A scalable high-performance magnetic shield for very long baseline atom interferometry.

We report on the design, construction, and characterization of a 10 m-long high-performance magnetic shield for very long baseline atom interferometry. We achieve residual fields below 4 nT and longitudinal inhomogeneities below 2.5 nT/m over 8 m along the longitudinal direction. Our modular design can be extended to longer baselines without compromising the shielding performance. Such a setup constrains biases associated with magnetic field gradients to the sub-pm/s2 level in atomic matterwave accelerometry with rubidium atoms and paves the way toward tests of the universality of free fall with atomic test masses beyond the 10-13 level.

Effect of Pure Dephasing and Phonon Scattering on the Coupling of Semiconductor Quantum Dots to Optical Cavities.

Using site-controlled semiconductor quantum dots (QDs) free of multiexcitonic continuum states, integrated with photonic crystal membrane cavities, we clarify the effects of pure dephasing and phonon scattering on exciton-cavity coupling in the weak-coupling regime. In particular, the observed QD-cavity copolarization and cavity mode feeding versus QD-cavity detuning are explained quantitatively by a model of a two-level system embedded in a solid-state environment.

[Paediatric discharge score in ambulatory surgery]. / Score de sortie pédiatrique en chirurgie ambulatoire.

BACKGROUND: In adults, the Post-Anesthetic Discharge Scoring System (PADSS) was built to secure the discharge after outpatient surgery. We evaluate a pediatric adaptation: the Pediatric-PADSS (Ped-PADSS). STUDY DESIGN: Prospective cohort. METHODS: This was a prospective, observational, monocentric study for ambulatory patients. Ped-PADSS is built on 5 items each quoted 0, 1, or 2: hemodynamics, state of awakening, nausea/vomiting, pain and bleeding. A result ≥9/10 validated discharge if the anesthetist did not wish to review the patient, if the parents did not wish to revisit the anesthetist or if there was no hoarseness or dyspnea. The discharge was validated by the anesthetist and the surgeon. Ped-PADSS was made without the knowledge of the nursing team, one hour after return in service and repeated hourly. Addition of patient demographic data, the collection included the hours of leave by the anesthetist, surgeon and Ped-PADSS, the duration of hospital stay post procedure. RESULTS: On 150 patients, 148 patients were allowed to go out with the Ped-PADSS, one patient was released despite a Ped-PADSS<9. One patient was hospitalized for a surgical bleeding in agreement with the anesthetist, surgeon and the Ped-PADSS. Ninety-five percent of patients had a Ped-PADSS ≥9 after 2hours monitoring in the ambulatory unit. CONCLUSION: The majority of the children have met the criteria for discharge at the end of 2hours postoperative monitoring. The use of this score could reduce the hospitalization time in ambulatory unit.

[Ambulatory surgery in France: practical and medicolegal considerations]. / La chirurgie ambulatoire: organisation pratique et aspects médico-légaux, en France.

In France, ambulatory anaesthesia and surgery seem to be well codified. Many recommendations have been published by the Health Authority and the professional associations: they are summarized in this review. However, numerous practical problems persist: for example, two situations specific to paediatric practice are problematic parental comprehension and application of the information provided and poor access to strong analgesics outside the hospital. Despite this, the paediatric population is an ideal target for ambulatory care because of its usual good health and quicker recovery after minor injury as proven by the small percentage of failure and readmission.

[Chronic pain after cesarean: Impact and risk factors associated]. / Douleurs chroniques après césarienne: impact et facteurs de risque associés.

BACKGROUND: Chronic postoperative pain is a well-recognized problem after amputation, thoracotomy, mastectomy and inguinal hernia repair but has not been well evaluated after obstetric surgery. STUDY DESIGN: Retrospective cohort. OBJECTIVES: To determine the rate of chronic pain after cesarean, their impact on quality of life of patients and risk factors associated with this complication. METHODS: A questionnaire was sent to 220 consecutive patients who underwent caesarean delivery in a 6-month period. The questions focused on the duration of incisional pain after caesarean, severity and impact on daily activities. Meanwhile, a retrospective collection of clinical data (history, details of surgery and anaesthesia) was performed. After a descriptive analysis of the study population, a comparison of patients with and without DCPC was conducted to highlight potential risk factors. RESULTS: One hundred and sixty-seven patients (76%) completed the survey. The average response time was 10months (range 8-12) after caesarean section. The postoperative pain was resoluted in most patients within three months but persisted in 25 patients (15%). Seven patients (4%) showed a deterioration of their quality of life because of daily moderate to severe incisional pain. Risk factors associated with chronic pain were the presence of acute pain in postoperative, pre-existing pain (headaches, back pain), a young age and the achievement of general anaesthesia without locoregional associated at caesarean section. CONCLUSION: The occurrence of chronic pain after cesarean section may be frequent and can be responsible for an impaired quality of life.

[Systemic analgesia at home after pediatric day-case surgery]. / Analgésie systémique à domicile après chirurgie pédiatrique ambulatoire.

Currently, day-case surgery has a significant development. In pediatrics, a big part of interventions can be performed as a day-case surgery. However, postoperative pain, often wrongly regarded as minor, should not be underestimated or undertreated. The aim of this paper is to review the available systemic analgesics and to propose a way to use them in order to improve children's comfort and experiences in their own families.

Variation of bispectral index under TIVA with propofol in a paediatric population.

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.

Brain activity modeling in general anesthesia: enhancing local mean-field models using a slow adaptive firing rate.

In this paper, an enhanced local mean-field model that is suitable for simulating the electroencephalogram (EEG) in different depths of anesthesia is presented. The main building elements of the model (e.g., excitatory and inhibitory populations) are taken from Steyn-Ross [M. L. Steyn-Ross, Phys. Rev. E 64, 011917 (2001), D. A. Steyn-Ross, Phys. Rev. E 64, 011918 (2001)] and Bojak and Liley [I. Bojak and D. T. Liley, Phys. Rev. E 71, 041902 (2005)] mean-field models and a new slow ionic mechanism is included in the main model. Generally, in mean-field models, some sigmoid-shape functions determine firing rates of neural populations according to their mean membrane potentials. In the enhanced model, the sigmoid function corresponding to excitatory population is redefined to be also a function of the slow ionic mechanism. This modification adapts the firing rate of neural populations to slow ionic activities of the brain. When an anesthetic drug is administered, the slow mechanism may induce neural cells to alternate between two levels of activity referred to as up and down states. Basically, the frequency of up-down switching is in the delta band (0-4 Hz) and this is the main reason behind high amplitude, low frequency fluctuations of EEG signals in anesthesia. Our analyses show that the enhanced model may have different working states driven by anesthetic drug concentration. The model is settled in the up state in the waking period, it may switch to up and down states in moderate anesthesia while in deep anesthesia it remains in the down state.

Effect of epinephrine on epidural, intrathecal, and plasma pharmacokinetics of ropivacaine and bupivacaine in sheep.

BACKGROUND: Local vasoconstriction induced by epinephrine added to epidural local anaesthetics has been shown to improve their quality and duration of action in several clinical reports. There are several assumptions on the mechanisms. This study was designed to evaluate the influence of epinephrine on transmeningeal uptake of epidurally administered ropivacaine and bupivacaine by measuring local anaesthetic concentrations in the epidural and intrathecal spaces and in plasma. METHODS: Ropivacaine (50 mg) and bupivacaine (30 mg) were administered epidurally in sheep with and without epinephrine (75 microg). A microdialysis technique was used to simultaneously measure epidural and intrathecal drug concentrations. Resulting dialysate and plasma concentrations were used to calculate pharmacokinetic parameters for ropivacaine and bupivacaine. RESULTS: Co-administration of epinephrine decreased epidural clearance for ropivacaine [0.6 (sd 0.1) vs 0.4 (0.1) ml min(-1)] but not significantly for bupivacaine [1.2 (0.4) vs 0.8 (0.3) ml min(-1)]. The resultant increase in epidural area under the concentration-time curves (31% for ropivacaine and 52% for bupivacaine) was also observed in the intrathecal space (21% increase for ropivacaine and 37% for bupivacaine). There was no significant influence of epinephrine on ropivacaine plasma pharmacokinetics. Plasma Cmax for bupivacaine was decreased. CONCLUSIONS: These results show that epinephrine decreases the clearance and distribution processes involved in epidural disposition of ropivacaine and bupivacaine, leading to an increased uptake into the intrathecal space with an apparent more pronounced effect for bupivacaine.

The impact of age on bispectral index values and EEG bispectrum during anaesthesia with desflurane and halothane in children.

BACKGROUND: The 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. METHODS: ECG, 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. RESULTS: At 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. CONCLUSIONS: In 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.

Effect of remifentanil with and without atropine on heart rate variability and RR interval in children.

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 microg.kg(-1) atropine injection (AT + REMI) and the other ringer lactate solution (REMI). Three minutes later, a 1 microg.kg(-1) bolus of remifentanil was administered over 1 min, followed by a continual infusion at 0.25 microg.kg(-1).min(-1) for 10 min increased to 0.5 microg.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.

Impact of age on both BIS values and EEG bispectrum during anaesthesia with sevoflurane in children.

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.

Haemodynamic effects of remifentanil in children with and without intravenous atropine. An echocardiographic study.

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.

[Pediatric emergency department policy. Implementation and management of the resuscitation room]. / Recommandations concernant la mise en place, la gestion, l'utilisation et l'évaluation d'une salle d'accueil des urgences vitales pédiatriques.

The pediatric resuscitation room is the place where children suffering from vital distress are cared for in the emergency unit. Recommendations for its organization, functioning and evaluation have been ruled on by experts from six medical societies involved in these emergencies. They concern all the hospital's physicians, nurses and administrative directors.

Absolute bioavailability of midazolam after subcutaneous administration to healthy volunteers.

AIMS: Midazolam is given intravenously for induction of anaesthesia and conscious sedation and by subcutaneous infusion in patients in palliative care units. The objective of the present study was to determine the absolute bioavailability of subcutaneous midazolam and its pharmacokinetics in young, healthy, male volunteers. METHODS: Eighteen volunteers were given single doses of 0.1 mg kg-1 midazolam i.v. and s.c. after a wash-out period of 7-15 days in an open-label, randomized, cross-over study. Blood samples were collected up to 12 h post-infusion. Plasma concentrations of midazolam and of its two metabolites, 1'-OHM and 4-OHM, were assessed using an h.p.l.c.-MS method (LOQ 0.5 ng ml-1 for each analyte). Vital signs, cardiac parameters and oximetry were monitored. Local tolerance was determined and adverse events were also monitored. RESULTS: After s.c. infusion t(max) and C(max) were 0.51 +/- 0.18 h and 127.8 +/- 29.3 ng ml-1 (mean +/- s.d.), respectively. No statistically significant difference was detected in AUC(0, infinity ) after i.v. and s.c. administration. The mean (+/- s.d.) absolute bioavailability of subcutaneous midazolam was 0.96 (+/- 0.14) (CI 0.84, 1.03). Mean (+/- s.d.) t1/2 was similar after s.c. (3.2 (+/- 1.0) h) and i.v. infusion (2.9 (+/- 0.7) h), although a statistically significant difference was reached (P < 0.05). Mean CL and V of i.v. midazolam were 4.4 +/- 1.0 ml min-1 kg-1 and 1.1 +/- 0.2 l kg-1 (mean +/- s.d.), respectively. Plasma concentrations of 1'-OHM were higher than those of 4-OHM. Few mild and transient adverse events were noted and there were no clinically significant effects on EEG, blood pressure and laboratory parameters. CONCLUSIONS: This study has shown that subcutaneous midazolam has excellent bioavailability and that administration of midazolam by this route could be preferable when the intravenous route is inappropriate.

[Prevention of pain on injection with propofol in children: comparison of nitrous oxide with lidocaine]. / Prévention de la douleur à l'injection du propofol chez l'enfant: comparaison de l'inhalation de protoxyde d'azote à l'injection de lidocaïne.

INTRODUCTION: Injection pain caused by propofol is an important disadvantage, especially in children, incompletely reduced by adding lidocaine intravenously. Nitrous oxide's analgesic effects, well known, have never been evaluated on pain due to propofol. OBJECTIVE: To compare the effects of nitrous oxide with lidocaine on pain on injection caused by propofol in children. STUDY DESIGN: Double blind, randomised, prospective study. PATIENTS AND METHODS: 48 children aged more than 5 were randomly allocated to one of the 2 groups: N2O group, breathed 50% N2O + 50% O2 than received propofol only and Lido group breathed 100% O2 and received a mixture of propofol with lidocaine. The possible pain was scored during injection by a behavioural scale and once again in the recovery room by the child himself with a VAS. RESULTS: There was no significant difference in behavioural pain scores among the 2 groups; pain was assessed as being moderate or severe in 6/24 patients in N2O group and 10/24 in Lido group (behavioural scores > 1). Significantly more children in the N2O group had low VAS scores compared with the Lido group (no child/24 scored a VAS > 4 and 7/23 in the Lido group) demonstrating that N2O amnesic effects would omit the memory of pain caused by propofol. CONCLUSION: The use of nitrous oxide is an easy, cheap and efficient method to reduce the incidence of pain injection of propofol and his amnesic effects can provide real advantages in paediatric anaesthesia.

The effect of preoperative epidural morphine on postoperative analgesia in children.

IMPLICATIONS: We examined the effects of preoperative epidural morphine associated with general anesthesia on postoperative morphine requirements. Twenty-one children older than 6 yr scheduled for major surgery were randomly assigned to two groups, a control group and an epidural group that received a single epidural morphine injection.