Potential for HIFU extends to treating lung injuries

The birthplace of hand-carried ultrasound is now grooming another innovative development, this one using ultrasound in therapy rather than diagnosis.

Researchers at the University of Washington, where early work led to the development of the first hand-carried ultrasound prototype, are looking into an ultrasound device that cauterizes lung tissue, stops bleeds, and seals air leakage typically encountered in trauma cases. The work addresses an application widely thought unapproachable with this technology.

Because the lungs are essentially a collection of air sacs, the transmission of ultrasound, which requires a liquid environment, is typically blocked. The Washington preclinical experiments, published in the June issue of the Journal of Trauma: Injury, Infection, and Critical Care, demonstrate that punctures on the lung's surface, where injuries usually occur, can be healed with ultrasound therapy.

"The results are really impressive," said Shahram Vaezy, PhD, an associate professor of bioengineering at the University of Washington.

The UW Center for Industrial and Medical Ultrasound has been exploring the use of ultrasound for more than a decade. Vaezy cautions that the technology, as applied to the lungs, is still in its early stages.

In the UW team's application, HIFU beams are focused at a particular spot on the lungs, creating enough heat to seal the injury. Preclinical testing reported in the Journal of Trauma involved incisions in pigs that caused parenchymal hemorrhage and air leakage from the lungs. Bleeding was stopped and air leaks sealed in all cases, some as quickly as 10 seconds, others as long as four minutes. Treatment time did not depend on the length or depth of the incisions, of which more than 95% were hemostatic within two minutes of HIFU application.

Vaezy said the research proved that the HIFU can penetrate deep into the body and deliver energy to the bleeding very accurately, suggesting that ultrasound might replace what is now an invasive procedure.

Lung injuries are common in trauma cases, because the large chest surface often is exposed to crushing or puncture wounds, said Dr. Gregory Jurkovich, chief of trauma at Harborview Medical Center in Seattle and a UW professor of surgery. The busy trauma room in Harborview admits about two patients with bleeding lungs daily.

Often the bleeding can be stopped by packing the wound and applying pressure. In other cases, doctors must insert a catheter to drain the blood and deflate the lung, so the wound can heal. In about one in 10 cases, however, neither method is successful and repairs must be done surgically.

The UW research shows that in these difficult cases, HIFU has at least the potential to stop the bleeding and the air leaks.