THRESHOLDS FOR ULTRASONICALLY INDUCED LUNG HEMORRHAGE IN NEONATAL SWINE

Citation
R. Baggs et al., THRESHOLDS FOR ULTRASONICALLY INDUCED LUNG HEMORRHAGE IN NEONATAL SWINE, Ultrasound in medicine & biology, 22(1), 1996, pp. 119-128
Citations number
18
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging",Acoustics
ISSN journal
03015629
Volume
22
Issue
1
Year of publication
1996
Pages
119 - 128
Database
ISI
SICI code
0301-5629(1996)22:1<119:TFUILH>2.0.ZU;2-6
Abstract
The threshold for generation of lung hemorrhage in adult mice by pulse d ultrasound has been shown to be approximately 1 MPa at the surface o f the lung (10-mu s pulse and a carrier frequency of 2 MHz), This inve stigation used neonatal swine to determine if the findings for mice ca n be generalized to other species, After exploratory observations, the inverse sampling method was used in a primary study (22 animals, 88 e xposure sites) to determine the threshold for lung hemorrhage in neona tal swine, The primary study was followed by a separate confirmation s tudy (13 animals, 48 exposure sites), testing the conclusions of the f irst study and comparing damage at subthreshold levels with sham-expos ed animals, A separate investigation explored the histological nature of tissue damage at suprathreshold levels, A 2.3-MHz focused transduce r (10 mu s at 100-Hz pulse-repetition frequency) was incremented verti cally for a distance of 2 cm over the chest of the subject for a total exposure period of 16 min, Animals were euthanized and lungs were sco red by visual inspection for numbers and areas of gross hemorrhages. T he threshold level for hemorrhage was approximately 1.5 MPa peak posit ive pressure in water at the surface of the animal or, at the surface of the lung, 1.1 MPa peak positive pressure, 1 MPa fundamental pressur e, 0.9 MPa maximum negative pressure, 25 W cm(-2) pulse average intens ity or a mechanical index of 0.6, These values are essentially the sam e as those reported for adult mice.