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- Title
Doppler ultrasound measurements in the central circulation of anesthetized fetal sheep during obstruction of umbilical–placental blood flow.
- Authors
Tchirikov, M.; Hecher, K.; Deprest, J.; Zikulnig, L.; Devlieger, R.; Schröder, H. J.
- Abstract
ABSTRACTObjectiveTo establish by Doppler ultrasound the effects of acute blockage of umbilical cord vessels on the fetal central circulation. DesignExperimental study in anesthetized pregnant sheep. MethodsIn 11 anesthetized pregnant sheep (0.66 of gestation), Doppler velocity profiles and/or venous flow rates were recorded in the ductus venosus, the fetal aorta, the umbilical arteries and the umbilical vein. This involved three phases. In Phase 1, the abdominal wall was closed (n = 9); Phase 2 was during fetoscopy after laparotomy (n = 8); Phase 3 was after coagulation of one of the umbilical arteries (n = 10). As an additional intervention in six fetuses, the umbilical cord was clamped for 5–15 s while blood flow velocity changes in the ductus venosus were observed. ResultsThere were no significant differences between Doppler recordings in Phases 1 and 2. During Phase 3, the pulsatiltiy index of the aorta and of the coagulated umbilical artery increased significantly. The umbilical vein blood flow rate was significantly reduced from a median of 408 (range, 243–575) mL/min/kg in Phase 1 to a median of 173 (range, 107–426) mL/min/kg in Phase 3, but the blood flow rate in the ductus venosus (median, 94; range, 56–148 mL/min/kg vs. median, 92; range, 33–237 mL/min/kg) remained unchanged. The ductus venosus/umbilical vein ratio increased from a median of 0.22 (range, 0.13–0.41) to 0.56 (range, 0.17–0.97) (P < 0.05). Compression of the cord (5–15 s) immediately reduced the time averaged maximum velocity in the ductus venosus from a mean of 51 (standard deviation, 11) cm/s to 20 (standard deviation, 6) cm/s (P < 0.001) without significant changes of the velocity profile. However, the pulsatiltiy index increased from a mean of 0.55 (standard deviation, 0.19) to 1.89 (standard deviation, 0.73) (P < 0.001). ConclusionCentral venous flows in anesthetized fetal sheep are unaffected by laparotomy and hysterotomy. Obliteration of one umbilical artery increases the ductus venosus/umbilical vein volume flow (mL/min/kg) ratio. Compression of the umbilical cord shifts down blood flow velocity profiles in the ductus venosus, and the pulsatiltiy index thus increases.
- Subjects
HUMAN abnormalities; LASER Doppler blood flowmetry; DUCTUS arteriosus; UMBILICAL cord
- Publication
Ultrasound in Obstetrics & Gynecology, 2001, Vol 18, Issue 6, p656
- ISSN
0960-7692
- Publication type
Article
- DOI
10.1046/j.0960-7692.2001.00467.x