ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4aPA7. Biological effects of lithotripter fields.

Diane Dalecki

Sally Z. Child

Carol H. Raeman

Edwin L. Carstensen

Dept. of Elec. Eng. and the Rochester Ctr. for Biomedical Ultrasound, Univ. of Rochester, Rochester, NY 14627

Lithotripsy has become a common procedure for the treatment of kidney stones. Fields of lithotripters are capable of producing both stone distintegration and damage to soft tissues. Thresholds for biological effects of lithotripter fields include hemorrhage in mammalian lung (~1.5 MPa), kidney (3--5 MPa), and intestine (1--3 MPa), malformations in the chick embryo (<10 MPa), premature ventricular contractions in the frog heart (5--10 MPa), and killing of Drosophila larvae (<1 MPa). Tissues containing gas bodies are particularly susceptible to damage. Pulsed ultrasound can also produce comparable soft-tissue damage and the similarity of threshold pressures for lithotripter and pulsed ultrasound exposures suggests that the same mechanisms may be involved in both phenomena. Cavitation and purely mechanical forces have been investigated as possible mechanisms for these bioeffects.