It's also important in paediatric
intensive care cases. Intensive insulin therapy helps many different
kinds of patient to survive or achieve a better recovery."
It is five years since medical science realised how vital glucose
control is to ICU outcomes, but there is still no complete solution to
glucose management, because it is a very, very difficult problem.
"Taking glucose levels manually is time-consuming, and even when you
have accurate, regular data, the impact of glucose levels varies from
patient to patient, as does the dose of insulin required. It's a very
complex problem, one that seems to be even more complex in critical
illnesses than in diabetes management," said Ellmerer.
Automated insulin delivery
The EU-funded project CLINICIP, the Closed Loop Insulin Infusion for
Critically Ill Patients hopes to develop an intelligent, automated
glucose monitoring and control system for ICUs. It's called
'closed-loop' because monitoring glucose levels and administering
insulin would be completed by one self-contained system.
A closed-loop system needs inputs, analysis and outputs. The CLINICIP
partners are developing a system that links glucose measurement to a
control unit that assesses a patient's needs, and then releases insulin
into a saline drip automatically.
They have already developed an algorithm to analyse how much insulin
is needed, based on carbohydrate intake and current glucose levels. The
team believe they have solved the problem, but it will require long-term
validation to get the correct fine-tuning. That algorithm is in trials,
and the partners hope to have initial results early next year.
"We are now testing the algorithm, which could be commercialised as a
diagnostic support tool," says Ellmerer.
Internal or external glucose sensors?
project is also currently studying sensor systems, both intra-vascular
and extra-vascular — that is, within and outside the veins. If
successful, automated sensor systems could greatly improve the survival
chances of intensive care patients. They could also increase efficiency
in clinical practice. That, however, is a long-term goal.
On the glucose sensor system, Ellmerer notes that, "Ideally we would
like to use a sensor outside of the blood vessels. It's less invasive,
and evidence suggests that it can provide a very accurate indication of
real glucose levels in the blood."
But first the team must establish that the external sensor is
accurate and reliable. The intravascular system is both accurate and
reliable, but it is more invasive and time consuming, and not really
appropriate for some types of patient such as cardiac arrest victims and
The body interface obstacle
The major obstacle currently facing the project is the body
interface, or how the sensor in the body links to the rest of the
closed-loop system. Ellmerer says that the team would be interested in
hearing from any industrial partners involved in this area.
Even if the body interface problem is solved soon, he believes the
full closed-loop system will not be developed within the lifetime of the
project, which ends in January 2008. The work will continue however.
"There are bilateral agreements between many of the partners to continue
the work that we've started here after the life of the project," said
In the meantime, CLINICIP's algorithm has provoked intense interest
among medical scientists, and there have been calls to make the
algorithm available to all ICUs.
"But it's just not possible yet. We haven't established definitively
that it is sufficiently accurate, reliable and safe," warns Ellmerer.
"That assessment is under way now."