Seattle Times September 20, 2006
Using ultrasound for war wounds
By Luke Timmerman
Sometimes late at night, a team of elite physicists and engineers in Seattle's Belltown neighborhood gathers around its conference room and reflects on the photos it has seen of U.S. troops bleeding to death in Iraq.
The images help fire up these physicists and engineers to do the most challenging and creative work of their lives.
Their mission is to invent a device that sounds straight out of "Star Trek": a lightweight ultrasound machine for soldiers on the battlefield to detect and stop internal bleeding in minutes.
It's an assignment that would advance ultrasound technology on several fronts, far beyond anything now available. Yet even if they succeed, such a device is at least four years away from being available.
The researchers at AcousTx, a small ultrasound company in Seattle, are funded by a four-year contract, worth up to $30 million, from the U.S. Defense Advanced Research Projects Agency (DARPA).
To underscore the pressing need, the agency gave another $21 million to a competing group, a partnership of Philips Research and the University of Washington's Center for Industrial and Medical Ultrasound.
"If this were to work, just think — just think — about the value it would have as a lifesaving device," said Michael Sekins, AcousTx vice president of research and development.
His colleague, Randy Serroels, finished the thought: "People will come home that don't come home today."
The project has added urgency because so many troops have been injured in Iraq, particularly by improvised explosive devices. There were 2,562 U.S. troops killed in Iraq and 19,157 wounded as of July 31, according to GlobalSecurity.org, a military research firm.
Even body armor doesn't protect soldiers from wounds to the limbs, and blood loss from such wounds is ranked the No. 1 cause of preventable battlefield death, according to a 2004 study published in Infantry, an Army magazine.
The problem isn't an abstraction for AcousTx. To better understand it, the researchers watch TV footage from the battlefield and study graphic Army photos that aren't released to the public. Combat medics from Madigan Army Medical Center have discussed with them what soldiers are up against in the field.
There are two major kinds of injuries that battlefield medics often see, according to DARPA. When a bomb severs a major artery, a soldier can go into shock in as little as 30 seconds and soon die. But bombs can also cause slow internal bleeding that may go unnoticed but kill over a matter of hours. DARPA wants a device that can save both the "fast" and "slow" bleeders.
Ultrasound was picked as the technology due to its potential to detect bleeding with low-power, high-resolution images, then dial up to high-powered settings that can heat and cauterize wounds.
The military envisions the device as a cuff, like the ones used to measure blood pressure, which is lined with hundreds of small ultrasound transducers. The cuff must be versatile enough to be wrapped a around a small woman's upper arm, or a large man's thigh. To minimize the pressure on a sensitive arm or leg, it can weigh no more than 6.6 pounds.
The supporting electronics and battery power must be light and compact enough to fit in a rucksack. It must be automated so that a soldier with limited training can use it. Furthermore, it must be durable enough to withstand dust storms and searing desert heat. It must be tough enough to bounce around in the back of a Humvee.
The challenges are daunting, scientists say. Lightweight ultrasound machines for diagnostic purposes have been around for years, but require a trained operator.
Therapeutic ultrasound is still a field in its research infancy. Scientists have run hundreds of animal experiments using high-intensity, focused ultrasound beams to seal internal bleeding, but no one has yet developed a system that is FDA-approved and widely used in humans.
No one has yet invented transducers with the twin capability of receiving diagnostic ultrasound images, then delivering high-intensity ultrasound bursts, up to a million times more intense, to stop bleeding.
AcousTx won its piece of the contract for its expertise in high-intensity-focused ultrasound and partnered with Siemens Research for its skills with ultrasound images.
Talents honed at Therus
Many of the AcousTx engineers honed their talents for years at Seattle-based Therus, a sister company developing a machine that uses ultrasound to seal punctures to the femoral artery.
That artery is punctured every time a cardiologist inserts a catheter into a patient for angioplasty or a stent, and the puncture must be compressed, stitched or plugged to stop bleeding. Therus has shown in more than 100 patients in Germany that its system can seal the puncture in 10 to 20 seconds.
But the DARPA project is much more ambitious.
Serroels, the vice president and general manager of AcousTx, said the new military project is pushing the boundaries of what's possible with ultrasound.
For example, diagnostic ultrasound transducers send low-powered waves into the body, in broad brushstrokes, then measure the echoes to create an image. Therapeutic ultrasound waves, in contrast, are high-powered, short one-way bursts that focus down like a magnifying glass into a point the size of a grain of rice.
Not only must the team combine these capabilities, it must make the system automated and miniaturized. Accuracy is essential because if the therapeutic beams miss, they could damage healthy tissue.
But if it works for the military, AcousTx hopes to go on to develop a commercial version for paramedics and emergency rooms. Whether such a device could ever be cost-effective is unknown.
"It's a challenge, it really is," Serroels said. "DARPA sets the bar very high, and they're asking us to push the limits. But I tell you what, that's what engineers live for, challenging efforts."
One ultrasound expert not involved with the project, Jens Quistgaard, said, "I wouldn't put it in the crazy category, but I would put it in the highly technically challenging category."
Lawrence Crum, director of the University of Washington's Center for Industrial and Medical Ultrasound, is part of the competing effort funded by DARPA.
Crum was the principal investigator of a previous DARPA-sponsored project for diagnostic ultrasound in the mid-'90s, which gave rise to another Seattle-area company, SonoSite.
On that project, DARPA asked him to develop an ultrasound machine as small as a cellphone with a transducer that could detect plastic shrapnel, which was becoming common in land mines.
Crum's commercial partner, Bothell-based ATL Ultrasound, spun out SonoSite to develop a commercial version.
Ultimately the machines were similar in size to a laptop computer, but the military purchased hundreds and still uses them.
Crum said he can imagine this project unfolding in a similar way.
Plan is difficult
He said he has a clear plan to tackle the problem, but it will be difficult. If the research leads to a commercial product, Crum said, he can envision something about the size of a flashlight, which a skilled surgeon or paramedic could use without all the automation required by the military.
Crum said DARPA has staying power and a history of being flexible enough to adapt to technologies that evolve in unpredictable ways.
"This is a great idea, so what could happen is, you try to do it, and maybe settle for something less, but that is still of great value," Crum said.
Sekins said the AcousTx team has spent a lot of time "burning the midnight oil" to hone its strategy. But he emphasized the engineers are also motivated by the potential to save lives.
"This is a technical whiz-bang project," Sekins said. "But this is also one of those things where if you can do it, it is really an achievement."
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