Circulation During Pregnancy

Burwell, Cathy; Strayhorn, W. David; Flickinger, Don; Corlette, Marvin B.; Bowerman, Earl P.; Kennedy, J. A.

doi:10.1001/archinte.1938.00180170079007

Cited by 115 publications

(16 citation statements)

References 23 publications

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“…There is a consistent difference between the nitrous oxide concentrations of the umbilical arterial and umbilical venous blood of the infant removed at the end of periods of nitrous oxide administration up to one hour in duration. Furthermore, although, as we have reported, (6) the solubility of nitrous oxide is identical in blood, myometrium and a homogenate of all fetal tissues,s even after one hour am- 6 The solubility of nitrous oxide in amniotic fluid and in homogenates of whole fetus and myometrium was 16 18 This blood has circulated through the fetal body and is now returning to the placenta. This assumption is supported by experiments in animals, in which the fetal nitrous oxide content is directly determined and compared with the nitrous oxide concentration of umbilical arterial blood; 7 2.…”

Section: Methodsmentioning

confidence: 65%

Estimation of Uterine Blood Flow in Normal Human Pregnancy at Term 1

Metcalfe¹,

Romney²,

Ramsey³

et al. 1955

J. Clin. Invest.

Self Cite

182

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The blood flow to the pregnant uterus is of evident importance in supplying to the fetus the raw materials required for its growth and development and in removing from the fetal environment the waste products of metabolism. Description of the uterine blood supply was largely in anatomical terms until Barcroft and co-workers measured it directly in the rabbit (1), and indirectly in the sheep (2). It has also been calculated in the sheep (3, 4) from data obtained by fetal plethysmography (5). METHODS I. TheoryEstimation of human uterine blood flow at term has awaited the development of methods other than those used in animals. Recently, attempts (6, 7) have been made to apply the Fick principle (8) to the study of the maternal uterine circulation. Figure 1 presents this principle. It is modified from a derivation published by Kety (9) in a discussion of cerebral blood flow. This equation is applicable to any organ if (a) the amount of some blood-borne substance X taken up (or released) in a known time interval by that organ can be determined and if (b) the concentrations of substance X in blood entering and blood leaving the organ can be determined over the same period of time.The most familiar application of the Fick equation is in the determination of cardiac output. Here, since the blood flow to all body tissues is being studied, the oxygen consumption of the body may be used as the numerator of the equation and the difference in oxygen content between arterial and "mixed" venous blood is used as the denominator. The ideal test substance for use in the study of an individual organ is a blood-borne metabolite, the rate of production or destruction of which by that organ is measurable and the concentration of which in blood going to that organ and in mixed venous blood leaving that organ can be determined. As an example, hepatic blood flow has been calculated from knowledge of (a) the difference in concentrations of urea in blood entering and blood leaving the liver and (b) the rate of formation of urea, a process limited to the liver (10).Kety (9) has used a foreign substance, nitrous oxide gas, for determination of cerebral blood flow by the Fick principle. This substance is normally not present in the body and is not metabolized in body tissues. The method can be applied to the uterus if the amount of nitrous oxide in the uterus at the end of the experiment can be determined and if the concentrations of nitrous oxide in arterial blood supplying and venous blood draining the uterus during the experiment can be measured. For such an application the equation derived above ( Figure 1) would be modified to the following:Uterine Blood Flow N20 in uterus (N20) artery -(N20) uterine vein (Equation 1) The numerator consists of the total nitrous oxide content of the uterus and its contents at the end of the period of nitrous oxide inhalation. The denominator is the integrated arteriovenous nitrous oxide difference during the period of nitrous oxide inhalation. II. ProcedureObservations leading to an estimation of uteri...

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Section: Methodsmentioning

confidence: 65%

Estimation of Uterine Blood Flow in Normal Human Pregnancy at Term 1

Metcalfe¹,

Romney²,

Ramsey³

et al. 1955

J. Clin. Invest.

Self Cite

182

View full text Add to dashboard Cite

show abstract

“…In Groups I and V, the right ventricular end diastolic pressure was not above the upper utilized the foreign gas technique and performed serial studies in 4 patients throughout gestation (7). While the gas techniques have their recognized limitations (8), these serial studies illustrated an increased cardiac output with a fall toward normal prior to term.…”

Section: Pressuresmentioning

confidence: 99%

“…In addition to the welter of hormonal and body water changes, modifications in circulatory hemodynamics take place. Prior to the advent of cardiac catheterization, gas methods were utilized for the study of cardiac output in pregnant women (1)(2)(3)(4)(5)(6)(7). Data obtained in this manner indicated that the cardiac output increased during gestation.…”

mentioning

confidence: 99%

Hemodynamics at Rest and During Exercise in Normal Pregnancy as Studied by Cardiac Catheterization 12

Bader¹,

Bader²,

Rose³

et al. 1955

J. Clin. Invest.

245

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“…The return towards normal has begun before the onset of parturition. Burwell et al (1938) emphasized the similarity between the circulatory changes of pregnancy and those found in a patient with an arterio-venous shunt. They considered that in many ways the placenta resembled such a shunt.…”

Section: Discussionmentioning

confidence: 82%