State 1F Research Articles

Fetal Heart Rate Analysis in Pregnancies Complicated by Gestational Diabetes Mellitus: A Prospective Multicentre Observational Study.

Establish whether pregnancies complicated by gestational diabetes mellitus (GDM) are associated with a fetal cardiac phenotype that predisposes to arrhythmia; utilising measurements derived from non-invasive abdominal fetal ECG. Prospective observational study. Three tertiary obstetric units, United Kingdom. Women aged ≥ 16 years with either GDM or uncomplicated pregnancy (control) who were > 20 weeks gestational age. The MonicaAN24 non-invasive abdominal fetal ECG monitor was fitted for overnight recording. Calculation of the fetal heart rate (FHR) and fetal heart rate variability (HRV) time domain metrics standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD) and the PR, QRS, QT intervals was performed. Groups were compared using linear regression models (stratified by sleep state) and adjusted for fetal sex and ethnicity. Ninety-six participants were included. For HRV in sleep state 1F, SDNN was higher for GDM than control participants 12.56 (10.45-16.62)ms versus 8.58 (5.83-9.73)ms [p = 0.01] [median (IQR)]. There were no differences in SDNN in sleep state 2F. No differences were identified in RMSSD in either sleep states or in the cardiac time intervals. We observed a negative correlation between HRV and body mass index/HbA1c and a positive correlation between FHR and body mass index/HbA1c in sleep states 1F/2F. Alterations of HRV and FHR rate may be associated with a diagnosis of GDM, likely secondary to altered autonomic function in utero.

THEORETICAL STUDYING SPECTRAL CHARACTERISTICS OF Tm ATOM WITHIN OPTIMIZED RELATIVISTIC MANY-BODY THEORY

Theoretical studying Rydberg spectrum of complex lanthanide atom of Tm has been performed within the relativistic many-body perturbation theory and generalized relativistic energy approach. The zeroth approximation of the relativistic perturbation theory is provided by the optimized Dirac-Kohn-Sham-Breit ones. Optimization has been fulfilled by means of introduction of the special gauge parameter to the Fock and Kohn-Sham exchange potentials and further minimization of the gauge-non-invariant contributions into radiation width of atomic levels with using relativistic orbital sets, generated by the corresponding zeroth approximation Hamiltonian. The calculated energies and widths of autoionization resonant states 4f--1j 6s(J12)nsnp[J] of the Tm atom with n=25-35 are presented and compared with known theoretical results, received within other approaches. Two main types of the Rydberg autoionization resonances decay, namely, the classic Beutler-Fano decay channel and a new Ivanov et al reorientation-type decay channel ar4e studied. It is noted that, for example, for autoionization resonant states with the considered values of n, the decay of resonances occurs along both channels, and it is extremely difficult to understand a priori which of them is dominant.

Effects of Prenatal Exposure to Alcohol and Smoking on Fetal Heart Rate and Movement Regulation.

Negative associations of prenatal tobacco and alcohol exposure (PTE and PAE) on birth outcomes and childhood development have been well documented, but less is known about underlying mechanisms. A possible pathway for the adverse fetal outcomes associated with PTE and PAE is the alteration of fetal autonomic nervous system development. This study assessed PTE and PAE effects on measures of fetal autonomic regulation, as quantified by heart rate (HR), heart rate variability (SD-HR), movement, and HR-movement coupling in a population of fetuses at ≥ 34 weeks gestational age. Participants are a subset of the Safe Passage Study, a prospective cohort study that enrolled pregnant women from clinical sites in Cape Town, South Africa, and the Northern Plains region, United States. PAE was defined by six levels: no alcohol, low quit early, high quit early, low continuous, moderate continuous, and high continuous; while PTE by 4 levels: no smoking, quit early, low continuous, and moderate/high continuous. Linear regression analyses of autonomic measures were employed controlling for fetal sex, gestational age at assessment, site, maternal education, household crowding, and depression. Analyses were also stratified by sleep state (1F and 2F) and site (South Africa, N = 4025, Northern Plains, N = 2466). The final sample included 6491 maternal-fetal-dyad assessed in the third trimester [35.21 ± 1.26 (mean ± SD) weeks gestation]. PTE was associated with a decrease in mean HR in state 2F, in a dose dependent fashion, only for fetuses of mothers who continued smoking after the first trimester. In state 1F, there was a significant increase in mean HR in fetuses whose mother quit during the first trimester. This effect was driven by the Norther Plains cohort. PTE was also associated with a significant reduction in fetal movement in the most highly exposed group. In South Africa a significant increase in mean HR both for the high quit early and the high continuous group was observed. In conclusion, this investigation addresses a critical knowledge gap regarding the relationship between PTE and PAE and fetal autonomic regulation. We believe these results can contribute to elucidating mechanisms underlying risk for adverse outcomes.

A pilot study: Auditory steady-state responses (ASSR) can be measured in human fetuses using fetal magnetoencephalography (fMEG).

BackgroundAuditory steady-state responses (ASSRs) are ongoing evoked brain responses to continuous auditory stimuli that play a role for auditory processing of complex sounds and speech perception. Transient auditory event-related responses (AERRs) have previously been recorded using fetal magnetoencephalography (fMEG) but involve different neurological pathways. Previous studies in children and adults demonstrated that the cortical components of the ASSR are significantly affected by state of consciousness and by maturational changes in neonates and young infants. To our knowledge, this is the first study to investigate ASSRs in human fetuses.Methods47 fMEG sessions were conducted with 24 healthy pregnant women in three gestational age groups (30–32 weeks, 33–35 weeks and 36–39 weeks). The stimulation consisted of amplitude-modulated (AM) tones with a duration of one second, a carrier frequency (CF) of 500 Hz and a modulation frequency (MF) of 27 Hz or 42 Hz. Both tones were presented in a random order with equal probability adding up to 80–100 repetitions per tone. The ASSR across trials was quantified by assessing phase synchrony in the cortical signals at the stimulation frequency.Results and conclusionTen out of 47 recordings were excluded due to technical problems or maternal movements. Analysis of the included 37 fetal recordings revealed a statistically significant response for the phase coherence between trials for the MF of 27 Hz but not for 42 Hz. An exploratory subgroup analysis moreover suggested an advantage in detectability for fetal behavioral state 2F (active asleep) compared to 1F (quiet asleep) detected using fetal heart rate. In conclusion, this pilot study is the first description of a method to detect human ASSRs in fetuses. The findings warrant further investigations of the developing fetal brain.

Peculiarities of positioning of electronic states 4f and 5d of Pr ionin the matrix LaF\textsubscript{3}

Peculiarities of positioning of electronic states 4f and 5d of Pr ionin the matrix LaF\textsubscript{3}

An investigation of fetal behavioural states during maternal sleep in healthy late gestation pregnancy: an observational study.

Fetal behavioural state in healthy late gestation pregnancy is significantly affected by maternal position overnight. Maternal left lateral position is the one most frequently adopted at sleep onset. The maternal position at sleep onset is maintained the longest overnight. Fetal state 1F is more common in maternal supine positions overnight. Fetal state 4F is less common in maternal supine sleep positions. Fetal state and maternal sleep position are independently associated with fetal heart rate variability. Maternal sleep position significantly affects fetal heart rate and heart rate variability and affects circadian fetal heart rate patterns. Fetal behavioural states (FBS) are measures of fetal wellbeing. Maternal position affects FBS with supine position being associated with an increased likelihood of fetal quiescence consistent with the human fetus adapting to a lower oxygen consuming state. Several studies have now confirmed the association between sleep position and risk of late intrauterine death. We designed this study to observe the effects of maternal sleep positions overnight in healthy late gestation pregnancy. Twenty-nine healthy women had continuous fetal ECG recordings overnight. Two blinded observers assigned fetal states in 5min blocks. Measures of fetal heart rate variability (FHRV) were calculated from ECG beat to beat data. Maternal position was determined from infrared video recording. Compared to state 2F (active sleep), 4F (active awake-high activity) occurred almost exclusively when the mother was in a left or right lateral position. State 1F (quiet sleep) was more common when the mother was supine [odds ratio (OR) 1.30, 95% confidence interval (CI) 1.11-1.52] and less common on the maternal right side with the left being the referent position (OR 0.81, 95% CI, 0.70-0.93). State 4F was more common between 21.00 and 01.00h than between 01.00 and 07.00h (OR 2.83, 95% CI 2.32-3.47). In each fetal state, maternal position had significant effects on fetal heart rate and measures of FHRV. In healthy late gestation pregnancy, maternal sleep position affects FBS and heart rate variability. These effects are probably fetal adaptations to positions which may produce a mild hypoxic stress.

Effect of maternal position on fetal behavioural state and heart rate variability in healthy late gestation pregnancy

Fetal behavioural state in healthy late gestation pregnancy is affected by maternal position. Fetal state 1F is more likely to occur in maternal supine or right lateral positions. Fetal state 4F is less likely to occur when the woman lies supine or semi-recumbent. Fetal state change is more likely when the woman is supine or semi-recumbent. Fetal heart rate variability is affected by maternal position with variability reduced in supine and semi-recumbent positions. Fetal behavioural states (FBS) are measures of fetal wellbeing. In acute hypoxaemia, the human fetus adapts to a lower oxygen consuming state with changes in the cardiotocograph and reduced fetal activity. Recent studies of late gestation stillbirth described the importance of sleep position in the risk of intrauterine death. We designed this study to assess the effects of different maternal positions on FBS in healthy late gestation pregnancies under controlled conditions. Twenty-nine healthy women had continuous fetal ECG recordings under standardized conditions in four randomly allocated positions, left lateral, right lateral, supine and semi-recumbent. Two blinded observers, assigned fetal states in 5min blocks. Measures of fetal heart rate variability were calculated from ECG beat to beat data. Compared to state 2F, state 4F was less likely to occur when women were semi-recumbent [odds ratio (OR)=0.11, 95% confidence interval (95% CI) 0.02, 0.55], and supine (OR=0.27, 95% CI 0.07, 1.10). State 1F was more likely on the right (OR=2.36, 95% CI 1.11, 5.04) or supine (OR=4.99, 95% CI 2.41, 10.43) compared to the left. State change was more likely when the mother was semi-recumbent (OR=2.17, 95% CI 1.19, 3.95) or supine (OR=2.67, 95% CI 1.46, 4.85). There was a significant association of maternal position to mean fetal heart rate. The measures of heart rate variability (SDNN and RMSSD) were reduced in both semi-recumbent and supine positions. In healthy late gestation pregnancy, maternal position affects FBS and heart rate variability. These effects are likely fetal adaptations to positions which may produce a mild hypoxic stress.

Heart rate variability parameters and fetal movement complement fetal behavioral states detection via magnetography to monitor neurovegetative development.

Fetal behavioral states are defined by fetal movement and heart rate variability (HRV). At 32 weeks of gestational age (GA) the distinction of four fetal behavioral states represented by combinations of quiet or active sleep or awakeness is possible. Prior to 32 weeks, only periods of fetal activity and quiesence can be distinguished. The increasing synchronization of fetal movement and HRV reflects the development of the autonomic nervous system (ANS) control. Fetal magnetocardiography (fMCG) detects fetal heart activity at high temporal resolution, enabling the calculation of HRV parameters. This study combined the criteria of fetal movement with the HRV analysis to complete the criteria for fetal state detection. HRV parameters were calculated including the standard deviation of the normal-to-normal R–R interval (SDNN), the mean square of successive differences of the R–R intervals (RMSSD, SDNN/RMSSD ratio, and permutation entropy (PE) to gain information about the developing influence of the ANS within each fetal state. In this study, 55 magnetocardiograms from healthy fetuses of 24–41 weeks’ GA were recorded for up to 45 min using a fetal biomagnetometer. Fetal states were classified based on HRV and movement detection. HRV parameters were calculated for each state. Before GA 32 weeks, 58.4% quiescence and 41.6% activity cycles were observed. Later, 24% quiet sleep state (1F), 65.4% active sleep state (2F), and 10.6% active awake state (4F) were observed. SDNN increased over gestation. Changes of HRV parameters between the fetal behavioral states, especially between 1F and 4F, were statistically significant. Increasing fetal activity was confirmed by a decrease in PE complexity measures. The fHRV parameters support the differentiation between states and indicate the development of autonomous nervous control of heart rate function.

New Rare‐Earth Metal Germanides RE2Ge9 (RE = Nd, Sm) by Thermal Decomposition of High‐Pressure Phases REGe5

AbstractThe rare‐earth metal germanides RE2Ge9 (RE = Nd, Sm) have been prepared by thermal decomposition of the metastable high‐pressure phases REGe5 at ambient pressure. The compounds adopt an orthorhombic unit cell with a = 396.34(4) pm; b = 954.05(8) pm and c = 1238.4(1) pm for Nd2Ge9 and a = 395.46(7) pm; b = 946.4(2) pm and c = 1232.1(3) pm for Sm2Ge9. Crystal structure refinements reveal space group Pmmn (No. 59) for Nd2Ge9. The atomic pattern resembles an ordered defect variety of the pentagermanide motif REGe5 (RE = La; Nd, Sm, Gd, Tb) comprising corrugated germanium layers. These condense into a three‐dimensional network interconnected by eight‐coordinated germanium atoms. The resulting framework channels along [100] enclose the neodymium atoms. With respect to the atomic arrangement of the pentagermanides, half of the interlayer germanium atoms are eliminated in an ordered way so that occupied and empty germanium columns alternate along [001]. The rare‐earth metal atoms of both types of compounds, REGe5 and RE2Ge9, exhibit the electronic states 4f 3 and 4f 5 (oxidation state +3) for neodymium and samarium, respectively, evidencing that the modification of the germanium network leaves the electron configuration of the metal atoms unaffected.

Crystal growth and spectroscopic characterization of Yb-doped and Yb, Na-codoped PbF 2 laser crystals

High-quality pure PbF 2, Yb:PbF 2 and Yb, Na:PbF 2 crystals are grown by the Bridgman method in a nonvacuum atmosphere. Room-temperature absorption, photoluminescence spectra, and fluorescence lifetimes belonging to the transitions between ground state 2F 7/2 and the excited state 2F 5/2 of Yb 3+ ions in these crystals have been investigated. The influence of codoping with Na + ions on the spectra has been studied. Experimental results show that codoping Na + ions in different Na:Yb ratios can modulate the spectroscopy and photoluminescence properties of Yb 3+ ions in a PbF 2 lattice in a large scope: the Na + ions codoping with Yb 3+ as charge compensators can suppress the deoxidization of Yb 3+ to Yb 2+, enhance the luminescence intensity and lengthen luminescence lifetime of Yb 3+ ions.

Electroluminescence from Er and Yb co-doped silicon dioxide layers: The excitation mechanism

The excitation mechanism of photo- (PL) and electroluminescence (EL) of erbium ions co-implanted with ytterbium into the SiO 2 layer of light emitting MOS devices (MOSLED) was investigated. Ytterbium implanted and annealed samples exhibit the blue and near infrared electroluminescence. The blue electroluminescence at 470 nm appears due to cooperative up-conversion emission in the Yb 3+–Yb 3+ system, and the near infrared EL at 975 and 1025 nm corresponds to transitions from the multiple state 2F 5/2 to the 2F 7/2 ground state in the Yb 3+ ions. The Er implanted SiO 2 exhibits the luminescence in the blue-green and infrared region. The green and blue peaks correspond to radiative transitions from the 2H 11/2 or 4S 3/2 energy levels and from the 2H 9/2 or 4F 5/2 energy levels to the 4I 15/2 ground state, respectively. We have found that the energy transfer from Yb 3+ to Er 3+ ions exists only during photoluminescence excitation. The electroluminescence investigation shows the cooperative up-conversion in the Er 3+–Yb 3+ system.

Energy levels in Ag-like (4d 104f, 4d 105ℓ (ℓ = 0–3)), Pd-like (4d 94f [ J = 1], 4d 95p [ J = 1], 4d 95f [ J = 1]), and Rh-like (4d 9 [ J = 5/2, 3/2]) ions with Z ⩽ 86

Relativistic perturbation theory with a model potential is used for the calculation of energy levels of the states 4f 5/2, 4f 7/2, 5s 1/2, 5p 1/2, 5p 3/2, 5d 3/2, 5d 5/2, 5f 5/2, and 5f 7/2 above the 1s 22s 22p 63s 23p 63d 104s 24p 64d 10 core, with one vacancy 4 d 5 / 2 9 , 4 d 7 / 2 9 in the same core, in the silver and rhodium isoelectronic sequences with the maximum nuclear charge Z = 86. The method of extrapolation of the model potential parameter is applied to calculate one-electron and one-vacancy wavefunctions. The wavefunctions of Ag- and Rh-like ions were used to calculate the energies of resonance transitions to the ground state 1S 0 in Pd-like ions. Good agreement between the theoretical and the experimental energies of the resonance transitions in Pd-like ions indicates the reliability of the results obtained.

Heart rate features in fetal behavioural states

Background and aim Fetal behavioural states have been defined on the basis of eye movements, body movements and heart rate patterns as presented by cardiotocography (CTG). The aim of this work was to determine whether behavioural states can be distinguished on the basis of heart rate features alone using high resolution beat-to-beat fetal magnetocardiography. Study design Five minute magnetocardiograms were recorded at a sampling rate of 1 kHz in 40 healthy fetuses (36th–41st week of gestation). In the reconstructed RR interval time series, 256-beat epochs corresponding to the behavioural states 1F, 2F and 4F were visually identified according to heart rate patterns as defined for CTG. These epochs were then quantified using mean RR interval, its standard deviation (SDNN), its root mean square of successive difference (RMSSD) and on the basis of symbolic dynamics of short 8 beat trains. Results Pairwise comparison between the behavioural states showed that the values of each of these measures differed significantly between the states. Quadratic discriminant analysis further revealed that mean RR interval and SDNN sufficed to classify state with a correct classification of 92%. Conclusions The results suggest that measures that quantify overall aspects of heart rate can distinguish RR interval time series which were classified into different fetal behavioural states. The differences in short-term variability as quantified by RMSSD and symbolic dynamics may help reveal new aspects of these states.

Local microstructure and photoluminescence of Er-doped 12CaO·7Al 2O 3 powder

Er-doped 12CaO·7Al 2O 3 (C12A7:Er) powders were prepared using the sol-gel method followed by annealing inorganic precursors. X-ray diffraction (XRD), Raman and absorption spectra revealed that Er ions existed and substituted Ca 2+ lattice site in C12A7. The photoluminescence of C12A7:Er at room temperature was observed in the visible and infrared region using 488 nm (2.54 eV) Ar + line as excitation source, respectively. The sharp and intense green emission bands with multi-peaks around 520 nm and 550 nm correspond to the transitions from the excited states 2H 11/2 and 4S 3/2 to the ground state 4I 15/2, respectively. Furthermore, red emission band around 650 nm was also observed. It was attributed to the electronic transition from excited states 4F 9/2 to the ground state 4I 15/2 inside 4f-shell of Er 3+ ions. The intensive infrared emission at 1.54 μm was attributed to the transition from the first excited states of 4I 13/2 to the ground state ( 4I 15/2). The temperature dependent photoluminescence of infrared emission showed that the integrated intensity reached a maximum value at near room temperature. The forbidden transitions of intra-4f shell electrons in free Er 3+ ions were allowed in C12A7 owing to lack of the inversion symmetry in the Er 3+ position in C12A7 crystal field. Our results suggested that C12A7:Er was a candidate for applications in Er-doped laser materials, and full color display.

Classification and evaluation of fetal behavior with actocardiogram

Objectives. The aim was to classify fetal behavioral states by the actocardiogram (ACG).Methods. The duration of fetal movement burst was manually measured on the ACG where fetal heart rate (FHR) and movement bursts were recorded on a single chart. The occupancy and frequency of movement bursts among five new ACG parameters were determined in the classification of four behavioral ACG states. The ACG states were compared to the 1F–4F states of Nijhuis's classification of fetal behavior. Fourteen cases of active states of normal pregnancy at 28–38 weeks of gestation and five records of decreased movement bursts were studied. The ACG movement spikes were analyzed at 26–41 weeks of pregnancy using an automated program for the diagnosis of fetal states.Results and conclusion. No fetal movement burst was recorded in fetal resting state of ACG, where occupancy and frequency were zero. The burst was frequent, occupancy was 32.67 ± 14.76% and frequency was 0.647 ± 0.212 cycles per minute (cpm) in the active ACG states. The longest burst duration was 5 min and accompanied by transient tachycardia in highly active states. Therefore, fetal resting ACG state was comparable to 1F, active ACG state 2F and highly active ACG state 4F states. The movement bursts were sporadic in the five cases of decreased movement, where the occupancy was less than 8% and frequency was 0.2 or less cpm. The five particular cases were classified as intermediate ACG state, and they were comparable to the 3F state. Active, resting and intermediate states were also determined by automated analysis of movement spikes. From these results, fetal behavioral states would be classified by ACG with similar utility to conventional classification.

Permutation entropy improves fetal behavioural state classification based on heart rate analysis from biomagnetic recordings in near term fetuses

The relevance of the complexity of fetal heart rate fluctuations with regard to the classification of fetal behavioural states has not been satisfyingly clarified so far. Because of the short behavioural states, the permutation entropy provides an advantageous complexity estimation leading to the Kullback-Leibler entropy (KLE). We test the hypothesis that parameters derived from KLE can improve the classification of fetal behaviour states based on classical heart rate fluctuation parameters (SDNN, RMSSD, ln(LF), ln(HF)). From measured heartbeat sequences (35 healthy fetuses at a gestational age between 35 and 40 completed weeks) representative intervals of 256 heartbeats were visually preclassified into fetal behavioural states. Employing discriminant analysis to separate the states 1F, 2F and 4F, the best classification result by classical parameters was 80.0% (SDNN). After additionally considering KLE parameters it was improved significantly (p<0.0005) to 94.3% (ln(LF), KLE_Mean). It could be confirmed that KLE can improve the state classification. This might reflect the consideration of different physiological aspects by classical and complexity measures.

Studies on blue and red photoluminescence from Al 2O 3:Ce 3+:Mn 2+coatings synthesized by spray pyrolysis technique

Al 2O 3:Ce 3+:Mn 2+ films deposited by the spray pyrolysis technique show blue and red emissions under ultraviolet light excitation. The blue emission is due to the de-excitation of Ce 3+ ions from their excited state 5d to the split ground state 2F. The usually weak red emission attributed to 3d→3d de-excitation of Mn 2+ is enhanced through an efficient energy transfer from Ce 3+ to Mn 2+ ions. The quantum efficiency of this transfer is near to 100%. SEM and RBS have been used to analyze the surface morphology and chemical composition of Ce- and Mn-doped Al 2O 3 films. The films were also characterized by the X-ray photoelectron spectroscopy technique, and it was found that a considerable amount of Mn ions remains linked to chlorine while Ce is mostly in an oxidized state.

Vibroacoustic stimulation in normal term human pregnancy

Objective To examine the effects of vibroacoustic stimulation (VAS) on fetal heart rate (FHR) in term human fetuses by computerized carditocography system. Methods FHR was analyzed 20 min before and 30 min after vibroacoustic stimulation using the Oxford Sonicaid System 8002 for computerized FHR measurement. Recordings were made in 31 uncomplicated pregnancies at 36–42 weeks' gestation. Results Vibroacustic stimulation of the fetus evoked a significant increase in all the parameters evaluated (number of fetal movements, of accelerations above 10 and 15 bpm, in high- and low-variability episodes, and in short-term variations). Concerning the effect of behavioural states on the response to VAS, some changes (FHR, high-variability episodes) occurred independently of behavioural states, while other parameters (accelerations >10 and 15 bpm: short-term variation) underwent statistically significant changes only for behavioural states 1F and 2F. Conclusions Our study supports the hypothesis of a significant fetal response in normal term pregnancy, as clearly shown by computerized cardiotocography. The immediate response occurred independently of behavioural states, although some differences were present (mainly for F1 and F2 states) if the evaluation was extended in time.

Umbilical venous volume flow and fetal behavioral states in the normally developing fetus

To determine the relationship between umbilical venous (UV) volume flow and fetal behavioral states 1F (quiet sleep) and 2F (active sleep) in normal pregnancies at 36-40 weeks of gestation. Fetal behavioral states were established in 17 normal pregnancies by means of combined assessment of fetal heart rate patterns (FHRP), and fetal eye and body movements. UV vessel area (mm(2)) as obtained by tracing the inner vessel area using Labview and Imaq Vision software and UV time-averaged flow velocity (mm/s Doppler) were multiplied to calculate UV volume flow (mL/min) including flow/kg fetus. The pulsatility index (PI) in the umbilical artery was also determined. In each woman, all parameters were measured between three and five times in each behavioral state. Data are reported as mean +/- 1 SD and analyzed by paired t-test. No statistically significant behavioral-state-related changes were observed for UV time-averaged velocity and UV volume flow, resulting in UV volume flow/kg fetus of 69.1 +/- 14.9 mL/min*kg at 1F and 71.6 +/- 12.1 mL/min*kg at 2F (not significant). A statistically significant increase (P = 0.02) was established for UV cross-sectional area (46.4 +/- 8.6 mm(2) vs. 49.0 +/- 10.1 mm(2)) and for fetal heart rate (FHR) from 134.2 +/- 10.3 bpm in 1F to 144.2 +/- 7 bpm in 2F. Umbilical artery PI was not significantly different between the two behavioral states. On the basis of high venous vessel wall compliance, the significant increase in UV cross-sectional area during fetal behavioral state 2F may be determined by a rise in mean venous pressure. The significant rise in FHR may reflect increased fetal cardiac output during state 2F while the resistance at the hepato-ductal pathway remains relatively constant with the purpose of meeting raised energy demands during the active sleep state. This is further supported by the observed trend towards an increase in UV volume flow.

Evaluación neurológica del feto

To review recent advances in the procedures and techniques that have made possible to evaluate the anatomy and function of the central nervous system (CNS) in the fetus. The neurological evaluation of the fetus can be performed at different levels: clinical, anatomical and functional. At a clinical level the analysis of body, ocular or respiratory fetal movements, as well as fetal heart rate, defines 4 behavioural states: 1F and 2F correspond to the quiet and active sleep, respectively. States 3F and 4F occur during wakefulness in the newborn, but there is no scientific evidence that the fetus is awake. Behavioral states probably play an important role in the process of CNS maturation and development. Anatomic evaluation of the CNS to rule out brain malformations can be performed with ultrasound since week 7-8 of gestational age and with magnetic resonance imaging (MRI) since week 18-20. Both techniques are also useful in the diagnosis of acquired fetal neurological diseases. Both modalities are concordant in the majority of cases, but in others each of them provides additional, different information. Computed tomography should only be used in selected cases that involve bone structures. Functional evaluation of fetal CNS can be performed with proton MR spectroscopy, which determines the cerebral content of inositol, choline, creatine and N-acetylaspartate. Other techniques to functionally study the fetal brain are functional MRI (fMRI), near infrared spectroscopy, and magnetoencephalography. Fetal neurology is a discipline that will continue to develop fast in the immediate future. Technological advances will facilitate the possibility of a more rapid and reliable diagnosis of anatomic or functional abnormalities of the fetal CNS.