When It Happens Panel Get involved: send your photos, videos, news & views by texting 'OXFORD NEWS' to 80360 or email
Glysure monitor could save lives
A patient recovering from surgery or trauma in an intensive care unit (ICU) needs essentially three nutrients to survive and to sustain the body while it heals — oxygen, water and sugar.
But an excess of any one can cause collateral damage. A premature baby given too much oxygen can develop retinopathy and go blind; excess water will overload the system and the fluid will come out through the lungs.
A surfeit of blood sugar or glucose can also produce adverse results.
Dr Greet van den Berghe’s landmark paper in the New England Journal of Medicine in 2001 showed that compensating for temporary insulin resistance yields significant improvements in outcomes for critically ill patients.
Mortality reduces by 34 per cent, sepsis by 46 per cent, renal failure by 41 per cent and blood transfusions by 50 per cent. The therapy is called Tight Glycaemic Control or TGC.
That glucose increases after surgery or trauma had been known by clinicians for some time and accepted as part of the body’s natural processes. But not until Dr van den Berghe’s study was either the significance or the potential danger understood.
To control high sugar levels demands insulin, in exactly the same way a diabetic maintains glucose readings.
Insulin is one of the most dangerous drugs, as highlighted recently in the contamination of saline drips in a UK hospital.
In the United States, 18 per cent of medication errors concern insulin.
Insulin, unlike most drugs, is not a weight-related dose and insulin resistance in a patient will change.
Accurate insulin therapy for ICU patients demands constant and accurate monitoring, a regime of probably hourly intervals.
Traditional finger prick blood sampling presents several problems. The patient will rapidly develop sore fingers and hands. In an ICU of ten patients, with each sample taking around five minutes, sampling will take a whole hour, then the cycle begins again.
As a result, sampling will occupy a nurse full time, a significant cost. In an era of escalating healthcare expenditure, cost effectiveness is a box that has to be ticked for a treatment to be adopted.
Glysure, based in Abingdon Business Park, has developed a continuous blood glucose monitoring system.
Chief executive Chris Jones explained: “The heart of the monitoring lies in the sensor, which is inserted through a central venous catheter or arterial line.
“Either one of these will already be in use on an ICU patient for other sampling or intravenous drugs, so our device piggy-backs. The design of our sensor allows it to remain in the body throughout a patient’s stay in ICU.”
The sensor, no thicker than a hypodermic needle, is attached to a fibre-optic cable which connects to the monitor.
It looks deceptively simple, but took the first two years of Glysure’s research to develop to a point where it reached proof of concept.
To ensure it is not seen as a foreign object by the body, the sensor is coated to be bio-compatible.
A membrane blocks all but tiny molecules and a gel acts as a filter. Within the membrane lies a clever piece of chemistry that binds temporarily with glucose molecules.
The more the glucose, the greater the fluorescence and vice-versa. A light pulse down the fibre optic twice per minute feeds the fluorescence measurement back to the monitor.
Key to the system is that the chemistry is not consumptive, it does not use up its chemicals. It is known as a reversible equilibrium reaction.
A one-time calibration cassette that links directly to the monitor is used to check the accuracy of the readings, backed up by a small number of actual blood samples that are laboratory tested.
In 2010, Glysure conducted pilot clinical trials on some 90 patients, testing on 20, incorporating the lessons learned, then taking the improved model to the next 20 and so on.
The company has just secured third round funding of £7m, which it will use to conduct full clinical trials on 50-100 patients.
The trials will be aimed at securing European CE marking and US Food and Drug Administration approval for a medical device.
The firm’s Abingdon base is undergoing expansion to offer greater manufacturing capability and will come on stream in March.
Once quality systems are proven, the CE marking and FDA trials will begin in summer. The first systems are scheduled to be on the market in early 2013.
Each sensor will cost a remarkably low £110 and offer savings per patient of around £1,000 from early release from ICU and a reduction in renal failure.
The firm has grown from ten staff in 2006 to 17 — and another five to eight people will be recruited this year.
“The clinicians cannot wait to get their hands on our system,” Mr Jones said. “Ultimately, they want an integrated product that both monitors the glucose and dispenses the insulin, but that is some way down the line.”