L. Nylund

Uteroplacental Blood Flow in Pre-Eclampsia Measurements with Indium-113M and a Computer-Linked Gamma Camera

Uteroplacental blood flow was measured with a computer-linked gamma camera after intravenous injection of 1 mCi indium-113m. Results of the measurements from 32 pre-eclamptic pregnancies and 37 normal controls are compared. The uteroplacental blood flow was measured as an index calculated from the rise time and maximum activity of the isotope accumulation curve. The uteroplacental blood flow was reduced with 50% in pre-eclampsia. In severe pre-eclampsia it was more compromised than in mild pre-eclampsia. A diminished uteroplacental blood flow was found in pre-eclampsia even in the absence of intrauterine growth retardation. The maternal placental circulation in the supine position was reduced with one third compared to that in the left lateral recumbent position.

Uteroplacental blood flow in diabetic pregnancy: Measurements with indium 113m and a computer-linked gamma camera

The uteroplacental blood flow index in the last trimester of pregnancy in 26 women with diabetes mellitus was compared to that in 41 healthy control subjects. After an intravenous injection of 1 mCi of indium 113m, the radiation over the placenta was recorded with a computer-linked gamma camera. From time-activity analysis of the isotope accumulation curve, a uteroplacental blood flow index could be calculated. In the diabetic pregnant women, the maternal-placental blood flow index was reduced 35% to 45% compared to that in healthy women. The blood flow index tended to be further impaired in those diabetic women who had higher blood glucose values.

Uteroplacental blood flow index in intrauterine growth retardation of fetal or maternal origin

Summary. Uteroplacental blood flow index was determined in 30 women with intrauterine growth retardation (IUGR group) and in 26 women without fetal growth retardation (control group) during the last trimester of pregnancy. After 1 mCi (37 MBq) of indium‐113m chloride had been injected intravenously the radiation was registered by a computer‐linked scintillation camera positioned above the placenta during 10 s‐intervals for 240 s. From the isotope accumulation curve a Uteroplacental blood flow index could be calculated for each patient. The median blood flow index in the IUGR group was less than half of that in the control group. In the IUGR group the index was as low in the six women who gave birth to infants with congenital malformations as in the other 24 women in whom fetal growth retardation was due to maternal factors.

Comparison of Uteroplacental Blood Flow in Normal and in Intrauterine Growth-Retarded Pregnancy

Uteroplacental blood flow was studied with a noninvasive method using indium-113m and a computer-linked gammacamera. The blood flow was determined from the ratio of the maximum and the rise time of the isotope accumulation curve of the placenta. Eight pregnancies with intrauterine growth retardation (IUGR) were compared with 11 normal pregnancies. In the IUGR group the mean placental blood flow was only 1/4 of corresponding mean values of the normal group. The difference was highly significant (p less than 0.01).

Acute effect of an antihypertensive drug, labetalol, on uteroplacental blood flow

Summary. The effect of a new antihypertensive drug, labetalol, on uteroplacental blood flow was determined in eight pre‐eclamptic women. After injection of 0.5 mCi of 113mIn the radioactivity in the placenta was recorded by a gamma camera linked to a computer and the placental blood‐flow index was calculated from the ratio between the maximum radioactivity of the isotope‐accumulation curve and the rise time of the curve. Labetalol, a combined α‐ and β‐adrenoceptor antagonist was given intravenously and after 30 min a second uteroplacental blood‐flow index was calculated. There was a significant mean decrease of blood pressure from 147/98 to 128/83 mmHg, but no change in uteroplacental blood‐flow index, so that uteroplacental vascular resistance tended to decrease.

Fetal scalp catecholamines during labor

Samples of scalp blood were collected from 129 fetuses during the first stage of labor for analysis of plasma norepinephrine and epinephrine concentrations by high-performance liquid chromatography. The catecholamine levels were related to scalp blood pH and fetal heart rate patterns during the 20-minute period preceding the collection of scalp blood. The median norepinephrine level was 9.2 nmol/L (range, 1.3 to 99.7), and the median epinephrine level was 0.5 nmol/L (range, less than 0.5 to 19.2) (n = 111) during the first stage of labor when the pH was above 7.25. The norepinephrine level was considerably higher than that in the resting adult. Significantly higher concentrations of catecholamines were found when scalp blood pH was below 7.26 (p less than 0.001). Maternal analgesia did not influence the fetal catecholamine levels in uncomplicated labor. Significantly higher concentrations of norepinephrine were found during the appearance of abnormal fetal heart rate patterns.

Acute Effect of Dihydralazine on Uteroplacental Blood Flow in Hypertension during Pregnancy

The uteroplacental blood flow was measured in 12 women with hypertension during pregnancy before and after intravenous injection of dihydralazine. After intravenous administration of 18.5 MBq (0.5 mCi) 113mIn, the gamma radiation emanating from the placenta was recorded with a computer-linked gamma camera during 10-second intervals for 240 s. From time-activity analysis of the isotope curve a uteroplacental blood flow index could be calculated. 30 min after the intravenous injection of dihydralazine, 18.5 MBq 113mIn were again administered, and a second uteroplacental blood flow index was calculated. After dihydralazine administration there was a significant reduction of mean blood pressure (p less than 0.01) and an increase of mean maternal heart rate (p less than 0.01). There was no significant change in uteroplacental blood flow or in uteroplacental vascular resistance.

Labetalol for the Treatment of Hypertension in Pregnancy: Pharmakokinetics and effects on the uteroplacental blood flow

Abstract. Plasma levels of labetalol were measured in 7 hypertensive pregnant women who were given 200 mg three times daily orally. The plasma concentrations were usually lower than those reported in the non‐pregnant state at a comparative dose. In 5 women the ratio between fetal and maternal plasma labetalol concentrations could be calculated at parturition. The median value of this quotient was about 50%. The effect of labetalol 1 mg/kg body weight intravenously was registered with functional placental scintigraphy. Fifteen women participated. A computer‐linked gamma camera above the uterus registered the radioactivity in the placental region after two intravenous bolus injections of 18.5 MBq indium‐113m chloride. From the radioactivity uptake curves, uteroplacental blood flow indices could be calculated before and 30 minutes after the labetalol injection. Despite a significant reduction in maternal blood pressure, no change in uteroplacental blood flow index was found. This could indicate that the vascular resistance in the maternal placental circulation was reduced by labetalol.

Acute volume expansion in normal pregnancy and preeclampsia: Effects on plasma atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP) concentrations and feto-maternal circulation

Objective. To compare normal pregnancy with pregnancy‐induced hypertension (PIH)/preec‐lampsia with respect to the effects of acute volume expansion on plasma atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP) and fetal‐maternal circulation. Design. Observational study.

Uteroplacental blood flow measured by placental scintigraphy during epidural anaesthesia for caesarean section

The uteroplacental blood flow was measured before and during epidural anaesthesia for caesarean section in 11 women. The blood flow was measured with dynamic placental scintigraphy. After an i.v. injection of indium‐113m chloride, the gamma radiation over the placenta was recorded with a computer‐linked scintillation camera. The uteroplacental blood flow could be calculated from the isotope accumulation curve. The anaesthesia was performed with bupivacaine plain 0.5%, 18–22 ml and a preload of a balanced electrolyte solution 10 ml/kg b.w. was given. The placental blood flow decreased in eight patients and increased in three with a median change of – 21%, not being statistically significant. No correlation between maternal blood pressure and placental blood flow was found.