Effects of pulsed ultrasound on sphenoid bone temperature and the heart rate in guinea-pig foetuses.
Temperature increase induced by exposure to unscanned pulsed ultrasound at an intensity (I(SPTA)) 2.82 W/cm2 was measured in the brain adjacent to the sphenoid bone of foetal guinea-pigs in late gestation under in vitro and in vivo (in utero) conditions. After 120 s exposure a mean temperature increase of 2.6 degrees C was measured in vitro. Removal of the overlying parietal bones increased this value to 5.2 degrees C. Mean temperature increases at the sphenoid bone recorded in utero were 1.5 degrees C live and 2.0 degrees C post mortem. Measurement of foetal ECG showed that ultrasound-induced heating of the hypothalamic region did not significantly alter foetal heart rate.
Horder
M M
MM
Dept. of Veterinary Clinical Sciences, University of Sydney, NSW, Australia.
Barnett
S B
SB
Vella
G J
GJ
Edwards
M J
MJ
D000818:Animals; D001831:Body Temperature; D004562:Electrocardiography; D005260:Female; D005865:Gestational Age; D006168:Guinea Pigs; D006340:Heart Rate, Fetal; D007031:Hypothalamus / Q000196:embryology / Q000502:physiology; D011247:Pregnancy; D013100:Sphenoid Bone / Q000196:embryology* / Q000502:physiology; D018617:Ultrasonography, Doppler, Pulsed / Q000009:adverse effects*; D016216:Ultrasonography, Prenatal / Q000009:adverse effects*