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Background Operative management of parenchymal lung injury can be complicated by persistent hemorrhage and air leak, which might require resection. Techniques that preserve parenchyma are associated with improved survival. High-intensity focused ultrasound (HIFU) has been demonstrated as a useful method for hemostasis in experimental solid organ injuries. We wished to investigate whether this could be applied to lung injuries. Methods An intraoperative HIFU device (frequency of 5.7 MHz, acoustic power of 65 W), equipped with a titanium coupler, was used. Incisions (average length of 2.5 cm, and depth of 5 mm) were made in the lungs of 11 pigs, which created both parenchymal hemorrhage and air leakage. In treatment experiments, 70 incisions were sealed with HIFU. The HIFU application started within 10 seconds of inducing the injury. Hemostasis was assessed by visual observation of sealed incisions. The possible air leakage was determined by submersing the sealed incision under the layer of water and observing for air bubble formation. In control experiments, five incisions were left untreated to monitor air leaks and bleeding for 2 minutes. Results Hemostasis and pneumostasis (sealing of air leaks) of the treated incisions were achieved in 51 +/- 37 seconds (mean +/- SD) (range of 10-210 seconds) of HIFU application time. Over 95% of incisions were hemostatic within 2 minutes of HIFU application. The treatment time was not dependent on the incision length or depth. In control experiments, the air leaking and bleeding were still present at 2 minutes after the injury. Conclusion Intraoperative HIFU might provide an effective method of hemostasis and control of air leaks from lacerations caused by trauma.