Effect of continuous infusion of norepinephrine on maternal pelvic and fetal umbilical blood flow in pregnant sheep

The effect of induced maternal hyperthermia (1.5 degrees C rise over 60 min) on the uterine and umbilical circulations was examined in two groups of chronically instrumented pregnant sheep. Hyperventilation occurred in both groups. In the group in which the resultant respiratory alkalosis was untreated (N = 5), uterine blood flow decreased to 53 +/- 3% (mean +/- SE; P less than 0.01) of control at maximal maternal temperature. Umbilical blood flow also decreased 30 +/- 6% (P less than 0.01) below control levels. In the other group, normocapnia was maintained (N = 4). Uterine blood flow decreased in this group to 75% +/- 2% (P less than 0.01) of control levels, butumbilical blood flow did not significantly change. There was no significantchange in maternal or fetal mean arterial pressure during hyperthermia ineither group. Thus, maternal hyperthermia per se results in a significant decrease in uterine blood flow primarily through an effect on uterine vascularresistance, but without a concomitant change in umbilical blood flow.

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Altered umbilical blood flow after treatment with betamethasone in compromised preterm pregnancies

Journal of the Society for Gynecologic Investigation ◽

10.1016/s1071-5576(97)86424-6 ◽

1998 ◽

Vol 5 (1) ◽

pp. 123A-123A

Author(s):

L BAKER ◽

E WALLACE

Keyword(s):

Blood Flow ◽

Umbilical Blood ◽

Umbilical Blood Flow

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Placental transfer as a function of uterine blood flow

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1982.242.3.h429 ◽

1982 ◽

Vol 242 (3) ◽

pp. H429-H436 ◽

Cited By ~ 2

Author(s):

R. B. Wilkening ◽

S. Anderson ◽

L. Martensson ◽

G. Meschia

Keyword(s):

Blood Flow ◽

Placental Transfer ◽

Appreciable Effect ◽

Uterine Blood Flow ◽

Placental Perfusion ◽

Umbilical Blood ◽

Norepinephrine Infusion ◽

Umbilical Blood Flow ◽

Clearance Level ◽

Different Levels

The effect of variations of uterine blood flow (F) on placental transfer was examined in six chronic sheep preparations by measuring the placental clearances of ethanol (CE) and antipyrine (CA) at different levels of F. Norepinephrine infusion, hemorrhage, and occlusion of the terminal aorta were used to reduce F below normal. The reduction of F had no appreciable effect on umbilical blood flow (f). In each ewe, CE significantly correlated with F. The CE vs. F relationship at constant f was curvilinear with convexity toward the clearance axis. Regression analysis showed that the equation 1/CE = 1/.911 F + 1/.831 f could account for most of the CE variance (r2 = 0.97). Implicit in this relation is the concept that, given a certain level of placental perfusion, an F/f ratio congruent to 1 is optimal for the exchange of highly diffusible inert molecules between mother and fetus [CE/(F + f) was maximum at F/f = 0.955]. CA was not significantly different from CE at low clearance level but became smaller than CE at clearance values greater than 300 ml/min. This suggests that a high rates of perfusion placental permeability was a factor in limiting CA.

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