Device could detect overdose drugs

A prototype of the device

Scientists are developing a hi-tech device which could help casualty doctors treat patients who have taken an overdose.

The biosensor would detect what drugs they had taken much faster than the lab tests currently used, helping doctors give a patient the treatment they need more quickly.

The device acts by testing patients' blood.

Early tests have shown it can detect glucose, and researchers are also looking at whether it could detect creatinine, a product in the body, which is an indicator of kidney dysfunction.

It would be useful to know immediately what the patient has taken

Dr Fiona Lecky, A&E consultant

It is hoped biosensors can be developed which would detect paracetamol, antidepressants and even illegal drugs.

Its developers say it would take just a few minutes to give a result, whereas sending a sample off to a laboratory may take hours to come back with a result.

The device, which could cost hospitals around £1,000 is at a very early stage of development and it could be three to five years before it would be in use.

Reaction chamber

The biosensor has a disc-shaped quartz crystal, around a centimetre in diameter and 0.2 millimetres thick at its centre.

When it is charged with electricity it vibrates millions of times a second, and the frequency at which it vibrates changes if anything sticks to the crystal's surface.

Above the crystal is a small reaction chamber where blood samples are placed.

The biosensor can be designed so that a particular series of chemical reactions will take place if a certain substance is present, forming a solid product.

That will then attach itself to the crystal and change the vibration frequency showing that the substance is present.

Its makers claim the chemical reaction can be made to be highly specific so that other substances will not interfere with the readings.

Faster treatment

Dr Sub Reddy, a lecturer in biosensors at the University of Surrey, UK, led the research, which is backed by the Engineering and Physical Sciences Research Council.

He said: "Our sensor is portable and will be easy to use even by unskilled staff."

Dr Reddy told BBC News Online: "You could have a bank of these devices in the ambulance, so you could have the results on a whole series of drugs that the patient could have taken as soon as they arrived in A&E.

"That would improve the speed of treatment, and mean doctors could give any antidote."

Dr Fiona Lecky, an A&E consultant at Hope Hospital, Salford, said: "We do have to wait for the results of blood tests.

"Also the blood tests are very limited in what they will pick up - aspirin and paracetamol.

"It would be useful to know immediately what the patient has taken, particularly in an unconscious patient.

"The main issue with this device would be is it reliable, and its cost."