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Hand warmer makes blood sampling easier (6/11/98)

Three inventors from The University of Texas Health Science Center at San Antonio have patented a device that increases circulation to the hand, making it easier for blood samples to be drawn.

John Prokopchak, Mary Crowley and Frank Quijano of the department of instrumentation services were issued U.S. Patent No. 5,278,142 earlier this year. The title is "Method and Apparatus of Increasing Venous Blood Flow to the Hand."

The warmer applies heat in a safe manner to allow blood vessels to dilate before blood drawing. The apparatus already is being used in diabetic patients who have poor circulation in their extremities.

"The patient puts a hand inside the box and is exposed to warm air circulated by a fan," Quijano said. "In 30-60 seconds, the heat makes the veins stand out."

The device generates a temperature of 58 degrees Celsius (or 136 degrees Fahrenheit). "It sounds hot," Crowley said, "but really it's a nice, warm wind. It is pleasant."

"The key is the circulating air," Quijano said. "Sticking one's hand into 136-degree water would not be pleasant, but sticking it into gently moving air is comfortable."

The warmer can be adapted for feet as well, Crowley said, adding that several patients with arthritis have wanted to know how to get one.

Diabetes researchers headed by Dr. Ralph DeFronzo, professor of medicine at the Health Science Center, brought the need for such a device to instrumentation services.

"We need to acknowledge Dr. DeFronzo for his help in setting up the study parameters," Quijano said. "He supported the project in its early stages, and instrumentation services picked up the tab for the rest of the development. The cost of each prototype was about $3,000."

The hand warmer is about the size of an aquarium and has clear sides like a fish tank. Patients stick their hands through a plastic port assembly on one end.

Coiled inside the clear plastic sides is a 12-foot, continuous, 313-watt heating tape. A small fan circulates the heat. The warmer includes several safety controls so that the patient suffers no discomfort.

"It's clear so that the nurse or doctor or therapist can observe the veins. Some people's veins dilate faster than others' veins," Prokopchak said. "People with lower body fat will be faster. The elderly will be faster."

The hand warmer allows blood samples drawn from veins in the wrist to look more like arterial (or oxygenated) blood, with hormonal and metabolic levels that more closely approximate arterial blood than venous (or non-oxygenated) blood. The warmer increases blood flow in the hand, reducing the chance of tissue uptake of sugars, hormones and other ingredients that would skew blood measurements.

The patented hand warmer is actually the fifth prototype created by the inventors. "The first warmer was made of wood but you could not see the patient's hand," Quijano said. "The second prototype was made of acrylic plastic that warped too much in the heat. We have gone to a different plastic that can withstand the heat. We improved the safety features as we went along."

The technology has not yet been licensed. However, the warmers will be displayed at the South Texas Health & Medicine Expo '98 set for June 26-28 at the San Antonio Convention Center.

This is the first patent for staff from instrumentation services. "We have gained valuable insight into the steps of the patent process, and next we will focus on technology licensing," Quijano said.

After filing request for a patent, the inventors were called before the patent examiner only one time. In most cases, patent applicants are called before the examiner multiple times.

After the hand warmer is licensed, it will be re-engineered to suit the licensee's manufacturing efficiencies, Quijano said. Once the product hits the market, the cost of one warmer likely will be in the neighborhood of $3,000. The three inventors hope that it will become a staple item in clinics, blood banks and hospitals - indeed, anywhere that blood is drawn routinely.

Contact: Will Sansom, (210) 567-2570