We focus here on the summaries in french of the internal reports published by INRIA from 1989 to 1998. Our goal is to study the scientific topics of the reports, to bring on the fore a typology of the themes. For that, we use factorial correspondence analysis and the software QNOMIS II which lets us to visualize the results in a friendly way. We can say that the first analyses allow us first to evaluate the quality of the database, then to give some comments about the topics of the reports related to the research themes of the institute. The study is still in process and should be finished in a few weeks.

The objective of this paper is to evaluate the robustness of biometric approaches based on human ECG signals. Two questions are addressed: is it required to record the ECG in supine rest as it is classically performed? Is it necessary to compare only shapes recorded in the same condition? A 12-lead ECG, from 14 normal subjects, in three experimental conditions (supine rest, standing and exercise), has been recorded. An analysis based on the computation of the Discrimination Coefficient (DC) between intra-and inter-subjects shows that comparing shapes recorded in the same condition leads to similar values of DC for the three conditions, provided that the interval length is lower than 800 ms. Merging the conditions leads to values of DC always greater than 1 provided that the interval length is lower than 600 ms. A clustering approach, based on correspondence analysis and hierarchical ascending classification, shows that, when merging the conditions, the ECG of a subject are in the same cluster in 94% of the cases.

The aim of the present study was to evidence that the heart reinnervation can occur and it is related with the time after transplantation (evolution with time). Data were evaluated using Multiple Correspondence Analyses (MCA), which is the ideal method to study the relation, probably nonlinear, between the Time After Transplantation (TAT) and the probable restoration of normal heart rate responses of sinus node that's regulated by the autonomic nervous system. Twenty four nonrejecting transplant recipients (60 ± 48 months after transplantation) and nine healthy subjects were studied by heart rate variability parameters. Results showed that sympathetic activity is restored some time after transplantation. Until 48 months, the recent HTR are in direct correlation to low values SD and LF and for the oldest transplant recipient, these parameters are similar to that observed in normal subjects.

BACKGROUND In this prospective observational study, we aim to explore the relationship between age and bispectral index (BIS) values at different plasma concentrations of propofol. METHODS Fifty children aged from 3 to 15 yr were included. Anaesthesia was induced using a target-controlled infusion of propofol with the Kataria pharmacokinetic model together with a bolus of remifentanil followed by a continuous infusion rate at 0.2 microg kg(-1) min(-1). Target plasma propofol concentration was initially stabilized to 6 microg ml(-1) and continued for 6 min. The target was then decreased and stabilized to 4 microg ml(-1) and then to 2 microg ml(-1). BIS values, plasma propofol concentration, and EEG were continuously recorded. In order to explore the relationship between variations in propofol concentration and the EEG bispectrum, we used a multiple correspondence analysis (MCA). Results are shown in median (range). RESULTS We found no statistical difference between BIS values with propofol 6 microg ml(-1) [23 (12-40)] and 4 microg ml(-1) [28 (9-67)]. At 2 microg ml(-1), BIS was significantly different [52 (24-71)], but a significant correlation between the age of children and BIS values was found (r2=0.66; P<0.01). There was little change in children's position between 6 and 4 microg ml(-1) in the structure model of the MCA. From 4 to 2 microg ml(-1), the position of children moved only on axis 2. CONCLUSIONS These results showed the difficulty to interpret BIS values because of the absence of significant change for higher plasma propofol concentration variation or because of the link with age for the lower plasma concentration.

Quelle est l’importance dans la variabilité à très court terme en SRM cérébrale 1H simple volume (SV) de variations individuelles, et régionales d’aire, d’amplitude ou de profil spectral chez des volontaires sains (VS) ? SRM : 1H SV STEAM court TE (après IRM) pour étude de reproductibilité à très court terme, sur 2 appareils d’IRM 1,5T chez 12 VS dans 2 à 5 régions anatomiques. Traitements des données : logiciel SA/GE (GEMS) calculant amplitudes, aires et concentrations relatives. Analyse statistique : comparaison de moyennes et CVs ; Analyse Factorielle de Correspondance (AFC) et Classification Ascendante Hiérarchique (CAH) de groupes de profils spectraux. Dans le cerveau la variabilité est plus importante que dans un objet test et dépend du métabolite, de la variabilité intra et inter sujet et de la région anatomique. Des régions et des métabolites sont plus reproductibles que d’autres. L’AFC et la CAH séparent 5 groupes de profils spectraux. Les relations entre ces profils et les régions furent étudiées. Les variations instrumentales peuvent être peu élevées même dans des régions réputées difficiles. L’importance des différences régionales et des variations individuelles est à considérer pour les comparer aux variations de processus pathologiques.

BACKGROUNDThe relationship between end-tidal sevoflurane concentration, bispectral index (BIS) and the EEG bispectrum in children appears to be age dependent. The aim of this study was to quantify the BIS values at 1 MAC (minimum alveolar concentration) for desflurane and halothane, and explore the relationship with age for these anaesthetic agents in children.METHODSECG, EEG and BIS were recorded continuously in 90 children aged 6-170 months requiring anaesthesia for elective surgery. Fifty children were anaesthetized with desflurane, and 40 children with halothane. Recordings were performed through to a steady state of 2 MAC, and thereafter at 1 and 0.5 MAC, respectively. The bispectrum of the EEG was estimated using MATLAB(c) software. A multiple correspondence analysis (MCA) was used.RESULTSAt a steady state of 1 MAC, BIS values were significantly higher with halothane 62 (43-80) than desflurane 34 (18-64). BIS values were significantly correlated with age in both groups: DES (r(2)=0.57; P<0.01) and HALO (r(2)=0.48; P<0.01). Changes in position in the structured model of the MCA (dependent on the pattern of the EEG bispectrum) were different for the two volatile anaesthetic agents.CONCLUSIONSIn children, BIS values are linked to age irrespective of the volatile anaesthetic agent used. The difference in BIS values for different agents at the same MAC can be explained by the specific effect on the EEG bispectrum induced by each anaesthetic agent, bringing into question the ability of the EEG bispectrum to accurately determine the depth of anaesthesia.

Remifentanil can cause bradycardia either by parasympathetic activation or by other negative chronotropic effects. The high frequency (HF) component of heart rate variability (HRV) is a marker of parasympathetic activity. This study aimed to evaluate the effect of remifentanil on RR interval and on HRV in children. Forty children ASA I or II were studied after approval by the human studies committee and informed parental consent was obtained. After stabilisation at sevoflurane 1 MAC, they were randomly divided into two groups: one received a 20 μg.kg −1 atropine injection (AT + REMI) and the other ringer lactate solution (REMI). Three minutes later, a 1 μg.kg −1 bolus of remifentanil was administered over 1 min, followed by a continual infusion at 0.25 μg.kg −1 .min −1 for 10 min increased to 0.5 μg.kg −1 .min −1 for a further 10 min. A time varying, autoregressive analysis of RR sequences was used to estimate classical spectral parameters: low (0.04–0.15 Hz; LF) and high (0.15–0.45 Hz; HF) frequency, whereas the root mean square of successive differences of RR intervals (rmssd) was derived directly from the temporal sequence. Statistical analyses were conducted by means of the multiple correspondence analysis and with non parametrical tests. Remifentanil induced an RR interval lengthening, i.e. bradycardia, in both groups compared to pretreatment values and was associated with an increase of HF and rmssd only for the REMI group. The parasympathetic inhibition by atropine did not totally prevent remifentanil's negative chronotropic effect. A direct negative chronotropic effect of remifentanil is proposed.

Déterminer en SRM cérébrale (1H, simple volume, court TE) les variations spectrales en fonction de la région anatomique, du type tissulaire ou de modalités instrumentales chez 76 volontaires sains. IRM : 2D sagittales et axiales 3D T1 et 2D T2. SRM : 1H, volume de 7 à 12 cm3, STEAM (TE 30 ms) sur 2 appareils 1.5 T (GEMS) chez 76 VS (de 20 à 74 ans) dans 7 régions anatomiques. Traitements des données : logiciel SA/GE. Analyse statistique : comparaison de moyennes ; Analyse Factorielle de Correspondance (AFC) et Classification Ascendante Hiérarchique (CAH) de groupes homogènes de profils spectraux. La variabilité fonction du type tissulaire est plus élevée que la variabilité régionale, notamment pour la Choline et le N-Acétyl-Aspartate (NAA). Certaines régions et certains métabolites (comme le NAA ou la Créatine) sont moins variables. L’AFC et la CAH séparent 6 groupes homogènes de profils spectraux. La relation de chacun de ces profils avec des paramètres instrumentaux et des régions anatomiques fut étudiée. L’importance des fluctuations dues aux différences instrumentales, régionales et individuelles est essentielle à considérer pour augmenter la sensibilité et comparer ces variations à celles de processus pathologiques.

BACKGROUND:Remifentanil is known to cause bradycardia and hypotension. We aimed to characterize the haemodynamic profile of remifentanil during sevoflurane anaesthesia in children with or without atropine.METHODS:Forty children who required elective surgery received inhalational induction of anaesthesia using 8% sevoflurane. They were allocated randomly to receive either atropine, 20 microg kg(-1) (atropine group) or Ringer's lactate (control group) after 10 min of steady-state 1 MAC sevoflurane anaesthesia (baseline). Three minutes later (T0), all children received remifentanil 1 microg kg(-1) injected over a 60 s period, followed by an infusion of 0.25 microg kg(-1) min(-1) for 10 min then 0.5 microg kg(-1) min(-1) for 10 min. Haemodynamic variables and echocardiographic data were determined at baseline, T0, T5, T10, T15 and T20 min.RESULTS:Remifentanil caused a significant decrease in heart rate compared with the T0 value, which was greater at T20 than T10 in the two groups: however, the values at T10 and T20 were not significantly different from baseline in the atropine group. In comparison with T0, there was a significant fall in blood pressure in the two groups. Remifentanil caused a significant decrease in the cardiac index with or without atropine. Remifentanil did not cause variation in stroke volume (SV). In both groups, a significant increase in systemic vascular resistance occurred after administration of remifentanil. Contractility decreased significantly in the two groups, but this decrease remained moderate (between -2 and +2 sd).CONCLUSION:Remifentanil produced a fall in blood pressure and cardiac index, mainly as a result of a fall in heart rate. Although atropine was able to reduce the fall in heart rate, it did not completely prevent the reduction in cardiac index.

BACKGROUND The aim of this study was to evaluate the potential relationship between age, BIS (Aspect), and the EEG bispectrum during anaesthesia with sevoflurane. METHODS BIS and raw EEG were recorded at a steady state of 1 MAC in 100 children, and during a decrease from 2 to 0.5 MAC in a sub-group of 29 children. The bispectrum of the EEG was estimated using MATLAB software. For analysis, the bispectrum was divided into 36 frequencies of coupling (P(i))--the MatBis. A multiple correspondence analysis (MCA) was used to establish an underlying structure of the pattern of each individual's MatBis at 1 MAC. Clustering of children into homogeneous groups was conducted by a hierarchical ascending classification (HAC). The level of statistical significance was set at 0.05. RESULTS At 1 MAC, the BIS values for all children ranged from 20 to 74 (median 40). Projection of both age and BIS value recorded at 1 MAC onto the structured model of the MCA showed them to be distributed along the same axis, demonstrating that the different values of BIS obtained in younger or older children are mainly dependent on their MatBis. At 1 MAC, six homogeneous groups of children were obtained through the HAC. Groups 5 (30 months; range 23-49) and 6 (18 months; range 6-180) were the younger children and Group 1 (97 months; range 46-162) the older. Groups 5 and 6 had the highest median values of BIS (54; range 50-59) (55; range 26-74) and Group 1 the lowest values (29; range 22-37). CONCLUSION The EEG bispectrum, as well as the BIS appeared to be strongly related to the age of children at 1 MAC sevoflurane.

Background and Objectives: During regional anesthesia, various stimuli leading to an adrenergic response can occur. However, simulation of an epidural test dose by using intravenous administration of epinephrine (EPI) has always been compared with an intravenous saline infusion as the control. The aim of this study was to evaluate the possibility of distinguishing in children the effect on HR by an intravascular epinephrine infusion and a painful stimulus, using heart rate variability (HRV) and beat-to-beat analysis of HR.Methods: Thirty American Society of Anesthesiologists physical status P I children who required elective surgery were studied. At I minimum alveolar concentration (MAC) of sevoflurane, electrocardiogram was recorded continuously. Systolic blood pressure (SBP) was measured every minute. Measurements were performed after an intravenous administration of 0.5 mug/kg of epinephrine and during a small skin surgical incision (SI). Time-varying auto-regressive modeling of the interpolated RR sequences was performed for estimating power spectrum (msec(2)). The HF bands were defined by (0.15-0.4 Hz).Results: Median (range) age and weight of all children were 3.5 (1-10) years and 16 (9-30) kg. EPI produced a lower increase in HR than did SI. SBP increased significantly more than did after SI. T-wave amplitude increased significantly after EPI but not after SI. Sixty seconds after the first change in HR, a secondary decrease (in comparison to control value) can be detected with EPI in contrast to SI. HF spectral power increased significantly after EPI administration but decreased after SI. The sensitivity, specificity, and positive and negative predictive value were respectively for DeltaHR >10 beats per minute of 56%, 26%, 43%, and 38%; for DeltaSBP >15 mm Hg of 60%, 86%, 81%, and 67%; and for DeltaT-wave amplitude >25% of 86%, 73%, 76%, and 84%. Using detection of the secondary decrease of HR, 60 seconds after the first change in HR, sensitivity, specificity, and positive and a negative predictive value were respectively 96%, 100%, 100%, and 96%.Conclusions: Detection of the secondary HR decrease, 60 seconds after the first change in HR, allows us to distinguish the effects of a painful stimulus from those related to the epinephrine test dose at I MAC of sevoflurane. This secondary HR decrease induced by epinephrine appears primarily because of a compensatory increase in parasympathetic tone.