Non-invasive quantitative measurement of blood flow and estimation of vascular resistance by the Doppler ultrasound method. Methodological studies and clinical application on the fetus and the transplanted kidney allograft.
The introduction of ultrasound 25 years ago was an important improvement and represented a significant step forward in the examination of several organs, especially in the abdomen. During the last 10 years it has been possible to combine Real-Time ultrasound with Doppler ultrasound, thus gaining information on the blood flow and vascular resistance in several organs. The ultrasound method has great advantages; it is non-invasive, can be repeated whenever needed, can be performed bed-side and is inexpensive to use. The present study was undertaken to examine whether the method could be used to diagnose several pathological conditions relevant to the obstetrician and the nephrologist. Before clinical application was performed, the theories behind the ultrasound Doppler principle and the possibilities and limitations of the equipment available for examinations were carefully examined and the method was improved in several important aspects. The precision and accuracy of the improved method was tested in-vitro and in-vivo studies. It was shown that the ultrasound Doppler method has now been developed to an acceptable degree of precision and accuracy for use in scientific investigations and daily clinical routine. The method was then used to examine the fetal and the renal allograft hemodynamics. Reference values for quantitative blood flow in the fetal aorta and the umbilical vein, and for vascular resistance in the normal fetus and the renal allograft were provided, and the method was used to describe hemodynamic changes during several pathological conditions. Some hitherto unknown physiological and pathophysiological variations of blood flow and vascular resistance were found. Thus it was demonstrated that fetal hemodynamics are affected during untreated maternal hypertension in pregnancy and changed towards normal during treatment of the mother, and that renal vascular resistance is increased during rejection of the allograft and normalized following treatment. Furthermore, it was demonstrated that the ultrasound Doppler examination is of diagnostic value when dysfunction of the renal allograft is present.
Rasmussen
K
K
Department of Obstetrics and Gynaecology, Herlev University Hospital.
D000328:Adult; D001775:Blood Circulation / Q000502:physiology*; D001808:Blood Vessels / Q000000981:diagnostic imaging*; D005260:Female; D005333:Fetus / Q000648:ultrastructure; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging; D016030:Kidney Transplantation / Q000502:physiology; D011247:Pregnancy; D014465:Ultrasonics; D014463:Ultrasonography / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods; D014655:Vascular Resistance / Q000502:physiology*