Tapping a rich vein

A team of researchers from the 

has developed a cheap, handheld device that uses Doppler ultrasound to detect veins quickly for administering injections.

Certain physical conditions such as dehydration, bruises, burns and cardiac complaints can make it difficult for medics to locate a vein. The device will make the process of giving an injection faster and more accurate, especially in time critical emergency situations.

The Doppler effect is an apparent change in the frequency of an electromagnetic or sound wave when the source and observer move in relation to each other. The device transmits acoustic ultrasound waves into the target area. As the waves are reflected off moving blood, the change in the characteristics of the reflected waves is used to generate 3D data on a vein’s location. It can also differentiate between blood moving towards the heart (in veins) or away from the heart (in arteries).

The device consists of two components; a reusable unit housing the electronics and signal processing components and a disposable coupler box holding a reflector and needle guide.

As the device is passed over a patient’s arm or leg, a thin acoustic beam is emitted from the transducer into the reflector. The reflector directs the ultrasonic waves into the skin at a slight angle. When a vein is detected, an alarm is triggered and medics can insert the needle.

The technique has been used in large hospital-based ultrasound systems for some time. But the design of the new system has made it sufficiently portable and economical for field use for the first time. Existing hospital-based multifunction ultrasound diagnostic tools can cost upwards of $20,000. The target cost of the electronics component of the new device is $1,000 and the disposable part just $1 or $2.

“The electronics part was harder than we were expecting. We were working to a very tight budget and had to use small components that could be held in one hand,” says Michael Gray, technical spokesman for the project. “We used a single transducer to transmit and receive the sound that scatters back. It was a small circuit so we had to build an isolated switch.”

The patent pending vein finder has so far proven successful on phantom tissue, a simulated model of human tissue and blood vessels. The next step will be to adapt the device for human trials over the next five or six months. Further development is necessary as the scattering from an actual arm is more complex. The signal from the blood vessels is weaker and requires more signal processing.