Measuring blood oxygen—
small device does big job
It’s a little box that fits in your hand, weighs about 4 pounds and runs on batteries. Is it a calculator? A tape recorder? A TV remote control?
No, it’s an ‘oximeter,’ a device invented at the Health Science Center and used for measuring the blood oxygen and hemoglobin levels of patients in intensive care units and cardiac catheterization laboratories.
"Each day, scores of patients in hundreds of U.S. hospitals and 18 other countries have their disorders diagnosed with oximeters designed and developed here," said co-inventor A. P. Shepherd, PhD, professor of physiology at the Health Science Center. He and John Steinke, PhD, formerly of physiology, applied basic research into the optical properties of blood to develop the oximeter, which hit the market in 1993.
The device shines light through blood samples at different wavelengths and computes the absorption of each wavelength. "By measuring how much light is absorbed at each wavelength, we can deduce the percentage of hemoglobin saturated with oxygen and the oxygen content of each blood sample," Dr. Shepherd said. Hemoglobin is the oxygen-carrying component of whole blood.
"In the case of a cardiac cath lab, they use this instrument to diagnose problems such as atrial septal defect (a hole in the wall between two chambers of the heart) and other congenital abnormalities," Dr. Shepherd stated.
Conventional oxygen-measuring devices stand 2 feet tall and weigh 50 pounds. The Health Science Center’s oximeter is lightweight and portable, less expensive, faster and easier to maintain than conventional instruments. "It’s a piece of high-tech, but miniaturized, equipment," Dr. Shepherd noted. "It is a complete digital computer—the user just doesn’t realize he has a complete computer in his hand."
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