Thermal and heart rate response to ultrasonic exposure in the second and third trimester dog fetus.
A total of 39 fetuses from five pregnant dogs were used in this study. Following pentobarbital anesthesia of the dams the gravid uterus was exposed and partially exteriorized. Fetal and maternal electrocardiograms were recorded, along with fetal abdominal temperatures, during ultrasound exposures of 3.4 MHz and 2, 4, 6, 8 or 12 W/cm2 (continuous wave), spatial average intensities, for 6 minutes. Baseline fetal abdominal temperatures were 35.2 +/- 1.5 (SD) degrees C. Baseline fetal heart rates were 176.8 +/- 4.3 (SD) beats per minute. These studies indicate that the product of intensity and time of exposure, under the conditions of these experiments, is directly related to increases in fetal abdominal temperature and fetal heart rate.
D000818:Animals; D001831:Body Temperature; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D011247:Pregnancy; D011270:Pregnancy, Animal; D014465:Ultrasonics