Fetal oxygenation and Doppler ultrasonography of cardiovascular hemodynamics in a chronic near-term sheep model

We hypothesized that a decrease in fetal oxygenation without acidemia in a near-term fetal sheep leads to cardiovascular hemodynamic changes that are detectable by Doppler ultrasonography. Twelve ewes and fetuses were instrumented at 112 to 127 days of gestation. After a 5-day recovery period, exper...

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Bibliographic Details
Published in:American journal of obstetrics and gynecology 2006-02, Vol.194 (2), p.542-550
Main Authors: Mäkikallio, Kaarin, Erkinaro, Tiina, Niemi, Niina, Kavasmaa, Tomi, Acharya, Ganesh, Päkkilä, Mervi, Räsänen, Juha
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Blood Gas Analysis
Cardiac Output - physiology
Cardiovascular System - embryology
Doppler ultrasonography
Female
Fetal sheep
Fetus - physiology
Gynecology. Andrology. Obstetrics
Heart Rate - physiology
Hemodynamics - physiology
Medical sciences
Oxygen
Physiology
Pregnancy
Pulmonary Artery - physiology
Pulsatile Flow - physiology
Sheep
Stroke Volume - physiology
Ultrasonography, Doppler
Ultrasonography, Prenatal
Vascular Resistance - physiology
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Summary:We hypothesized that a decrease in fetal oxygenation without acidemia in a near-term fetal sheep leads to cardiovascular hemodynamic changes that are detectable by Doppler ultrasonography. Twelve ewes and fetuses were instrumented at 112 to 127 days of gestation. After a 5-day recovery period, experiments were performed with general anesthesia. Uterine and placental volume blood flows and fetal arterial and venous blood pressures were measured. Fetal cardiovascular hemodynamics was assessed by Doppler ultrasonography. All the measurements were performed at baseline, during fetal hypo-oxygenation, and at recovery phase. A drop in fetal P o 2 was related to increased ( P < .05) weight-indexed right ventricular and combined cardiac outputs and proximal branch pulmonary artery pulsatility index values. The increase in proximal branch pulmonary artery pulsatility index values correlated ( R = .59; P < .05) with the decrease in fetal oxygen saturation. In the aortic isthmus, the time-velocity integral ratio between antegrade and retrograde blood flow components decreased ( P < .05) when fetal P o 2 dropped. During decreased fetal oxygenation Doppler ultrasonography demonstrated increased fetal cardiac output and pulmonary arterial vascular impedance and a relative increase in the retrograde blood flow component in the aortic isthmus.
ISSN:0002-9378
1097-6868
DOI:10.1016/j.ajog.2005.08.028