On-line apnea-bradycardia detection using hidden semi-Markov models.

International audienceIn this work, we propose a detection method that exploits not only the instantaneous values, but also the intrinsic dynamics of the RR series, for the detection of apnea-bradycardia episodes in preterm infants. A hidden semi-Markov model is proposed to represent and characterize the temporal evolution of observed RR series and different pre-processing methods of these series are investigated. This approach is quantitatively evaluated through synthetic and real signals, the latter being acquired in neonatal intensive care units (NICU). Compared to two conventional detectors used in NICU our best detector shows an improvement of around 13% in sensitivity and 7% in specificity. Furthermore, a reduced detection delay of approximately 3 seconds is obtained with respect to conventional detectors

The Digi-NewB project for preterm infant sepsis risk and maturity analysis

It is known from the literature that the careful analysis of the heart rate variability of a preterm infant can be used as a predictor of sepsis. The Digi-NewB project aims at collecting a database of at least 750 preterm infants including physiological signals, video and clinical observations. These data are used to design a decision support system for the early detection of sepsis and for the evaluation of the infant maturity. The preparation of the data for the exploratory analysis has turned out to be time-consuming. 190 infants have been recorded by March 2018 and of these, the R-R interval analysis of the ECG signals has been completed of 136 infants. The results of the project are still preliminary but seven heart rate variability parameters have been found to be different in preterm and full-term infants with a P value less than 0.01. The video analysis algorithm detecting the presence of personnel or relatives reached 96.8% of sensitivity and 95.1% of specificity.It is known from the literature that the careful analysis of the heart rate variability of a preterm infant can be used as a predictor of sepsis. The Digi-NewB project aims at collecting a database of at least 750 preterm infants including physiological signals, video and clinical observations. These data are used to design a decision support system for the early detection of sepsis and for the evaluation of the infant maturity. The preparation of the data for the exploratory analysis has turned out to be time-consuming. 190 infants have been recorded by March 2018 and of these, the R-R interval analysis of the ECG signals has been completed of 136 infants. The results of the project are still preliminary but seven heart rate variability parameters have been found to be different in preterm and full-term infants with a P value less than 0.01. The video analysis algorithm detecting the presence of personnel or relatives reached 96.8% of sensitivity and 95.1% of specificity

Time-frequency relationships between heart rate and respiration: A diagnosis tool for late onset sepsis in sick premature infants

International audienceThe diagnosis of late onset sepsis in premature infants remains difficult because clinical signs are subtle and non-specific and none of the laboratory tests, including CRP and blood culture, have high predictive accuracy. Heart rate variability (HRV) analysis emerges as a promising diagnostic tool. Entropy and long-range fractal correlation are decreased in premature infants with proven sepsis. Besides this, respiration and its relations to HRV appear to be less. The objective of this study was to determine if analysis of time-frequency correlations between the heart rate and respiration amplitude may help for the diagnosis of infection in premature infants. An estimator of the linear relationship between nonstationary signals, recently introduced, is explored. The tests were performed on a cohort study of 60 premature infants. The results show that the correlation in the low frequency band tended to be higher in the sepsis group

A review of the use of optimal transport distances for high resolution seismic imaging based on the full waveform

We consider the high-resolution seismic imaging method called full-waveform inversion (FWI). FWI is a data fitting method aimed at inverting for subsurface mechanical parameters. Despite the large adoption of FWI by the academic and industrial communities, and many successful results, FWI still suffers from severe limitations. From a mathematical standpoint, FWI is a large scale PDE-constrained optimization problem. The misfit function that is used, which measures the discrepancy between observed seismic data and data calculated through the solution of a wave propagation problem, is non-convex. After discretization, the size of the FWI problem requires the use of local optimization solvers, which are prone to converge towards local minima. Thus the success of FWI strongly depends on the choice of the initial model to ensure the convergence towards the global minimum of the misfit function. This limitation has been the motivation for a large variety of strategies. Among the different methods that have been investigated, the use of optimal transport (OT) distances-based misfit functions has been recently promoted. The leading idea is to benefit from the inherent convexity of OT distances with respect to dilation and translation to render the FWI problem more convex. However, the application of OT distances in the framework of FWI is not straightforward, as seismic data is signed, while OT has been developed for the comparison of probability measures. The purpose of this study is to review two methods that were developed to overcome this difficulty. Both have been successfully applied to field data in an industrial framework. Both make it possible to better exploit the seismic data, alleviating the sensitivity to the initial model and to various conventional workflow steps, and reducing the uncertainty attached to the subsurface mechanical parameters inversion.Comment: 18 figure

A model-based approach for the evaluation of vagal and sympathetic activities in a newborn lamb.

International audienceThis paper proposes a baroreflex model and a recursive identification method to estimate the time-varying vagal and sympathetic contributions to heart rate variability during autonomic maneuvers. The baroreflex model includes baroreceptors, cardiovascular control center, parasympathetic and sympathetic pathways. The gains of the global afferent sympathetic and vagal pathways are identified recursively. The method has been validated on data from newborn lambs, which have been acquired during the application of an autonomic maneuver, without medication and under beta-blockers. Results show a close match between experimental and simulated signals under both conditions. The vagal and sympathetic contributions have been simulated and, as expected, it is possible to observe different baroreflex responses under beta-blockers compared to baseline conditions

Caesarean section at term: the relationship between neonatal respiratory morbidity and microviscosity in amniotic fluid.

None of the authors report any conflicts of interest.International audienceOBJECTIVES: The incidence of neonatal respiratory morbidity following an elective caesarean section is 2-3 times higher than after a vaginal delivery. The microviscosity of surfactant phospholipids, as measured with fluorescence polarisation, is linked with the functional characteristics of fetal surfactant and thus fetal lung maturity, but so far this point has received little attention in new-borns at term. The aim of the study is to evaluate the correlation between neonatal respiratory morbidity and amniotic microviscosity (Fluorescence Polarisation Index) in women undergoing caesarean section after 37 weeks' gestation. STUDY DESIGN: The files of 136 women who had undergone amniotic microviscosity studies during elective caesarean deliveries at term were anonymised. Amniotic fluid immaturity (AFI) was defined as a Fluorescence Polarisation Index higher than 0.335. RESULTS: Respiratory morbidity was observed in 10 babies (7.3%) and was independently associated with AFI (OR: 6.11 [95% CI, 1.20-31.1] with p=0.029) and maternal body mass index (OR: 1.12 [95% CI, 1.02-1.22] with p=0.019). Gestational age at the time of caesarean delivery was inversely associated with AFI (odds ratio, 0.46 [95% confidence interval, 0.29-0.71], p<0.001), especially before 39 weeks, and female gender was associated with an increased risk (odds ratio, 3.29 [95% confidence interval, 1.48-7.31], p=0.004). CONCLUSIONS: AFI assessed by amniotic microviscosity was significantly associated with respiratory morbidity and independently correlated with shorter gestational age especially before 39 weeks. This finding provides a physiological rationale for recommending delaying elective caesarean section delivery until 39 weeks of gestation to decrease the risk for respiratory morbidity

Wild-type VHL Clear Cell Renal Cell Carcinomas Are a Distinct Clinical and Histologic Entity: A 10-Year Follow-up

International audienceBackground: Clear cell renal cell carcinoma (ccRCC) is an aggressive tumor with 50% risk of metastases at initial diagnosis or at follow-up. An inactivation of the tumor-suppressor gene von Hippel-Lindau (VHL) is present in &gt;70% of sporadic cases by two of three different mechanisms: locus deletion, gene mutation, or promoter hypermethylation. Objective: To correlate the complete status of the VHL gene with clinical and pathologic criteria. Design, setting, and participants We retrospectively included 98 patients with ccRCC who underwent surgery between 2002 and 2005. VHL gene deletions (71 of 98; 72.4%), mutations (68 of 98; 69.4%), and promoter hypermethylations (13 of 98; 13.3%) were screened by gene copy analysis, gene sequencing, and methylation-specific multiplex ligation-dependent probe amplification, respectively. Outcome measurements and statistical analysis Relationships between VHL subgroups and the studied criteria were analyzed using chi-square and Student t tests. Survival was analyzed with the log-rank test and Kaplan-Meier curves. Results and limitations: Compared with ccRCCs with two events (66.3%), tumors with no or one genetic event (33.6%) were associated with a higher nuclear grade IV (p = 0.02), metastases (p = 0.04), sarcomatoid component (p = 0.01), dense lymphocyte infiltrate (p = 0.013), and vascular endothelial growth factor overexpression (&gt;30%) (p = 0.003), which was also an independent factor after multivariate analysis. Furthermore, wild-type VHL tumors (no inactivating event, 11.2%) were associated with nodal involvement (p = 0.019), and patients with this type of tumor had a specific survival of 33 mo compared with patients with ccRCCs having one or two VHL inactivating events (107 mo; p = 0.016). The retrospective design with small number of wild-type tumors was a limitation of this work. Conclusions: This long-term study (10-yr clinical follow-up) confirms that ccRCCs with wild-type VHL are highly aggressive tumors that need to be formally identified. Patient summary Among activated VHL tumors, the wild-type subgroup defines an aggressive phenotype with worse survival rates, suggesting that these tumors must be more thoroughly screene

Glucocorticoid Effects on the Programming of AT1b Angiotensin Receptor Gene Methylation and Expression in the Rat

Adverse events in pregnancy may ‘programme’ offspring for the later development of cardiovascular disease and hypertension. Previously, using a rodent model of programmed hypertension we have demonstrated the role of the renin-angiotensin system in this process. More recently we showed that a maternal low protein diet resulted in undermethylation of the At1b angiotensin receptor promoter and the early overexpression of this gene in the adrenal of offspring. Here, we investigate the hypothesis that maternal glucocorticoid modulates this effect on fetal DNA methylation and gene expression. We investigated whether treatment of rat dams with the 11β-hydroxylase inhibitor metyrapone, could prevent the epigenetic and gene expression changes we observed. Offspring of mothers subjected to a low protein diet in pregnancy showed reduced adrenal Agtr1b methylation and increased adrenal gene expression as we observed previously. Treatment of mothers with metyrapone for the first 14 days of pregnancy reversed these changes and prevented the appearance of hypertension in the offspring at 4 weeks of age. As a control for non-specific effects of programmed hypertension we studied offspring of mothers treated with dexamethasone from day 15 of pregnancy and showed that, whilst they had raised blood pressure, they failed to show any evidence of Agtr1b methylation or increase in gene expression. We conclude that maternal glucocorticoid in early pregnancy may induce changes in methylation and expression of the Agtr1b gene as these are clearly reversed by an 11 beta-hydroxylase inhibitor. However in later pregnancy a converse effect with dexamethasone could not be demonstrated and this may reflect either an alternative mechanism of this glucocorticoid or a stage-specific influence