Terry Blumenthal is not a medical device designer, but he has an important message for engineers who design defibrillators. The Wake Forest University psychologist is working with cardiologist Charles Swerdlow to find ways of reducing the painful electric shock administered by defibrillators when they activate. "We considered using weaker electric shocks, but that didn't work," says Swerdlow. "Then we tried changing the shape of the waveform, but that has not yet been successful," he explains. They eventually found that when a painless electric "pre-pulse" precedes a painful electric shock, the pre-pulse seems to reduce the body's startle response and minimize pain. "The pre-pulse interrupts everything, including the subsequent processing of pain," says Blumenthal. "It diminishes the neural circuits' ability to respond to subsequent painful stimulus," he says. Testing the hypothesis involved delivering 150V shocks to volunteers, who then rated the shock's painfulness with and without pre-pulses. Although volunteers received the same shock, the painfulness was rated lower with the pre-pulse. "There may be a variety of ways to integrate these finding into other applications using sound, sight, and other modalities," says Blumenthal. For more information, e-mail firstname.lastname@example.org.
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