Fetal Umbilical Venous Research Articles

Association of free maternal and fetal ropivacaine after epidural analgesia for intrapartum caesarean delivery: a prospective observational trial

BackgroundRopivacaine is present in plasma in both protein-bound and free forms. The free form is responsible for the occurrence of toxic side effects. During obstetric epidural analgesia, free ropivacaine enters the fetal circulation depending on various factors. The aim of this study was to analyse a potential association between ropivacaine concentrations in maternal and fetal plasma and hence the extent of fetal exposure to ropivacaine. MethodsIn this prospective monocentre study, parturients who met the following criteria were included in the study: 1. epidural administration as part of obstetric anaesthesia, and 2. subsequent intrapartum caesarean delivery, which 3. was performed after an epidural bolus administration of ropivacaine within the existing epidural analgesia. Total and free ropivacaine concentrations were analysed in maternal blood at baseline, prior to epidural bolus administration for caesarean delivery, and in maternal and fetal (umbilical venous, oxygenated) blood at delivery. The results are presented as mean ± SD or median (25/75th percentile). ResultsWe screened 128 parturients who went into labour at term and requested epidural analgesia, of whom 39 were ultimately included in the study. An intrapartum caesarean delivery was performed after the epidural application of 207 (166/276) mg ropivacaine during an epidural treatment period of 577 (360/1010) min. Total and free ropivacaine concentrations were 1402 ± 357 ng/ml and 53 ± 46 ng/ml, respectively, in maternal venous blood and 457 ± 243 ng/ml and 43 ± 27 ng/ml, respectively, in fetal blood. The maternal total and free ropivacaine concentrations were significantly correlated (r = 0.873; P < 0.0001). ConclusionThe results of the present study suggest that determining the concentration of free ropivacaine in maternal blood may be a feasible option for estimating neonatal exposure to ropivacaine.

Successful Prediction of Fetal Exposure to Dual BCRP/P-gp Drug Substrates Using the Efflux Ratio-Relative Expression Factor Approach and PBPK M&S.

To inform fetal drug safety, it is important to determine or predict fetal drug exposure throughout pregnancy. The former is not possible in the first or second trimester. In contrast, at the time of birth, fetal drug exposure, relative to maternal exposure, can be estimated as Kp,uu (unbound fetal umbilical venous (UV) plasma area under the curve (AUC)/unbound maternal plasma (MP) AUC), provided the observed UV/MP values, spanning the dosing interval, are available from multiple maternal-fetal dyads. However, this fetal Kp,uu cannot be extrapolated to other drugs. To overcome the above limitations, we have used an efflux ratio-relative expression factor (ER-REF) approach to successfully predict the fetal Kp,uu of P-gp substrates. Because many drugs taken by pregnant people are also BCRP substrates, here, we extend this approach to drugs that are effluxed by both placental BCRP and P-gp or P-gp alone. To verify our predictions, we chose drugs for which UV/MP data were available at term: glyburide and imatinib (both BCRP and P-gp substrates) and nelfinavir (only P-gp substrate). First, the ER of the drugs was determined using Transwells and MDCKII cells expressing either BCRP or P-gp. Then, the ER was scaled using the proteomics-informed REF value to predict the fetal Kp,uu of the drug at term. The ER-REF predicted fetal Kp,uu of glyburide (0.43), imatinib (0.42), and nelfinavir (0.40) fell within two-fold of the corresponding in vivo fetal Kp,uu (0.44, 0.37, and 0.46, respectively). These data confirm that the ER-REF approach can successfully predict fetal drug exposure to BCRP/P-gp and P-gp substrates, at term.

Effect of spontaneous breathing on umbilical venous blood flow and placental transfusion during delayed cord clamping in preterm lambs

IntroductionDuring delayed umbilical cord clamping, the factors underpinning placental transfusion remain unknown. We hypothesised that reductions in thoracic pressure during inspiration would enhance placental transfusion in spontaneously breathing preterm lambs.ObjectiveInvestigate...

Case 253: Thrombosed Umbilical Venous Varix in an Infant

History A 3-month-old previously healthy girl presented to an outside institution with a 4-day history of low-grade fever, irritability, and a tender "knot" in the upper abdomen. Ultrasonography (US) was performed at an outside hospital. US images were not available for review; however, they showed a mass in the left hepatic lobe, per the outside report, and the patient was referred to our institution for further evaluation. Her parents reported a normal full-term pregnancy, with regular prenatal care and normal prenatal US findings. The baby was born after an uncomplicated gestation. She was delivered at term via an uncomplicated cesarean section due to a maternal history of cesarean section. The perinatal course was uncomplicated, and there was no history of umbilical catheterization, per the parents. On arrival at our institution, the patient had a temperature of 38.2°C. All other vital signs were normal. Palpation revealed a tender and firm mass in the periumbilical region; otherwise, physical examination findings were normal. Results of laboratory work-up were normal, except for elevated white blood cell count (26 600/mm3 [26.6 × 109/L]; normal, 6000-17 500/mm3 [6-17.5 × 109/L]). The patient underwent US followed by intravenous contrast material-enhanced (10 mL ioversol, Optiray 320; Medtronic, Santa Rosa, Calif) computed tomography (CT) on the same day.

Propofol in combination with remifentanil for cesarean section: Placental transfer and effect on mothers and newborns at different induction to delivery intervals

ObjectiveThis study aims to describe the administration of propofol in combination with remifentanil for the induction of general anesthesia during cesarean section (CS). Our aim was to evaluate its impact on the drug concentrations of the maternal and neonatal blood at different induction of anesthesia to delivery (I–D) intervals as well as its effect on newborns. Materials and methodsIn this double-blind randomized controlled study, patients undergoing elective CS were administered anesthesia at short (n = 20) or long (n = 20) I–D intervals. Anesthesia was induced with 1 mg/kg propofol and 1 μg/kg remifentanil and maintained by continuous infusion of 3 mg/kg/h propofol and 7 μg/kg/h remifentanil. ResultsThe mean plasma propofol concentrations at delivery in the maternal arterial (MA) blood and the fetal umbilical arterial (UA) and venous (UV) blood in the short I–D interval group were 1.91, 1.17, and 0.51 μg/mL, respectively, while those in the long I–D interval group were 1.57, 1.07, and 0.61 μg/mL, respectively. The mean plasma remifentanil concentrations at delivery in the MA, UA, and UV in the short I–D interval group were 2.25, 1.43, and 0.65 ng/mL, respectively, and those in the long I–D interval group were 1.96, 1.25, and 0.75 ng/mL, respectively. There were no statistically significant differences in the neonatal Apgar scores and neurological adaptive capacity scores between the two groups. ConclusionsIt is safe to administer propofol in combination with remifentanil by continuous infusion after the bolus dose for the induction of anesthesia during cesarean section. Prolonging the I–D interval within a certain limit will not have any significant influence on the fetus.

P37. Alterations in maternal and fetal plasma soluble endothelial leukocyte adhesion molecule-1 (sE-selectin) concentrations in women with pre-eclampsia

Introduction Pre-eclampsia (PE) is an important cause of perinatal and maternal morbidity, especially when diagnosed at or before 34 weeks’ gestation (early-onset PE), and is characterised by endothelial dysfunction/inflammation. E-selectin belongs to the selectin family of adhesion molecules involved in guiding non-activated polymorphonuclear cells to areas of inflammation in the endothelial layer. sE-selectin is a sensitive and specific marker of endothelial dysfunction, thus may be important in PE. Objective To determine whether plasma sE-selectin concentrations differed between normotensive controls (NC) and PE, as well as sub-grouped in early- and late-onset (>34 weeks’ gestation) PE in matched maternal and fetal samples. Methods sE-selectin was measured by ELISA in maternal and fetal umbilical venous EDTA plasma from NC ( n = 17) or pre-eclamptic ( n = 17) pregnancy. Distribution-free statistical tests were used. Results In PE overall, maternal sE-selectin concentrations were raised compared to normotensive controls (median [IQR]: 7.6 [6.9, 8.5] vs. 5.0 [3.5, 8.2] ng/ml; P vs. 10.6 [7.9, 15.1] ng/ml; P P n = 5) and late-onset PE ( n = 12), only the early-onset had higher maternal sE-selectin ( P Conclusions The increased maternal plasma sE-selectin in pre-eclampsia reflects the endothelial dysfunction, possible due to oxidative stress, which is apparent only in the more severe early-onset PE. The lower levels in the fetal plasma and the lack of difference between maternal and fetal circulations from the pre-eclampsia suggest there may be a different regulatory mechanism in the fetus.

Diabetes and hypertension increase the placental and transcellular permeation of the lipophilic drug diazepam in pregnant women

BackgroundPrevious studies carried out in our laboratories have demonstrated impaired drug permeation in diabetic animals. In this study the permeation of diazepam (after a single dose of 5 mg/day, administered intramuscularly) will be investigated in diabetic and hypertensive pregnant women.MethodsA total 75 pregnant women were divided into three groups: group 1 (healthy control, n = 31), group 2 (diabetic, n = 14) and group 3 (hypertensive, n = 30). Two sets of diazepam plasma concentrations were collected and measured (after the administration of the same dose of diazepam), before, during and after delivery. The first set of blood samples was taken from the mother (maternal venous plasma). The second set of samples was taken from the fetus (fetal umbilical venous and arterial plasma). In order to assess the effect of diabetes and hypertension on diazepam placental-permeation, the ratios of fetal to maternal blood concentrations were determined. Differences were considered statistically significant if p ≤ 0.05.ResultsThe diabetes and hypertension groups have 2-fold increase in the fetal umbilical-venous concentrations, compared to the maternal venous concentrations. Feto: maternal plasma-concentrations ratios were higher in diabetes (2.01 ± 1.10) and hypertension (2.26 ± 1.23) groups compared with control (1.30 ± 0.48) while, there was no difference in ratios between the diabetes and hypertension groups. Umbilical-cord arterial: venous ratios (within each group) were similar among all groups (control: 0.97 ± 0.32; hypertension: 1.08 ± 0.60 and diabetes: 1.02 ± 0.77).ConclusionsOn line with our previous findings which demonstrate disturbed transcellular trafficking of lipophilic drugs in diabetes, this study shows significant increase in diazepam placental-permeation in diabetic and hypertensive pregnant women suggesting poor transcellular control of drug permeation and flux, and bigger exposure of the fetus to drug-placental transport.

Homocysteine and folate plasma concentrations in mother and baby at delivery after pre-eclamptic or normotensive pregnancy: Influence of parity

Pre-eclampsia affects between 2% and 7% of all pregnant women, contributing to perinatal and maternal morbidity. There are conflicting data on plasma homocysteine and folate in pre-eclampsia, and little about fetal concentrations. Objectives Firstly, to compare the concentrations of homocysteine and folate in maternal and paired fetal (umbilical venous) plasma samples from normotensive or pre-eclamptic pregnancies at delivery; secondly, to identify any effect of parity on these concentrations. Study design Hospital based cross-sectional study consisting of 24 normotensive and 16 pre-eclamptic pregnant White European women from whom maternal and fetal plasma samples were collected at delivery. Main outcome measures Maternal and fetal plasma homocysteine and folate concentrations between normotensive and pre-eclamptic pregnancies with varying parity. Results There were no significant differences in either maternal or fetal plasma homocysteine or folate concentrations between normotensive and pre-eclamptic pregnancies, or between homocysteine and folate. In both the normotensive and pre-eclamptic women, plasma folate concentration was higher in paired fetal compared to maternal plasma ( P < 0.001 and P = 0.047, respectively). With regards to homocysteine, only the normotensive samples had higher fetal concentrations ( P = 0.002). Both maternal and fetal plasma folate concentrations were lower in parous women ( P = 0.001 and P = 0.017, respectively), the lowest concentrations being in pre-eclamptic parous women ( P = 0.004), but homocysteine concentrations were similar ( P > 0.4 for both). Conclusions The low plasma folate in parous women is an interesting finding and, when intake is also low, may contribute to adverse pregnancy outcomes, particularly in relation to pre-eclampsia.

P16.12: Quantitative fetal umbilical venous volume flow between 11 and 14 weeks: a pilot study

Objective: Quantitative assessment of fetal venous volume flow can be used in compromised fetuses such as in intrauterine growth restriction. In a pilot study, we explored the feasibility of umbilical venous volume flow ultrasound measurements in fetuses at the time of NT measurement for individual chromosomal risk assessment. Methods: In 26 fetuses the NT was measured and the umbilical venous volume flow quantified non-invasively using ‘‘colour velocity imaging’’ (CVI) in the proximal straight portion of the intraabdominal umbilical vein. Results: All fetuses but four had NT values below the 95th centile (adjusted for crown rump length) of whom one with a mildly increased NT was found to have trisomy 21. All other pregnancies had a normal pregnancy outcome. Quantitative umbilical volume flow as measured by CVI ranged from 5 to 32 mL/min and increased between 11 and 14 weeks’ gestation in a linear fashion. Conclusions: Fetal umbilical volume flow can be measured noninvasively using colour velocity imaging. Umbilical venous volume flow increases between 11 and 14 weeks. One fetus with a mildly increased NT and trisomy 21 showed a normal umbilical volume flow.

Assessment of fetal liver volume and umbilical venous volume flow in pregnancies complicated by insulin‐dependent diabetes mellitus

To determine fetal liver volume and its relation with umbilical venous volume flow and maternal glycosylated haemoglobin (HbA1c) in pregnancies complicated by diabetes mellitus type I. A cross sectional matched control study. Obstetric out patient clinic, Erasmus MC-University Medical Centre, Rotterdam. Data from fetuses of diabetic women (n = 32; 18-36 weeks) were compared with data from normal controls (n = 32) matched for gestational age. Umbilical venous cross sectional area (mm(2)) and time-averaged velocity (mm/s Doppler) were determined for calculation of volume flow (mL/min) and flow per kilogram fetal weight (mL/min/kg). Umbilical artery pulsatility index was determined. Fetal liver volume measurements were obtained using a Voluson 530-D. Fetal liver volume, umbilical venous volume flow and downstream impedance. A statistically significant difference between fetuses of diabetic women and normal controls was found for liver volume (mean [SD]: 45.9 [34.0] vs 38.3 [28.7] mL), abdominal circumference (22.2 [6.6] vs 21.3 [5.6] cm), estimated fetal weight (1162 [898] vs 1049 [765] g) and fetoplacental weight ratio (0.22 vs 0.19) and liver volume/estimated fetal weight ratio (4.13% [0.007] vs 3.62% [0.009]). Umbilical venous volume flow (mL/min) and umbilical artery pulsatility index were not essentially different between the two study groups, but umbilical venous volume flow per kilogram fetal weight was lower (P < 0.05) in the diabetes group (94.3 [26.1] mL/min kg) compared with normal controls (109.5 [28.0] mL/min/kg). A positive correlation existed between fetal liver volume and maternal HbA1c (P = 0.002). Measurement of fetal liver volume by three-dimensional ultrasound may play a role in identifying fetal growth acceleration in diabetic pregnancies. Fetal liver volume increase is positively related to maternal HbA1c levels reflecting degree of maternal glycemic control. Fetal liver volume normalised for estimated fetal weight is significantly higher in the fetuses of diabetic women. In the present study, umbilical venous volume flow and fetoplacental downstream impedance are not different between diabetic and normal pregnancies.

Assessment of fetal liver volume and umbilical venous volume flow in pregnancies complicated by insulin-dependent diabetes mellitus

Objectives To determine fetal liver volume and its relation with umbilical venous volume flow and maternal glycosylated haemoglobin (HbA1c) in pregnancies complicated by diabetes mellitus type I. Design A cross sectional matched control study. Setting Obstetric out patient clinic, Erasmus MC—University Medical Centre, Rotterdam. Population Data from fetuses of diabetic women (n = 32; 18–36 weeks) were compared with data from normal controls (n = 32) matched for gestational age. Methods Umbilical venous cross sectional area (mm2) and time-averaged velocity (mm/s Doppler) were determined for calculation of volume flow (mL/min) and flow per kilogram fetal weight (mL/min/kg). Umbilical artery pulsatility index was determined. Fetal liver volume measurements were obtained using a Voluson 530-D. Main outcome measures Fetal liver volume, umbilical venous volume flow and downstream impedance. Results A statistically significant difference between fetuses of diabetic women and normal controls was found for liver volume (mean [SD]: 45.9 [34.0] vs 38.3 [28.7] mL), abdominal circumference (22.2 [6.6] vs 21.3 [5.6] cm), estimated fetal weight (1162 [898] vs 1049 [765] g) and fetoplacental weight ratio (0.22 vs 0.19) and liver volume/estimated fetal weight ratio (4.13% [0.007] vs 3.62% [0.009]). Umbilical venous volume flow (mL/min) and umbilical artery pulsatility index were not essentially different between the two study groups, but umbilical venous volume flow per kilogram fetal weight was lower (P < 0.05) in the diabetes group (94.3 [26.1] mL/min kg) compared with normal controls (109.5 [28.0] mL/min/kg). A positive correlation existed between fetal liver volume and maternal HbA1c (P = 0.002). Conclusions Measurement of fetal liver volume by three-dimensional ultrasound may play a role in identifying fetal growth acceleration in diabetic pregnancies. Fetal liver volume increase is positively related to maternal HbA1c levels reflecting degree of maternal glycemic control. Fetal liver volume normalised for estimated fetal weight is significantly higher in the fetuses of diabetic women. In the present study, umbilical venous volume flow and fetoplacental downstream impedance are not different between diabetic and normal pregnancies.

Steady-state maternal and fetal plasma concentrations of glyceryl trinitrate (GTN) in the preterm sheep.

The administration of glyceryl trinitrate (GTN; nitroglycerin) is increasing during preterm pregnancies, yet its disposition and, importantly, the extent of fetal exposure remain to be elucidated. When used as a tocolytic (pharmacological agent that stops uterine contractions), it is administered transdermally (24-48 h). Here, we quantified the maternal and fetal steady-state plasma concentrations of maternal intravenous GTN in preterm sheep and continuously monitored maternal and fetal vascular parameters to observe possible dose-dependent vascular effects. Preterm (120 days gestation) pregnant sheep (n = 6) were instrumented with maternal femoral arterial (MA) and venous (MV) and fetal femoral arterial (FA) and umbilical venous (UV) polyethylene blood-sampling catheters. During maternal GTN infusion (3.0 micro g.kg-1.min-1, 60-min duration) the steady-state GTN concentrations ([GTN]) were as follows: MA, 98.6 +/- 9.0 nM; UV, 17.4 +/- 7.6 nM; and FA, <5 nM. There were no changes in maternal and fetal mean arterial pressure and heart rate or in uterine activity. Overall, the steady-state [GTN] was established by 5 min, and the UV/MA ratio of [GTN] was 0.18. The FA [GTN] (<5 nM) indicates that the fetus cleared essentially all GTN in the UV, and the maternal and fetal heart rate and mean arterial pressure appear to be independent of maternal GTN infusion.

Fetal brain/liver volume ratio and umbilical volume flow parameters relative to normal and abnormal human development.

To estimate fetal brain volume from head circumference and published postmortem data; to determine normal values for the fetal brain/liver volume ratio relative to gestational age; to establish the relationship between the brain/liver volume ratio and fetal circulatory parameters during normal and restricted (SGA) fetal growth. This was a cross-sectional study involving a total of 47 uncomplicated pregnancies appropriate-for-gestational age (AGA) and 23 pregnancies resulting in the delivery of a SGA fetus. At enrollment gestational age ranged between 20 and 36 weeks in both groups. Umbilical venous cross-sectional area and time-averaged velocity for calculation of volume flow as well as velocity waveforms from the umbilical artery, middle cerebral artery and ductus venosus, were recorded. Fetal liver volume measurements were obtained using three-dimensional ultrasound. Fetal brain volume was estimated from fetal head volume following comparison with published postmortem data on fetal brain weight. A significant correlation was observed between prenatally estimated fetal head volume and postmortem fetal brain volume. Fetal brain volume was approximately half that of fetal head volume. The normal fetal brain/liver volume ratio demonstrated a significant reduction with gestational age (R = -0.54; P < 0.001). The normal mean +/- standard deviation (SD) fetal brain/liver volume ratio (3.4 +/- 0.7) was significantly different (P < 0.001) from the mean fetal brain/liver volume ratio in the SGA group (n = 23) (5.9 +/- 1.9). A significant difference existed for mean umbilical venous volume flow between AGA (104.7 +/- 26.9 mL/min/kg) and SGA (59.6 +/- 22.7 mL/min/kg) fetuses. In the SGA fetus, there was a significant inverse relationship (P < 0.001) between fetal weight-related umbilical venous volume flow and fetal brain/liver volume ratio. In a subset of 16 SGA and 16 AGA fetuses matched for gestational age, a significant difference existed for umbilical artery pulsatility index (2.30 +/- 1.52 vs. 0.99 +/- 0.19), fetal middle cerebral artery pulsatility index (1.3 +/- 0.4 vs. 2.1 +/- 0.3) and late diastolic flow velocity in the fetal ductus venosus (6.9 +/- 14.2 cm/s vs. 23.9 +/- 8.8 cm/s), but not for peak systolic, early diastolic and time-averaged velocity in the ductus venosus. Sonographic estimates of fetal brain volume can be obtained. The fetal brain/liver volume ratio is a predictor of fetal outcome in the growth-restricted fetus. An inverse relationship exists in SGA fetuses between brain/liver volume ratio and fetal weight-related umbilical venous blood flow.

OC132: Quantitative fetal umbilical venous volume flow: comparison of two methods, normal values and possible clinical applications

OC132: Quantitative fetal umbilical venous volume flow: comparison of two methods, normal values and possible clinical applications

Degree of fetal umbilical venous constriction at the abdominal wall in a low-risk population at 20-40 weeks of gestation.

To determine the degree of constriction of the umbilical vein at the abdominal wall in the second half of pregnancy. A total of 283 low-risk singleton pregnancies were recruited for a cross-sectional study, and examined once at 20-40 weeks of gestation. Two sets of ultrasound measurements of the umbilical vein were taken: one at the fetal end of the umbilical cord and another at the inlet through the abdominal wall, the umbilical ring. The diameter was determined as an average of >or=5 repeat measurements. The blood velocity was recorded at the same site. The time-averaged maximum venous blood velocity in the cord was low (mean 13-19 cm/s during 20-40 weeks of gestation), and the corresponding mean diameter 3.6-8.2 mm. In contrast, the mean of the venous blood velocity at the umbilical ring was 34-41 cm/s and the diameter was 2.8-5.9 mm during the same period. Of 191 pairs of observations, 41 (21%) had a velocity increment of >or=300 %, which corresponds to a diameter reduction to half or more at the umbilical ring. Constriction of the umbilical ring is a common phenomenon in the second half of pregnancy.

Association of severe placental insufficiency and systemic venous pressure rise in the fetus with increased neonatal cardiac troponin T levels

Objective: The aim of this study was to test the hypothesis that severe placental insufficiency and a rise in fetal systemic venous pressure are associated with fetal myocardial cell damage, which in turn leads to increased neonatal troponin T levels. Study Design: Sixty-six neonates born after uncomplicated pregnancy and delivery were included in the control group. Study groups 1 and 2 consisted of 32 and 5 neonates, respectively, born to women with hypertensive disorder. In study group 1 the fetal intra-abdominal portion of the umbilical vein showed normal nonpulsatile blood flow pattern in every case. In study group 2 all the fetuses had atrial pulsations in the intraabdominal umbilical vein. After delivery blood samples were collected from the umbilical arteries, and cardiac troponin T concentrations were measured with commercially available enzyme-linked immunosorbent assay kits. A clinically significant troponin T level was set at ≥0.10 ng/mL. Results: In study group 1 the maternal main uterine arterial blood flow pattern was normal in 30 cases and abnormal in 2 cases. Umbilical artery blood velocity waveforms were normal in 26 fetuses, 4 fetuses had a decreased diastolic blood flow, 1 fetus had an absent diastolic blood flow pattern, and 1 fetus had a retrograde diastolic blood flow pattern. In study group 2 maternal uterine arterial Doppler findings were abnormal in every case, and all the fetuses had retrograde diastolic blood flow pattern in the umbilical artery. Neonatal troponin T levels were <0.10 ng/mL in the control group (0-0.14 ng/mL) and in study group 1 (0-0.16 ng/mL), except for 1 case in each group. Every neonate in study group 2 had a troponin T level >0.10 ng/mL, with the range from 0.11 to 0.35 ng/mL. In study group 2 troponin T concentrations were significantly higher (P <.0001) than in either the control group or study group 1. Conclusion: Neonatal troponin T levels are not clinically significantly increased in normal pregnancies and in pregnancies complicated by maternal hypertensive disorder but with normal fetal umbilical venous return. Neonatal troponin T concentrations are significantly increased in the presence of abnormal umbilical venous return, which indicates myocardial cell damage. (Am J Obstet Gynecol 2000;183:726-31.)

Umbilical Arterial S-nitrosothiols in Stressed Newborns: Role in Perinatal Circulatory Transition

S-Nitrosothiols are potent endogenous vasodilators recently found to be in greater concentrations in fetal umbilical venous than arterial blood. We hypothesized that neonatal increases in SNOs may be involved in the normal human perinatal circulatory transition. Paired human umbilical artery and vein plasma samples were collected after birth. S-Nitrosothiol concentrations were measured as NO after photolysis—and NO−3after reduction in vanadium chloride—by chemiluminescence. Normal umbilical arterial serum SNO levels were nearly twice those of matched venous samples but were low in infants who did not transition normally to neonatal circulation. There was no difference in the concentration of NO−3between the normal and depressed infants. The parallel failure of some fetuses to switch both to a normal arteriovenous SNO relationship and a normal clinical post-partum state suggests that SNOs may be involved in the perinatal circulatory transition.

The Effect of Fetal Intravascular Blood Transfusion on Plasma Endothelin Levels in Fetuses With Rhesus Alloimmunization

In Brief Objective To determine if intrauterine intravascular fetal transfusion affects fetal umbilical venous endothelin levels. Methods Endothelin concentrations were measured by radioimmunoassay in fetal umbilical venous blood obtained immediately before and after 36 fetal transfusions performed for Rh alloimmune hemolytic anemia. Umbilical venous pressures also were recorded before and after transfusion. Results The mean (± standard deviation [SD]) gestational age at transfusion was 27.0 ± 4.6 weeks, whereas the initial and post-transfusion hematocrits were 23.3 ± 8.5% and 41.8 ± 6.3%, respectively. Post-transfusion endothelin levels correlated significantly with the volume of transfused blood (r = .41; P = .03) and with post-transfusion increases in umbilical vein pressure (r = .86; P < .001). Among fetuses undergoing initial transfusion, there were significant differences between mean (± SD) pre- and post-transfusion endothelin levels [3.6 (± 2.2) pg/mL versus 6.3 (± 4.0) pg/mL, respectively; P = .02]. In contrast, among fetuses undergoing a repeat fetal transfusion, no differences in mean (± SD) pre-versus post-transfusion endothelin levels were observed [3.8 (± 1.8) pg/mL versus 2.2 (± 1.77) pg/mL, respectively; P = .3)]. Step-wise multiple regression analysis identified order of transfusion as a significant predictor of change in endothelin levels from pre- to post-transfusion measurements (adjusted r2 = .26; P = .003). Conclusion Rapid expansion of fetal intravascular volume by intravenous transfusion of packed red blood cells with a high hematocrit enhances fetal endothelin levels in those fetuses undergoing initial but not subsequent transfusions. Endothelin concentrations increase with initial intravascular transfusion for fetal anemia in cases of Rh alloimmunization.

The Effect of Fetal Intravascular Blood Transfusion on Plasma Endothelin Levels in Fetuses With Rhesus Alloimmunization

Objective: To determine if intrauterine intravascular fetal transfusion affects fetal umbilical venous endothelin levels. Methods: Endothelin concentrations were measured by radioimmunoassay in fetal umbilical venous blood obtained immediately before and after 36 fetal transfusions performed for Rh alloimmune hemolytic anemia. Umbilical venous pressures also were recorded before and after transfusion. Results: The mean (± standard deviation [SD]) gestational age at transfusion was 27.0 ± 4.6 weeks, whereas the initial and post-transfusion hematocrits were 23.3 ± 8.5% and 41.8 ± 6.3%, respectively. Post-transfusion endothelin levels correlated significantly with the volume of transfused blood ( r = .41; P = .03) and with post-transfusion increases in umbilical vein pressure ( r = .86; P < .001). Among fetuses undergoing initial transfusion, there were significant differences between mean (± SD) pre- and post-transfusion endothelin levels [3.6 (± 2.2) pg/mL versus 6.3 (± 4.0) pg/mL, respectively; P = .02]. In contrast, among fetuses undergoing a repeat fetal transfusion, no differences in mean (± SD) pre- versus post-transfusion endothelin levels were observed [3.8 (± 1.8) pg/mL versus 2.2 (± 1.77) pg/mL, respectively; P = .3)]. Step-wise multiple regression analysis identified order of transfusion as a significant predictor of change in endothelin levels from pre- to post-transfusion measurements (adjusted r 2 = .26; P = .003). Conclusion: Rapid expansion of fetal intravascular volume by intravenous transfusion of packed red blood cells with a high hematocrit enhances fetal endothelin levels in those fetuses undergoing initial but not subsequent transfusions.

Anesthetic Management of Cesarean Delivery Complicated by Ex Utero Intrapartum Treatment of the Fetus

Anesthetic Management of Cesarean Delivery Complicated by Ex Utero Intrapartum Treatment of the Fetus