Parasympathetic nervous system response to acidosis: Evaluation in an experimental fetal sheep model

INTRODUCTION

Heart rate variability and fetal heart rate decelerations are impacted by parasympathetic function and reflect acid-base status. Our team developed a new heart rate variability index, the fetal stress index (FSI), which has lower interindividual variability and higher sensitivity for detecting fluctuations in parasympathetic nervous system activity. The aim of this study was to explore the ability of the FSI to predict fetal acidosis in a fetal sheep model.

MATERIAL AND METHODS

Repeated 1-minute total umbilical cord occlusions (UCOs) were performed every 2.5 minutes over 3 hours to generate fetal acidosis mimicking that which occurs during labor and contractions. Fetal hemodynamic parameters, blood gas, the FSI and the magnitude (from the beginning to the nadir) of the fetal heart rate deceleration were recorded at regular intervals. The data were analyzed over three time intervals because of variation in the duration of the experiments: period A (first 12 UCOs), period B (middle 12 UCOs) and period C (last 12 UCOs).

RESULTS

Nine experiments were performed. Acidosis was progressive with a significant difference between the pH, lactate levels and base deficit values for the three periods of occlusion (P < 0.05). Both FSI and the magnitude of fetal heart rate decelerations gradually increased during the UCOs and both differed significantly between periods A and C (P = 0.0008 for FSI and P = 0.003 for deceleration).

CONCLUSION

This experimental protocol allowed the development of progressive acidosis in a good model of the physiology of labor. Parasympathetic nervous system activity increased during acidosis and could be measured using our index, the FSI, and the magnitude of fetal heart rate decelerations.

Role of fetal ultrasound and magnetic resonance imaging in the prenatal diagnosis of migration disorders

OBJECTIVES

To evaluate the contribution and limitations of fetal ultrasonography (US) and magnetic resonance imaging (MRI) for the diagnosis and management of migration disorders.

METHODS

Over a 5-year period, 14 fetuses with pathological migration disorders, without an infectious context, were taken care of in our centre. All underwent US; nine underwent MRI as well. Sonographic and MRI data were compared with neuropathological data.

RESULTS

The diagnosis of gyral disorders was obtained by US in 1/14 cases; other cerebral abnormalities were found suggesting neuronal disorder in the remainder. Cerebral MRI suggested gyral abnormality in eight of the nine cases.

CONCLUSIONS

US performance is increasing. MRI appears to be a promising method for the diagnosis of fetal migration disorders, giving better results than US. It may be recommended in cases of abnormal cerebral US findings or familial clinical history. However, interpretation of MRI can be tricky and the resulting diagnosis occurs late within the pregnancy.

Neonatal outcome after fetal anemia managed by intrauterine transfusion

In-utero transfusion is now well under control and improves the survival of foetuses monitored for fetal anemia with a survival rate of more than 80 %. The aim was to evaluate short-term neonatal outcome after fetal severe anemia managed by intrauterine transfusions. We did a retrospective study of all neonates born after management of severe fetal anemia (n = 93) between January 1999 and January 2013 in our regional center. The two main causes of anemia were maternal red blood cell alloimmunization (N = 81, 87 %) and Parvovirus B19 infection (N = 10, 10.8 %). In the alloimmunization group, phototherapy was implemented in 85.2 % of cases with a maximum level of bilirubin of 114.4 ± 60.7 (mg/dl). Transfusion and exchange transfusion were, respectively, required in 51.9 % and in 34.6 % of cases. One neonate presented a convulsive episode, and we observed three neonatal deaths. In the parvovirus group, none of the child had anemia at birth and no management was necessary.

CONCLUSION

Contemporary management of Rhesus disease is associated with encouraging neonatal outcomes. In case of Parvovirus infection, no specific management is necessary at. But, in all cases of fetal anemia, children should be followed up with particular attention to neurologic development.

WHAT IS KNOWN

• In-utero transfusion is now well under control and improves the survival of fetuses monitored for fetal anemia. • Limited studies are available on the effect of IUT on postnatal outcome in infants with a history of fetal anemia. What is New: • Contemporary management of severe Rhesus disease is associated with encouraging neonatal outcomes. • The majority of infants can be managed with phototherapy and a limited number of top-up transfusions and exchange transfusions. In case of Parvovirus infection, the short-term neonatal outcome is excellent.

Prenatal prediction of postnatal survival in fetuses with congenital diaphragmatic hernia using MRI: lung volume measurement, signal intensity ratio, and effect of experience

Objective: To evaluate various signal intensity ratios in isolated congenital diaphragmatic hernia (CDH) and to compare their potential in predicting survival with that of the observed-to-expected (O/E) ratio of total fetal lung volume (TFLV) using magnetic resonance imaging (MRI) measurements. Our second objective was to evaluate the impact of operator's experience in comparing the prediction of postnatal survival by O/E-TFLV.Methods: In 75 conservatively managed CDH fetuses and in 50 who underwent fetoscopic endoluminal tracheal occlusion (FETO), the fetal lung-to-amniotic fluid, lung-to-liver, lung-to-muscle, lung-to-spinal fluid signal intensity ratios, respectively LAFSIR, LLSIR, LMSIR, and LSFSIR, were measured, as was O/E-TFLV. Receiver operating characteristic (ROC) curves were constructed and used to compare the various signal intensity ratios with O/E-TFLV in the prediction of postnatal survival. In 72 MRI lung volumes assessed by the referring radiologists in Paris and Lille and secondarily by our expert radiologist in Brussels (M.M.C.) using the same MRI examinations, ROC curves were constructed and used to compare the value of O/E-TFLV determined by the two centers in the prediction of postnatal survival.Results: In the total cohort of CDH fetuses, O/E-TFLV and LLSIR were predictive of postnatal survival whereas in the conservatively managed group O/E-TFLV, LLSIR, and LMSIR predicted postnatal survival. O/E-TFLV predicted postnatal survival far better than the signal intensity ratios: area under the ROC curve for prediction by O/E-TFLV in the total cohort was 0.866 (p < .001; standard error = 0.031). The area under the ROC curve for prediction of postnatal survival using O/E-TFLV by MRI evaluated at the referral centers was 0.640 (p = 102; standard error = 0.085), and with O/E-TFLV reevaluated by M.M.C., it was 0.872 (p < .001; standard error = 0.061). Pairwise comparison showed a significant difference between the areas under the ROC curves (difference = 0.187, p = .012; standard error = 0.075).Conclusion: In fetuses with CDH with/without FETO, LLSIR was significantly correlated with the prediction of postnatal survival. However, measurement of O/E-TFLV was far better in predicting postnatal outcome. Operator experience in measurement of lung volumes using MRI seem to play a role in the predictive value of the technique.

Effets maternels et fœtaux d'une prise de poids maternelle excessive au cours de la grossesse dans une population de patientes de poids normal avant la grossesse

OBJECTIVE

To study the effects of increased gestational weight gain in women of normal prepregnant weight.

PATIENTS AND METHODS

We compared 174 patients gaining more than 18 kg to 174 patients gaining between 9 and 15 kg. Body mass index was normal for every woman included in the study.

RESULTS

Weight gain > or =18 kg was associated with increased risk of vascular complications (5.2% vs. 1.1%, P < 0.05) but not with increased risk of mellitus diabetes (5.2% vs. 4.0%, NS). Weight gain > or =18 kg prolonged labor length (414.4 +/- 147 min vs. 376.5 +/- 166.4 min, P < 0.05) and increased the rate of cesarean section (19.5% vs. 10.3%, P < 0.05). Neonatal outcome was similar in both groups, mean birth weight was greater (3413.6 +/- 427.0 g vs. 3163.4 +/- 495.1 g, P < 0.05) and the frequency of infants weighing more than 4000 g at birth was increased (8.0% vs. 4.0%, P < 0.05) among women gaining more than 18 kg.

CONCLUSION

Excess weight gain in pregnancy affects gestational and delivery outcomes and results in higher frequency of fetal macrosomia. These results confirm recommendations on weight gain in pregnancy as guidelines for pregnant women.

Anesthésie maternofœtale pour « ex utero intrapartum » traitement (EXIT) procédure : à propos de deux cas

The ex utero intrapartum treatment (EXIT) procedure is a surgical procedure maintaining utero-placental circulation during caesarean section. Anaesthetic implications are described: foetal transplacental anaesthesia to avoid first breathing and to permit surgical procedure on obstructed foetal airway, deep maternal haemodynamically stable anaesthesia to relax uterine smooth muscle during a long caesarean procedure but avoiding post-partum haemorrhage. Volatile anaesthesia with sevoflurane seems to be adequate for these aims. Two cases are described.

Intervalle de naissance entre les jumeaux: une limite de temps est-elle justifiée?

OBJECTIVES

To assess the effect of the twin-to-twin delivery interval on the umbilical cord blood gas status and the neonatal outcome of the second twin following vaginal delivery.

PATIENTS AND METHODS

Retrospective study of twin deliveries at or beyond 34 weeks of gestation over a period of five years. The correlation between the twin-to-twin delivery interval, and the umbilical arterial blood gas parameters of the second twin, including pH, PO(2), PCO(2), HCO(3-) and base excess, was studied. A second analysis was performed after exclusion of non-vertex presentation, need for general anesthesia, growth restriction and weight difference between the twin>30%.

RESULTS

Two hundred and thirty-nine patients were studied. The mean twin-to-twin delivery interval was 11.3+/-6.4 minutes (between 6 and 14 minutes in 56.1% of cases). The second twin had more Apgar score<7 at 1 minute (P<0.02) and more arterial ombilical pH<7.20 (P<0.01) than the first twin. Over 15 minutes, the mean arterial pH was lower (P<0.01) and the number of arterial pH<7.20 increased (P<0.03). In contrast, the mean Apgar score and the rate of neonatal transfer did not differ significantly. There were significant negative correlations between arterial pH, base excess and bicarbonates and the twin-to-twin delivery interval (P<0.05). Similar results were found in the homogenised population. The reduction in the second twin arterial pH was expressed as pH=7.282-0.003 x time.

DISCUSSION AND CONCLUSION

Umbilical cord arterial blood gas parameters deteriorate with increasing twin-to-twin delivery interval. Our results suggest that this interval should be less than 15 minutes, but obstetrician should adapt to every clinic situation.

Correlation of a new index reflecting the fluctuation of parasympathetic tone and fetal acidosis in an experimental study in a sheep model

The autonomic nervous system plays a leading role in the control of fetal homeostasis. Fetal heart rate variability (HRV) analysis is a reflection of its activity. We developed a new index (the Fetal Stress Index, FSI) reflecting parasympathetic tone. The objective of this study was to evaluate this index as a predictor of fetal acid-base status. This was an experimental study on chronically instrumented fetal lambs (n = 11, surgery at 128 +/- 2 days gestational age, term = 145 days). The model was based on 75% occlusion of the umbilical cord for a maximum of 120 minutes or until an arterial pH ≤ 7.20 was reached. Hemodynamic, gasometric and FSI parameters were recorded throughout the experimentation. We studied the FSI during the 10 minutes prior to pH samplings and compared values for pH>7.20 and pH≤ 7.20. In order to analyze the FSI evolution during the 10 minutes periods, we analyzed the minimum, maximum and mean values of the FSI (respectively FSImin, FSImax and FSImean) over the periods. 11 experimentations were performed. During occlusion, the heart rate dropped with an increase in blood pressure (respectively 160(155-182) vs 106(101-120) bpm and 42(41-45) vs 58(55-62) mmHg after occlusion). The FSImin was 38.6 (35.2-43.3) in the group pH>7.20 and was higher in the group pH less than 7.20 (46.5 (43.3-52.0), p = 0.012). The correlation of FSImin was significant for arterial pH (coefficient of -0.671; p = 0.004) and for base excess (coefficient of -0.632; p = 0.009). The correlations were not significant for the other parameters. In conclusion, our new index seems well correlated with the fetal acid-base status. Other studies must be carried out in a situation close to the physiology of labor by sequential occlusion of the cord.

Randomised comparison of uterine artery Doppler and aspirin (100 mg) with placebo in nulliparous women: the Essai Régional Aspirine Mère-Enfant study (Part 2)

OBJECTIVE

To assess the effectiveness of a pre-eclampsia prevention strategy based on routine uterine artery Doppler flow velocity waveform examination during the second trimester of pregnancy, followed by a prescription for 100 mg aspirin in the case of abnormal Doppler findings.

DESIGN

Multicentre randomised controlled trial.

SETTING

Eleven centres in the north of France and one in Belgium.

POPULATION

One thousand and eight hundred and fifty-three nulliparous women recruited between 14 and 20 weeks of gestation.

METHODS

Randomisation either to undergo a uterine Doppler examination between 22 and 24 week of gestation or to take a placebo. Women with abnormal Doppler waveforms received 100 mg of aspirin daily from Doppler examination through 36 weeks.

MAIN OUTCOME MEASURES

Pre-eclampsia was defined as hypertension (> or = 140 and/or 90 mmHg) associated with proteinuria (> or = 0.5 g/L).

RESULTS

One thousand two hundred and fifty-three women (67%) were randomised into the systematic Doppler group and 617 (33%) into the placebo group. Of the 1175 patients in the Doppler group who underwent this examination, 239 (20.3%) had abnormal uterine artery Doppler and received a prescription for aspirin. Despite the aspirin prescription, the frequency of pre-eclampsia did not differ between the systematic Doppler group and the placebo group (28 of 1237 [2.3%] vs 9 of 616 [1.5%]; RR = 1.55, 95% CI 0.7-3.3). Furthermore, the groups did not differ in the frequency of children who were very small for their gestational age (< or =3rd centile) or for perinatal deaths. Compared with patients with normal Doppler findings, those with abnormal Doppler were at high risk of pre-eclampsia (RR = 5.5, 95% CI 2.5-12.2) and of giving birth to a small-for-gestational-age child (RR = 3.6, 95% CI 1.6-8.1).

CONCLUSION

Despite its sensitivity in screening for pre-eclampsia, routine uterine Doppler in the second trimester cannot be recommended for nulliparous patients.

[Hyperemesis in the first trimester of pregnancy: role of biological hyperthyroidism and fetal sex]

OBJECTIVES

Our objectives were to link hyperemesis gravidarum with biochemical hyperthyroidism and hormonal modification (HCG and estradiol) and to test the hypothesis that biological abnormalities (ionogram and liver enzyme) are more often reported in hyperemesis gravidarum with biochemical hyperthyroidism.

STUDY DESIGN

Thirty three patients admitted in "Hôpital Jeanne de Flandre" with hyperemesis gravidarum were studied prospectively.

RESULTS

Twenty-two patients (66.7%) had biochemical hyperthyroïdsm (suppressed thyroid stimulating hormone or increased triiodothyronine index or tetraiodothyronine index). Hyperthyroid patients were more likely than euthyroid patients to have abnormal electrolyte levels (16/22 [72.7%] vs 3/1 [27.3%], P < 0.02) or increased liver enzyme levels (8/22 [36.4%] vs 3/11 [27.3%]). The severity of hyperemesis was found to vary directly with the degree of hyperthyroidism. We report a female predominance among the offspring of mothers with hyperemesis gravidarum.

CONCLUSION

Our results are suggestive of the involvement of hyperthyroidism and fetal sex in the pathogenesis of hyperemesis gravidarum. Also these hypothesis are not clearly understood, human chorionic gonadotrophin occurred in the two mechanisms.

Effects of Antenatal Glucocorticoids on Circulatory Adaptation at Birth in the Ovine Fetus

OBJECTIVE

Adaptation to extra-uterine life requires dramatic increase in pulmonary blood flow. Mechanisms that induce pulmonary vasodilatation at birth are incompletely understood but include alveolar ventilation, increase in PaO2, and production of vasoactive mediators. We hypothesized that antenatal glucocorticoids (GC) increase pulmonary vasodilatation to birth-related stimuli.

STUDY DESIGN

To test this hypothesis, we studied the pulmonary hemodynamic response at birth to mechanical ventilation with low (<10%) and then with high (100%) FiO2 in chronically prepared late-gestation fetal lambs treated or not by antenatal maternal steroids.

RESULTS

Basal mean aortic and pulmonary artery pressure (PAP), left pulmonary blood flow, pulmonary vascular resistance (PVR), and blood gas were similar between control and dexamethasone-treated animals (GC group). During mechanical ventilation with low FiO2, mean PVR decreased by 40% in the control group (from 0.44 +/- 0.01 to 0.25 +/- 0.01 mm Hg/ml/min) and by 60% in the GC group (from 0.44 +/- 0.02 to 0.19 +/- 0.02 mm Hg/ml/min) (p < 0.01). When subsequently ventilated with 100% O2, there was no difference in PVR decrease between groups (0.15 +/- 0.02 mm Hg/ml/min in the GC group vs. 0.14 +/- 0.01 mm Hg/ml/min in the control group).

CONCLUSION

Antenatal GC enhance pulmonary vasodilatation induced by alveolar ventilation at birth but do not alter the pulmonary vascular response to O2. We speculate that antenatal steroids exposure improve adaptation at birth through acceleration of both parenchymal and vascular lung maturation.

In utero treatment of severe fetal anemia resulting from fetomaternal red blood cell incompatibility: a comparison of simple transfusion and exchange transfusion

OBJECTIVE

To compare in utero exchange transfusions (IUET) and in utero simple transfusions (IUST) for the treatment of fetal anemia resulting from red blood cell fetomaternal incompatibility.

STUDY DESIGN

Retrospective comparative study from January 2006 through December 2011. The two techniques were compared for effectiveness, complications, and neonatal outcomes.

RESULTS

36 patients had 87 IUETs and 85 patients 241 IUSTs. Gestational age at the first transfusion was similar in both groups (IUET: 27±3.8 weeks; IUST: 27±4.7 weeks; NS) as was the initial fetal hemoglobin level (IUET: 6.4±2.8g/dL; IUST: 6.0±2.5g/dL; NS). No significant differences were noted for postprocedure complications or efficacy. The daily drop in hemoglobin level was similar in both groups (IUET: 0.41±0.23g/dL/day; IUST: 0.44±0.17g/dL/day; NS) as were the time intervals between two procedures. Gestational age at birth was earlier in the IUET group (34.4±1.3 weeks vs 35.5±1.8 weeks; p<0.001), but the postnatal transfusions or exchange transfusions rates and the duration of intensive phototherapy did not differ. No significant differences were noted for the overall survival rates (IUET: 100%; IUST: 96.4%; p>0.99).

CONCLUSION

IUET does not appear to provide any benefits compared with IUST, neither to be associated with a higher complication rate. The choice of the technique depends on availability of packed blood cells with high hematocrit (70-80%).

Tracheal occlusion alters pulmonary circulation in the fetal lamb with normally developing lungs

BACKGROUND

Tracheal occlusion (TO) promotes fetal lung growth through an increase in intraluminal pressure. Although evidence suggests that fetal TO (FETO) decreases the occurrence of pulmonary hypertension in severe congenital diaphragmatic hernia, controversies on its effect on the pulmonary circulation remain. Therefore, we investigated the effects of FETO on the lung hemodynamics in a chronically catheterized fetal lamb model.

METHODS

Fifteen pregnant ewes were operated on between 125 and 128 days of gestation (term: 145 days). Catheters and ultrasonic flow transducer were placed through a left thoracotomy in the lamb fetus to determine aortic, pulmonary and left atrial pressures, and left pulmonary artery blood flow. A balloon was positioned between the carina and vocal cords under fetoscopic control. The animals were assigned to either control (n=6) or FETO (n=9) groups. TO was performed by inflating the balloon. We studied the acute effects of temporary (2-h) and prolonged (4-day) TO on basal pulmonary vascular tone and on the pulmonary vascular reactivity to acetylcholine and to increased fetal oxygen tension.

RESULTS

We found that left pulmonary blood flow (LPA) increased and pulmonary vascular resistance (PVR) decreased by 20% during brief TO (p<0.05). After balloon deflation, LPA blood flow further increased by 40%, and PVR decreased by 50% compared to baseline values (p<0.05). In contrast, no change in LPA blood flow or PVR was observed during prolonged TO. Moreover, the vasodilator responses to acetylcholine and to increased fetal PaO2 were blunted during TO.

CONCLUSIONS

These data indicate that antenatal tracheal occlusion promotes active pulmonary vasodilation, which is partly blunted by the mechanical effects of elevation of the intraluminal pressure.

[Abruptio placentae. Management in a reference Nigerien maternity. Prospective study about 118 cases during one year]

OBJECTIVE

Placental abruption is a syndrome, which occurs in the third trimester of the pregnancy or during labour. It is the main cause of pregnancy last term bleeding and is also responsible for a high stillbirth rate. The objective is to describe the epidemiological, clinical, paraclinical and therapeutic characteristics in order to decrease the fetal and maternal mortality and morbidity.

PATIENTS AND METHODS

It is a prospective and descriptive study in continuous series, over a twelve-month period, from 1st January 2003 to 31st December 2003, at Issaka Gazobi maternity of Niamey, Niger.

RESULTS

During the study period, 3255 deliveries have been done. One hundred and eighteen placental abruptions have been observed, which corresponds to a frequency of 3.6% with the highest rate during raining season. The average age and parity were: 31 years and 5th with a predominance of grand multiparous (38.2%). The majority of the patients were in-utero transfers (83,1%) and had done at least 10 km before arriving. One hundred and eleven patients had a caesarean section (94,1%) and 7 delivered through the vaginal route (5.9%). The fetal prognosis was characterized by a high stillbirth rate of 71.3% (87/122), fetal hypotrophy (64.8%) and prematurity (23.8%). The main cause of maternal morbidity was anaemia (76.3%) and Disseminated Intravascular Coagulation (5.9%). Further, 81 patients have been transfused (68.7%). The maternal mortality was 5.1% (6/118).

DISCUSSION AND CONCLUSION

Placental abruption, a medical and obstetrical emergency, is a serious obstetric condition, especially in our country. Physicians must be aware that patients with high blood pressure, preeclampsia, eclampsia, particularly in case of multiparity are at increased risk of placental abruption. Early diagnosis, prenatal follow-up and caesarean section improve the maternal and fetal prognosis.

Transposition of the great arteries: factors influencing prenatal diagnosis

OBJECTIVE

The objective of this study is to highlight the factors that may affect prenatal diagnosis of transposition of the great arteries (TGA) in order to improve it.

METHODS

This is a retrospective study performed between 2004 and 2009 in the maternity units from North of France. We identified a total of 68 cases of TGA (isolated or associated with only VSD or coarctation of aorta), of which 32 (47.1%) had prenatal diagnosis (PND+) and 36 did not (PND-). Maternal characteristics and ultrasound factors were studied in relation to PND.

RESULTS

Maternal weight and body mass index were significantly higher in the PND- group (70.4 kg and 26.5 kg/m(2) vs 63.6 kg and 23.6 kg/m(2) , respectively). Maternal obesity (body mass index >30) was significantly more frequent in the PND- group (27.8% vs 12.5%). More than a quarter of TGA (28.1%) were diagnosed during the third trimester.

CONCLUSION

Obesity is the main cause of missed PND of TGA. Obese patients with suboptimal prenatal scans may benefit from reassessment of fetal cardiac anatomy and/or from referral for fetal echocardiography.