O2 delivery to the pregnant uterus: its relationship to O2 consumption

1979 ◽  
Vol 237 (1) ◽  
pp. R52-R57
Author(s):  
D. Caton ◽  
C. Crenshaw ◽  
C. J. Wilcox ◽  
D. H. Barron
Keyword(s):  
Blood Flow ◽  
Relative Magnitude ◽  
O2 Consumption ◽  
Uterine Blood Flow ◽  
Pregnant Uterus ◽  
Content Difference ◽  
Several Variables ◽  
Pregnant Sheep ◽  
Systematic Relationships ◽  
O2 Delivery

Normal sheep were studied at intervals of 3-5 days during the last weeks of pregnancy in order to evaluate variability in rate of O2 consumption (QO2) of the uterus in relation to several variables involved in delivery of O2 to the organ. Among-animal differences of uterine QO2 were statistically significant and directly related to birthweight of the lamb. Among-animal differences of uterine blood flow (UBF) and uterine arteriovenous O2 content difference [C(a-v)O2] also were statistically significant, though neither was related to birthweight, presumably since they tended to vary inversely with one another. In a given ewe relative magnitude of UBF and of C(a-v)O2 was related to maternal arterial O2 content (CaO2), day of pregnancy, and whether the animal carried singlets or twins. Variability in QO2 was most closely related to UBF, although its relations to C(a-v)O2 and CaO2 were significant also. These data suggest there are systematic relationships among variables involved in the delivery of O2 to the uterus of pregnant sheep.

Regional blood flow and vascular resistance in response to oxytocin in the pregnant sheep and dog

1961 ◽  
Vol 16 (6) ◽  
pp. 1087-1092 ◽  
Author(s):  
N. S. Assali ◽  
L. Holm ◽  
H. Parker
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Regional Blood Flow ◽  
Uterine Blood Flow ◽  
Pregnant Uterus ◽  
Blood Flows ◽  
Uterine Contractions ◽  
Intravenous Drip ◽  
Pregnant Sheep ◽  
Regional Vascular Resistance

The effects of oxytocin on regional blood flow and regional vascular resistance were investigated in a group of pregnant ewes and bitches not in labor and in another group in early labor. Single injections or intravenous drip infusion did not change significantly arterial pressure, cardiac output, electrocardiogram, and renal, iliac, femoral, and carotid blood flows in any of the animals studied. The effects on the pregnant uterus were negligible before the onset of spontaneous labor. Only when the animal was in labor did oxytocin produce an increase in uterine contractions accompanied by a significant decrease in uterine blood flow. The data indicate that in the pregnant sheep and dog the circulatory action of oxytocin is limited to the pregnant uterus in labor and that the decrease in blood flow is probably due to an increase in intramural vascular resistance caused by the contracting myometrium around the uterine arterioles. Submitted on May 5, 1961

Uterine blood flow and oxygen consumption in pregnant sheep and goats

1959 ◽  
Vol 197 (4) ◽  
pp. 929-934 ◽  
Author(s):  
James Metcalfe ◽  
Seymour L. Romney ◽  
Joseph R. Swartwout ◽  
Donald M. Pitcairn ◽  
Anton N. Lethin ◽  
...  
Keyword(s):  
Blood Flow ◽  
Nitrous Oxide ◽  
Oxygen Consumption ◽  
Maternal Blood ◽  
Uterine Blood Flow ◽  
Human Beings ◽  
Pregnant Uterus ◽  
Fick Principle ◽  
Pregnant Sheep ◽  
Made In

This report deals with the volume of maternal blood flow to the pregnant uterus of the sheep and goat. Studies were made in 2 nonpregnant animals and in 20 pregnant animals at known stages of gestation. Measurements of uterine blood flow were made using nitrous oxide according to the Fick principle. The results indicate that in the nonpregnant uterus the blood flow is approximately 25 ml/min. It increases to approximately 200 ml/min. at the 80th day of gestation and exceeds 1000 ml/min. near the end of the 150-day gestation period of these animals. Data are also included for calculation of uterine O2 consumption. The findings with regard to uterine blood flow and O2 consumption are discussed in relation to previous findings in human beings and in rabbits.

Behavioral activity during prolonged hypoxemia in fetal sheep

1988 ◽  
Vol 65 (6) ◽  
pp. 2420-2426 ◽  
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.

Gastrointestinal blood flow and oxygen consumption in awake newborn piglets: effect of feeding

1983 ◽  
Vol 245 (5) ◽  
pp. G697-G702 ◽  
Author(s):  
P. T. Nowicki ◽  
B. S. Stonestreet ◽  
N. B. Hansen ◽  
A. C. Yao ◽  
W. Oh
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
O2 Consumption ◽  
Gi Tract ◽  
Local Blood Flow ◽  
O2 Uptake ◽  
O2 Extraction ◽  
Gastrointestinal Blood Flow ◽  
O2 Delivery ◽  
Effect Of Feeding

Regional and total gastrointestinal (GI) blood flow, O2 delivery, and whole-gut O2 extraction and O2 consumption were measured before and 30, 60, and 120 min after feeding in nonanesthetized, awake 2-day-old piglets. Cardiac output and blood flow to kidneys, heart, brain, and liver were also determined. Blood flow was measured using the radiolabeled microsphere technique. In the preprandial condition, total GI blood flow was 106 +/- 9 ml X min-1 X 100 g-1, while O2 extraction was 17.2 +/- 0.9% and O2 consumption was 1.99 +/- 0.19 ml O2 X min-1 X 100 g-1. Thirty minutes after slow gavage feeding with 30 ml/kg artificial pig milk, O2 delivery to the GI tract and O2 extraction rose significantly (P less than 0.05) by 35 +/- 2 and 33 +/- 2%, respectively. The increase in O2 delivery was effected by a significant increase in GI blood flow, which was localized to the mucosal-submucosal layer of the small intestine. O2 uptake by the GI tract increased 72 +/- 4% 30 min after feeding. Cardiac output and blood flow to non-GI organs did not change significantly with feeding, whereas arterial hepatic blood flow decreased significantly 60 and 120 min after feeding. The piglet GI tract thus meets the oxidative demands of digestion and absorption by increasing local blood flow and tissue O2 extraction.

Right and left ventricular O2 uptake during hemodilution and beta-adrenergic stimulation

1993 ◽  
Vol 265 (5) ◽  
pp. H1769-H1777 ◽  
Author(s):  
G. J. Crystal ◽  
S. J. Kim ◽  
M. R. Salem
Keyword(s):  
Blood Flow ◽  
Blood Cells ◽  
Left Ventricular ◽  
Adrenergic Stimulation ◽  
O2 Uptake ◽  
Isovolemic Hemodilution ◽  
Content Difference ◽  
O2 Extraction ◽  
In Series ◽  
O2 Delivery

Myocardial O2 uptake (MVO2) and related variables were compared in right and left ventricles (RV and LV, respectively) during isovolemic hemodilution (HD) alone and combined with isoproterenol (Iso) infusion in 13 isoflurane-anesthetized open-chest dogs. Measurements of myocardial blood flow (MBF) obtained with radioactive microspheres were used to calculate MVO2. Lactate extraction (Lacext) was determined. The study consisted of two experimental series: 1) graded HD (dextran) to hematocrit (Hct) of 10% and 2) Iso (0.1 microgram.kg-1.min-1 iv) during moderate HD (Hct = 18 +/- 1%). In series 1, arteriovenous O2 content difference in both ventricles decreased in parallel with reduced arterial O2 content caused by HD, i.e., percent O2 extraction was constant; MVO2 was maintained by proportional increases in MBF. In series 2, Iso during moderate HD raised MVO2 (RV, +156%; LV, +80%). Higher MVO2 was satisfied by combination of increased MBF and O2 extraction in RV and by increased MBF alone in LV. Lacext remained consistent with adequate myocardial O2 delivery throughout study. Conclusions were that 1) both RV and LV tolerated extreme HD (Hct = 10%) because blood flow reserves were sufficient to fully compensate for reduced arterial O2 content; 2) significant cardiac reserve was evident during HD, which could be recruited Iso; and 3) because increase in MVO2 in RV caused by Iso in presence of HD was partially satisfied by increased O2 extraction, the absence of augmented O2 extraction during HD alone was not due to impaired release of O2 from diluted red blood cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal oxygen uptake, oxygenation, and acid-base balance as a function of uterine blood flow

1983 ◽  
Vol 244 (6) ◽  
pp. H749-H755 ◽  
Author(s):  
R. B. Wilkening ◽  
G. Meschia
Keyword(s):  
Blood Flow ◽  
Base Excess ◽  
Umbilical Vein ◽  
Delivery Rate ◽  
Uterine Blood Flow ◽  
O2 Uptake ◽  
Acid Base Balance ◽  
Venous Pco2 ◽  
Base Balance ◽  
O2 Delivery

The rate of O2 delivery to the pregnant uterus (FaO2) was decreased in chronic sheep preparations by mechanical occlusion of uterine blood flow. The relationship of uterine venous O2 saturation (SVO2) to FaO2 was curvilinear with convexity toward the SVO2 axis. As SVO2 decreased, there was a decrease in uterine and umbilical venous O2 tension (PO2), with no appreciable reduction of the PO2 difference between the two veins and a decrease in the umbilical vein O2 delivery rate. Fetal O2 uptake and base excess remained normal as the umbilical vein O2 delivery rate was reduced from 1.1 to 0.6 mmol . min-1 . kg-1 but decreased markedly at an O2 delivery rate less than 0.5. Umbilical venous CO2 tension (PCO2) was higher than, and strongly correlated with, uterine venous PCO2 (R = 0.954). These observations support a venous equilibration model of ovine placental exchange and demonstrate that under normal physiological conditions the O2 supply to the fetal lamb is approximately twice the value necessary to maintain an adequate fetal O2 uptake and a normal fetal base excess.

scholarly journals Role of convective O2 delivery in determiningV˙o 2 on-kinetics in canine muscle contracting at peak V˙o 2

2000 ◽  
Vol 89 (4) ◽  
pp. 1293-1301 ◽  
Author(s):  
Bruno Grassi ◽  
Michael C. Hogan ◽  
Kevin M. Kelley ◽  
William G. Aschenbach ◽  
Jason J. Hamann ◽  
...  
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Muscle Fatigue ◽  
Oxidative Metabolism ◽  
Muscle Blood Flow ◽  
Content Difference ◽  
O2 Delivery ◽  
Gastrocnemius Muscles

A previous study (Grassi B, Gladden LB, Samaja M, Stary CM, and Hogan MC, J Appl Physiol 85: 1394–1403, 1998) showed that convective O2 delivery to muscle did not limit O2 uptake (V˙o 2) on-kinetics during transitions from rest to contractions at ∼60% of peakV˙o 2. The present study aimed to determine whether this finding is also true for transitions involving contractions of higher metabolic intensities.V˙o 2 on-kinetics were determined in isolated canine gastrocnemius muscles in situ ( n = 5) during transitions from rest to 4 min of electrically stimulated isometric tetanic contractions corresponding to the muscle peakV˙o 2. Two conditions were compared: 1) spontaneous adjustment of muscle blood flow (Q˙) (Control) and 2) pump-perfused Q˙, adjusted ∼15–30 s before contractions at a constant level corresponding to the steady-state value during contractions in Control (Fast O2 Delivery). In Fast O2 Delivery, adenosine was infused intra-arterially. Q˙ was measured continuously in the popliteal vein; arterial and popliteal venous O2 contents were measured at rest and at 5- to 7-s intervals during the transition. Muscle V˙o 2 was determined as Q˙times the arteriovenous blood O2 content difference. The time to reach 63% of the V˙o 2 difference between resting baseline and steady-state values during contractions was 24.9 ± 1.6 (SE) s in Control and 18.5 ± 1.8 s in Fast O2 Delivery ( P < 0.05). FasterV˙o 2 on-kinetics in Fast O2Delivery was associated with an ∼30% reduction in the calculated O2 deficit and with less muscle fatigue. During transitions involving contractions at peak V˙o 2, convective O2 delivery to muscle, together with an inertia of oxidative metabolism, contributes in determining theV˙o 2 on-kinetics.

The Effects of S(+)-Ketamine and Racemic Ketamine on Uterine Blood Flow in Chronically Instrumented Pregnant Sheep

2004 ◽  
pp. 497-502 ◽  
Author(s):  
Danja Str??mper ◽  
Wiebke Gogarten ◽  
Marcel E. Durieux ◽  
Kristian Hartleb ◽  
Hugo Van Aken ◽  
...  
Keyword(s):  
Blood Flow ◽  
Uterine Blood Flow ◽  
Pregnant Sheep ◽  
Racemic Ketamine

Effects of hyperthermia on uterine blood flow and shunting through uterine arteriovenous anastomoses in the late-pregnant ewe

1999 ◽  
Vol 11 (5) ◽  
pp. 201 ◽  
Author(s):  
Suzanne L. Miller ◽  
Graham Jenkin ◽  
David W. Walker
Keyword(s):  
Blood Flow ◽  
Experimental Period ◽  
Respiratory Alkalosis ◽  
Uterine Horn ◽  
Arteriovenous Anastomoses ◽  
Uterine Blood Flow ◽  
Ambient Conditions ◽  
Total Blood ◽  
Uterine Arteries ◽  
Pregnant Sheep

The effect of maternal hyperthermia on uterine blood flow (UBF) through the two main uterine arteries and on the proportion of UBF shunted through uterine arteriovenous anastomoses (AVAs) was investigated. Eight late-pregnant ewes were exposed to normothermic (22–23˚C) or hyperthermic (approx-imately 39˚C) ambient conditions for 8 h. UBF was measured in the left and right uterine arteries using flow probes and microspheres were injected into the uterine artery before, during and after the experimental period. The distribution of microspheres between the uterus and lungs was determined to calculate changes in capillary and AVA blood flows. Hyperthermia produced a significant (P<0.05) increase in maternal core temperature (+1.5˚C), increase in maternal blood pH (+0.21; P<0.05) and decrease in maternal pCO 2 (–16.2 mmHg; P<0.05). Blood flow to the uterine horn ipsilateral to the corpus luteum (CL) remained unchanged during hyperthermia, whereas total UBF and blood flow to the contralateral uterine horn were significantly decreased (P<0.05), by 23.1% and 20.8%, respectively, of pre-heat control values. The proportion of UBF shunted through uterine AVAs during hyperthermia was not significantly different from values observed in normothermic ewes (21.9 0.7%). Mild to moderate hyperthermia in late-pregnant sheep induces respiratory alkalosis and decreases total blood flow to the uterus, brought about by a decrease in blood flow to the uterine horn contralateral, but not ipsilateral to the CL. Heat treatment does not alter the proportion of UBF traversing uterine AVAs.

Oxygen, glucose, and lactate uptake by fetus and placenta during prolonged hypoxemia

1995 ◽  
Vol 268 (2) ◽  
pp. R303-R309 ◽  
Author(s):  
S. B. Hooper ◽  
D. W. Walker ◽  
R. Harding
Keyword(s):  
Blood Flow ◽  
Glucose Uptake ◽  
Lactate Clearance ◽  
Gravid Uterus ◽  
Uterine Blood Flow ◽  
Fetal Circulation ◽  
Umbilical Blood ◽  
Pregnant Sheep ◽  
Lactate Uptake ◽  
Arterial O2 Saturation

Our aim was to compare the effects of short (4 h) and prolonged (24 h) periods of reduced uterine blood flow (RUBF) on fetal and placental uptake of O2, glucose, and lactate. In pregnant sheep, uterine and umbilical blood flows were measured under normal conditions and after 4 and 24 h of RUBF. A 50% reduction in uterine blood flow caused a 56% reduction in fetal arterial O2 saturation (SaO2). Umbilical blood flow increased from 325 +/- 33 to 378 +/- 32 ml.min-1.kg-1 (P < 0.05) after 4 h but was not different from pre-RUBF values after 24 h. O2 uptake by the gravid uterus was not altered by RUBF, due to an increase (84%) in uterine O2 extraction. Similarly, uteroplacental and fetal O2 consumptions and fetal glucose uptake were not affected by RUBF, whereas uteroplacental glucose uptake was significantly reduced after 4 h (by 42%) and 24 h (by 58%) of RUBF. Fetal lactate uptake was greatly reduced from 78.7 +/- 15.5 to -167 +/- 57 mumol.min-1.kg-1 after 4 h and to -198 +/- 80 mumol.min-1.kg-1 after 24 h of RUBF; negative values indicate placental lactate uptake from the fetal circulation. Thus, although RUBF significantly reduced fetal SaO2, fetal and uteroplacental O2 consumptions did not change. In addition, although fetal glucose uptake was not altered by RUBF, during RUBF the placenta became a major site of lactate clearance from the fetal circulation.

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