TIMING OF EXPOSURES IN ULTRASONIC HEMORRHAGE OF MURINE LUNG

Pressure thresholds for lung hemorrhage by exposure to low-temporal-av erage-intensity, pulsed ultrasound are of the order of 1 MPa. Earlier evidence suggested that ultrasound modifies the tissue over short peri ods of time in such a way that the nonthermal action of ultrasound is enhanced. Measurements of thresholds (1) for hemorrhage and (2) for pe netration of the hemorrhage through the murine lung in which a given ' 'on-time'' was presented to the tissue over periods of time up to 3 mi n support the hypothesis.