Ultrasound can do more than peer inside the body
DOCTORS may eventually use sound waves to halt haemorrhages deep within the body without having to slice into a patient.
There is no widespread method for stopping internal bleeding without surgery, which is itself risky. As an alternative, some researchers are hoping to use ultrasound to pinpoint, heat and cauterise internal wounds. But cooking tissue in that way is too dangerous if bleeding occurs in areas such as the brain, or if the problem is hard to pinpoint and doctors need to treat a large area of the body.
Now a team from the University of Washington in Seattle has discovered that high-intensity focused ultrasound beams can accelerate natural clotting, and stop bleeding without heating up tissue.
Sound waves make blood move around more than usual. This activates platelets by tricking them into thinking they are flowing through an open wound. In lab experiments, the new method activated platelets, causing them to stick to membranes and each other, both necessary steps for clots to form.
Such a technique could be a welcome or even life-saving option when cauterising is too dangerous. "It's a phenomenon we are really excited about," says team member Lawrence Crum. The researchers have also found that clotting occurs more rapidly if gas-filled microbubbles called ultrasound contrast agents are present. The bubbles are often injected into tissue as an aid for ultrasound imaging.
The next step, according to team member Wayne Chandler, will be to learn how to optimise the technique before moving on to animal then human tests, which could take place in the next few years.
Author: Mark Schrope
New Scientist issue: 3 June 2000
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