Finding A Vein

Finding a vein, necessary for administering intravenous solutions, can often be difficult. A new device, called a Vein Contrast Enhancer (VCE), uses sensitive infrared sensing to find the vein beneath the skin and then also projects the rather spooky vein image back onto the patient's wrist. This makes it appear as if the veins were lying right on top, making it easy for a nurse to make an injection.

How does it work? An array of light emitting diodes shines infrared light at the subject, and one depends on the fact that red blood cells scatter light differently from surrounding fatty tissue. The scattered light passes through some filters and then is captured by a CCD TV camera, processed by computer, and rendered as a sort of movie at a rate of 30 frames per second. These images can be projected onto the subject through a careful aligning process to register the surface projection with subcutaneous anatomy (see figure at Physics News Graphics).

Herbert Zeman and his colleagues at the University of Tennessee Health Science Center in Memphis have done extensive clinical trials with VCE devices and are now doing trials with the projection capability. The general spatial resolution of the process is about 0.1 mm. Veins as deep as 8 mm have been imaged. This work is being presented at this week's Frontiers in Optics meeting in Rochester, co-sponsored by the Optical Society of America (OSA) and the American Physical Society (APS). (See also http://www.conenhill.com/)