ESTIMATION OF UTERINE BLOOD FLOW IN NORMAL HUMAN PREGNANCY AT TERM 1

Normal human pregnancy requires a dramatic increase in uteroplacental blood flow which is achieved by a transformation in the geometry of uterine spiral arteries, a key element in this blood supply system. The transformation is mediated by trophoblast invasion directed at converting a portion of the spiral artery into an open funnel, thereby greatly reducing resistance to flow. The converted portion lies within the depth of the decidua and part of the myometrium. Insufficient depth of trophoblast invasion in early pregnancy predisposes to inadequate perfusion of the developing placenta andfetus and may lead to preeclampsia, fetal growth restriction and preterm delivery, sometimes referred to as the "Great Obstetrical Syndromes". We examine the hemodynamic consequences of spiral artery transformation in human pregnancy and the relationship between the degree of transformation and the corresponding change in flow rate and resistance to flow. We identify two key variables in determining the hemodynamic change: the longitudinal converted fraction of the spiral artery and the relative downstream diameterof the open funnel. Our results indicate that there is a critical threshold in the value of the converted fraction required to achieve the marked increase in uteroplacental blood flow in normal pregnancy. This finding validates common clinical observations that the depth of trophoblast invasion reflects the "adequacy" of the increase in uteroplacental blood supply required in normal human pregnancy. Our results provide a quantitative measure of that adequacy and may serve as a future diagnostic marker for high-risk pregnancy.

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CSE Tied to Brief Drop In Uterine Blood Flow

Ob Gyn News ◽

10.1016/s0029-7437(07)70603-1 ◽

2007 ◽

Vol 42 (13) ◽

pp. 23

Author(s):

Kate Johnson

Keyword(s):

Blood Flow ◽

Uterine Blood Flow

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DEPENDENCE OF UTERINE BLOOD FLOW FROM THE FUNCTIONAL ACTIVITY OF OVARIES WITH ADENOMYOSIS

The Journal of scientific articles Health and Education millennium ◽

10.26787/nydha-2226-7425-2017-19-11-18-23 ◽

2017 ◽

Vol 19 (11) ◽

pp. 18-23

Author(s):

A.F. Arutyunyan ◽

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A.R. Protsenko ◽

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Keyword(s):

Blood Flow ◽

Functional Activity ◽

Uterine Blood Flow

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Behavioral activity during prolonged hypoxemia in fetal sheep

Journal of Applied Physiology ◽

10.1152/jappl.1988.65.6.2420 ◽

1988 ◽

Vol 65 (6) ◽

pp. 2420-2426 ◽

Cited By ~ 49

Author(s):

A. D. Bocking ◽

R. Gagnon ◽

K. M. Milne ◽

S. E. White

Keyword(s):

Blood Flow ◽

Eye Movements ◽

Normal Incidence ◽

Behavioral Activity ◽

Uterine Blood Flow ◽

Fetal Sheep ◽

Pregnant Sheep ◽

Fetal Breathing ◽

Fetal Breathing Movements ◽

Internal Iliac

Experiments were conducted in unanesthetized, chronically catheterized pregnant sheep to determine the fetal behavioral response to prolonged hypoxemia produced by restricting uterine blood flow. Uterine blood flow was reduced by adjusting a vascular occluder placed around the maternal common internal iliac artery to decrease fetal arterial O2 content from 6.1 +/- 0.3 to 4.1 +/- 0.3 ml/dl for 48 h. Associated with the decrease in fetal O2 content, there was a slight increase in fetal arterial PCO2 and decrease in pH, which were both transient. There was an initial inhibition of both fetal breathing movements and eye movements but no change in the pattern of electrocortical activity. After this initial inhibition there was a return to normal incidence of both fetal breathing movements and eye movements by 16 h of the prolonged hypoxemia. These studies indicate that the chronically catheterized sheep fetus is able to adapt behaviorally to a prolonged decrease in arterial O2 content secondary to the restriction of uterine blood flow.

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Anesthetic Techniques for Fetal Surgery

Anesthesiology ◽

10.1097/aln.0b013e318283c954 ◽

2013 ◽

Vol 118 (4) ◽

pp. 796-808 ◽

Cited By ~ 16

Author(s):

Pornswan Ngamprasertwong ◽

Erik C. Michelfelder ◽

Shahriar Arbabi ◽

Yun Suk Choi ◽

Christopher Statile ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Function ◽

Fetal Surgery ◽

Left Ventricular ◽

High Dose ◽

Anesthetic Techniques ◽

Uterine Blood Flow ◽

Fetal Cardiac Function ◽

Significant Difference ◽

Fetal Acidosis

Abstract Background: Use of high-dose inhalational anesthesia during open fetal surgery may induce maternal–fetal hemodynamic instability and fetal myocardial depression. The authors’ preliminary human retrospective study demonstrated less fetal bradycardia and left ventricular systolic dysfunction with lower dose desflurane supplemented with propofol and remifentanil IV anesthesia (SIVA). In this animal study, the authors compare maternal–fetal effects of high-dose desflurane anesthesia (HD-DES) and SIVA. Methods: Of 26 instrumented midgestational ewes, data from 11 animals exposed to both SIVA and HD-DES in random sequences and six animals exposed to HD-DES while maternal normotension was maintained were analyzed. Maternal electroencephalography was used to guide comparable depths of anesthesia in both techniques. Hemodynamic parameters, blood gas, and fetal cardiac function from echocardiography were recorded. Results: Compared with SIVA, HD-DES resulted in significant maternal hypotension (mean arterial pressure difference, 19.53 mmHg; 95% CI, 17.6–21.4; P < 0.0001), fetal acidosis (pH 7.11 vs. 7.24 at 150 min, P < 0.001), and decreased uterine blood flow. In the HD-DES group with maternal normotension, uterine blood flow still declined and fetal acidosis persisted, with no statistically significant difference from the group exposed to HD-DES that had maternal hypotension. There was no statistically significant difference in fetal cardiac function. Conclusion: In sheep, SIVA affects maternal hemodynamics less and provides better fetal acid/base status than high-dose desflurane. Fetal echocardiography did not reflect myocardial dysfunction in this model.

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