Glucose monitor could prevent complications in ICU patients

Venture-capital-backed Glysure, based in Oxford, uses sensor technology based on fibre optics and reversible fluorescent chemistry in a fully automated catheter system.

‘There’s been research showing, whether you’re diabetic or not, patients come out of big surgeries, such as cardiac surgeries or trauma, and end up with elevated glucose,’ Chris Jones, Glysure chief executive officer, told The Engineer.

This puts them at risk of sepsis, renal failure, the need to have blood transfusions and death. Indeed, glucose shows a so-called ‘U-shaped mortality curve’, meaning that there is an extremely narrow target range and a severe penalty for falling outside of it.

This makes accurate, minute-by-minute glucose monitoring potentially life saving for certain patients. However, this task currently has to be done manually by nurses, which is mostly out of the question for overburdened hospitals.

Glysure set about looking at various sensor technologies that could be adapted to the real-time monitoring of glucose.

‘The technical term for it is photo-induced electron transfer or PET,’ Jones said of the proprietary technology.

He explained that the PET sensor has a gel pocket containing boronic acid glucose receptors attached to a fluorophore. In the unbound state, the fluorophore is quenched; but when glucose binds, the level of fluorescence increases in proportion to the concentration, which is then quantified by the fibre optics.

‘You’re measuring whole blood directly at the source, so you can avoid a lot of the lag you get if you try to measure interstitially [in fluid spaces] and you avoid some of the problems you have with fingersticks where you’re getting mixed samples and contaminated samples,’ Jones said.

Intended for a single use, the sensor is shipped in a sealed pod that can be calibrated in a monitor with a known level of glucose, then fully opened and placed into a patient’s catheter. Jones said this ensures ‘touch-free’ introduction to maintain device sterility.

In recent clinical trials of Glysure’s device, critically ill patients were monitored continuously and accurately for blood glucose levels throughout their length of stay in the intensive care unit (ICU) for up to 100 hours before discharge.

Full regulatory trails in Europe and the US will commence next year to obtain CE and FDA approval respectively, so the company can start to market the monitor and sensor packages to hospitals.

‘There’s an argument that if you reduce morbidity, get people out of the ICU faster, you reduce infection and all of that will reduce the cost of care to the hospital, so the patient wins and the hospital wins,’ said Jones.