Increase of fetal arterial blood temperature by reduction of umbilical blood flow in chronically instrumented fetal sheep

1994 ◽  
Vol 427 (1-2) ◽  
pp. 190-192 ◽  
Author(s):  
H. J. Schr�der ◽  
G. G. Power
Keyword(s):  
Blood Flow ◽  
Fetal Sheep ◽  
Blood Temperature ◽  
Umbilical Blood ◽  
Arterial Blood ◽  
Umbilical Blood Flow ◽  
Arterial Blood Temperature

Effect of graded umbilical cord compression in fetal sheep at 0.6-0.7 gestation

1991 ◽  
Vol 261 (4) ◽  
pp. H1268-H1274 ◽  
Author(s):  
H. S. Iwamoto ◽  
E. Stucky ◽  
C. M. Roman
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Umbilical Cord ◽  
Cord Compression ◽  
Plasma Norepinephrine ◽  
Fetal Sheep ◽  
Umbilical Blood ◽  
Arterial Blood ◽  
Arterial Ph ◽  
Umbilical Blood Flow

To define responses of immature fetuses to asphyxia, we occluded the umbilical cord of 11 chronically instrumented fetal sheep at 82-94 days gestation and measured hemodynamic and catecholamine responses. The fetuses became acidemic, hypoxemic, and hypercarbic: arterial pH and PO2 decreased from 7.36 +/- 0.04 and 22 +/- 3 Torr to 7.10 +/- 0.04 (mean +/- SD, P less than 0.01) and 15 +/- 4 Torr (P less than 0.01), respectively, and PCO2 increased from 56 +/- 5 to 86 +/- 8 Torr (P less than 0.01) when umbilical blood flow was reduced by 75-88%. This degree of reduction in umbilical blood flow decreased cardiac output from 606 +/- 101 to 247 +/- 67 ml.min-1.kg-1 (P less than 0.01) and blood flow to hepatic, renal, musculoskeletal, and pulmonary vascular beds. Plasma norepinephrine concentrations increased from 1,557 +/- 975 to 16,718 +/- 14,672 pg/ml (P less than 0.05) with a 75-88% reduction, but mean arterial blood pressure did not increase. The absence of a hypertensive response probably relates to the decrease in cardiac output. These data indicate that asphyxia severely compromises cardiac output and organ perfusion in the midgestation fetus.

Influence of skin temperature on central thermoregulatory control of leg blood flow

1981 ◽  
Vol 50 (5) ◽  
pp. 974-978 ◽  
Author(s):  
D. W. Proppe
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Skin Temperature ◽  
Major Influence ◽  
Papio Anubis ◽  
Vascular Conductance ◽  
Leg Blood Flow ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Arterial Blood Temperature

This study examined the influence of elevated skin temperature (Tsk) on the central thermoregulatory control of leg blood flow in five unanesthetized, chronically instrumented, resting baboons (Papio anubis and P. cynocephalus). In each experiment, mean iliac blood flow (MIBF), mean arterial blood pressure, arterial blood temperature (Tbl), and Tsk were measured, and iliac vascular conductance (IVC) was calculated. A heat exchanger was incorporated into a chronic arteriovenous femoral shunt to control Tbl. The protocol consisted of raising Tbl approximately 2.6 degrees C in thermoneutral environment (cool Tsk) an then again after Tsk had been elevated by environmental heating. A major influence of raising Tsk was the lowering of threshold Tbl at which the rise in MIBF and IVC commenced. This threshold Tbl was lowered at least 0.8 degrees C on the average. Also, over the whole range of Tbl studied (37.0-39.6 degrees C), MIBF and IVC were higher at high Tsk than at cool Tsk. Thus an elevation of Tsk significantly influences the control of skin blood flow by central thermoreceptors.

Dynamics of cardiovascular responses to repeated partial umbilical cord compression in late-gestation sheep fetus

1997 ◽  
Vol 273 (5) ◽  
pp. H2351-H2360 ◽  
Author(s):  
Dino A. Giussani ◽  
Nobuya Unno ◽  
Susan L. Jenkins ◽  
Richard A. Wentworth ◽  
Jan B. Derks ◽  
...  
Keyword(s):  
Blood Flow ◽  
Umbilical Cord ◽  
Cardiovascular Responses ◽  
Cord Compression ◽  
Secondary Response ◽  
Fetal Sheep ◽  
Compression Phase ◽  
Umbilical Blood ◽  
Group I ◽  
Umbilical Blood Flow

We characterized the detailed hemodynamics of fetal blood pressure, heart rate, common umbilical blood flow, and femoral blood flow responses to partial compression of the umbilical cord and tested the hypothesis that repeated cord compression modulates fetal cardiovascular responses in 10 chronically instrumented fetal sheep at ∼130 days of gestation. In five fetuses ( group I), partial compression of the umbilical cord was induced 12 times, each for 5 min at 15-min intervals. Each cord compression reduced common umbilical blood flow by 50% and produced modest falls in fetal pH (7.33 ± 0 to 7.29 ± 0) and arterial [Formula: see text] (21.1 ± 0.2 to 16.8 ± 0.2 mmHg) and a mild increase in arterial[Formula: see text] (49.9 ± 0.5 to 54.9 ± 0.4 mmHg). Sham experiments were performed in five other fetuses ( group II). Second-by-second analysis of group I fetal cardiovascular data revealed a clear biphasic response to partial cord compression. Phase I (1st min of cord compression) was characterized by a rapid bradycardia and a rapid femoral vasoconstriction (primary response); phase II ( minutes 2–5of cord compression) was characterized by a delayed bradycardia and a return of femoral vascular resistance toward baseline (secondary response). Repeated cord compression abolished the primary, but not the secondary, cardiovascular responses. These results demonstrate that fetal cardiovascular responses to stress may be modified by preexposure to repeated intrauterine challenges.

Factors determining aortic and umbilical blood flow pulsatility in fetal sheep

1992 ◽  
Vol 18 (3) ◽  
pp. 255-266 ◽  
Author(s):  
S.L. Adamson ◽  
B.L. Langille
Keyword(s):  
Blood Flow ◽  
Fetal Sheep ◽  
Umbilical Blood ◽  
Flow Pulsatility ◽  
Umbilical Blood Flow

Absence of fetal placental waterfall phenomenon in chronically prepared fetal lambs

1976 ◽  
Vol 230 (4) ◽  
pp. 886-892 ◽  
Author(s):  
KL Thornburg ◽  
JM Bissonnette ◽  
JJ Faber
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Umbilical Vein ◽  
Venous Pressure ◽  
Amniotic Cavity ◽  
Umbilical Blood ◽  
Arterial Blood ◽  
Placental Blood ◽  
Umbilical Blood Flow

An electromagnetic flow sensor was placed on the distal fetal aorta (umbilical flow fraction 78.1 +/- 1.6 SEM, %), an inflatable occluder was tied around the umbilical cord, and catheters were placed in distal branches of an umbilical artery and vein, a uterine vein, and in the amniotic cavity. An inflatalbe occluder was tied around the vagina of some of the ewes. Control values 3 days after surgery were (mean +/- SE): fetal femoral artery pH, 7.37 +/- 0.01; umbilical blood flow, 186 +/- 14 ml-min-1 .kg fetus-1; fetal arterial blood pressure, 39 +/- 3 mmHg; and umbilical venous pressure, 7.4 +/- 1.0 mmHg (above intrauterine pressure). Fetal weight at autopsy was 3.1 +/- 0.3 kg, n = 11. Small increases in umbilical vein pressure caused immediate decreases in placental blood flow without decreases in fetal arterial blood pressure. The relation between venous pressure and umbilical blood flow at constant arterial pressure was that of an inert system, i.e., no evidence of a surrounding pressure (Starling resistor effect or waterfall phenomenon) could be found with increases in venous pressures of 2-40 mmHg. The results were not affected by increases in uterine vein pressure between 2 and 30 mmHg, nor by anesthesia and supine position of the ewe, nor by ganglionic blockade of the fetal ANS. It was concluded that surrounding pressures in the fetal placental circulation could not be demonstrated.

Placental transfer as a function of uterine blood flow

1982 ◽  
Vol 242 (3) ◽  
pp. H429-H436 ◽  
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.

scholarly journals CSH RNA Interference Reduces Global Nutrient Uptake and Umbilical Blood Flow Resulting in Intrauterine Growth Restriction

2021 ◽  
Vol 22 (15) ◽  
pp. 8150
Author(s):  
Amelia R. Tanner ◽  
Cameron S. Lynch ◽  
Victoria C. Kennedy ◽  
Asghar Ali ◽  
Quinton A. Winger ◽  
...  
Keyword(s):  
Blood Flow ◽  
Rna Interference ◽  
Nutrient Uptake ◽  
Intrauterine Growth Restriction ◽  
Growth Restriction ◽  
Intrauterine Growth ◽  
Umbilical Blood ◽  
Uterine Growth ◽  
Umbilical Blood Flow ◽  
Placental Hormone

Deficiency of the placental hormone chorionic somatomammotropin (CSH) can lead to the development of intrauterine growth restriction (IUGR). To gain insight into the physiological consequences of CSH RNA interference (RNAi), the trophectoderm of hatched blastocysts (nine days of gestational age; dGA) was infected with a lentivirus expressing either a scrambled control or CSH-specific shRNA, prior to transfer into synchronized recipient sheep. At 90 dGA, umbilical hemodynamics and fetal measurements were assessed by Doppler ultrasonography. At 120 dGA, pregnancies were fitted with vascular catheters to undergo steady-state metabolic studies with the 3H2O transplacental diffusion technique at 130 dGA. Nutrient uptake rates were determined and tissues were subsequently harvested at necropsy. CSH RNAi reduced (p ≤ 0.05) both fetal and uterine weights as well as umbilical blood flow (mL/min). This ultimately resulted in reduced (p ≤ 0.01) umbilical IGF1 concentrations, as well as reduced umbilical nutrient uptakes (p ≤ 0.05) in CSH RNAi pregnancies. CSH RNAi also reduced (p ≤ 0.05) uterine nutrient uptakes as well as uteroplacental glucose utilization. These data suggest that CSH is necessary to facilitate adequate blood flow for the uptake of oxygen, oxidative substrates, and hormones essential to support fetal and uterine growth.

The effect of steroids on the fetal brain and umbilical blood flow and biophysical profile

2003 ◽  
Vol 189 (6) ◽  
pp. S218
Author(s):  
Zeev Weiner ◽  
Rula Hamisa ◽  
Allan Fisher ◽  
Allan Bombard ◽  
Eliezer Shalev
Keyword(s):  
Blood Flow ◽  
Fetal Brain ◽  
Umbilical Blood ◽  
Biophysical Profile ◽  
Umbilical Blood Flow
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