LACK OF LUNG HEMORRHAGE IN HUMANS AFTER INTRAOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHY WITH ULTRASOUND EXPOSURE CONDITIONS SIMILAR TO THOSE CAUSING LUNG HEMORRHAGE IN LABORATORY-ANIMALS

This study investigated the phenomenon of ultrasoni cally induced lung hemorrhage in humans. Multiple experimental laboratories have shown t hat diagnostic ultrasound exposure can cause hemorrhage in the lungs o f laboratory animals. The left lung of 50 patients (6 women, 44 men, m ean age 61 years) was observed directly by the surgeon after routine i ntraoperative transesophageal echocardiography was performed. From man ufacturer specifications the maximum derated intensity in the sound fi eld of the system used was 186 W/cm(2), the maximum derated rarefactio nal acoustic pressure was 2.4 MPa, and the maximum mechanical index wa s 1.3. The lowest frequency used was 3.5 MHz. This exposure exceeds th e threshold found for surface lung hemorrhage seen on gross observatio n of laboratory animals. No hemorrhage was noted on any lung surface b y the surgeon on gross observation. We conclude that clinical transeso phageal echocardiography, even at field levels a Little greater than t he reported thresholds for lung hemorrhage in laboratory animals, did not cause surface lung hemorrhage apparent on gross observation. These negative results support the conclusion that the human lung is not ma rkedly more sensitive to ultrasound exposure than that of other mammal s.