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.

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.

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.

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.

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.

Haematocrit and red blood cell transport in preterm infants: an observational study.

AIMS: To test whether cardiac output acts as a compensatory response to changes in haematocrit. METHODS: A cohort of 38 preterm infants (27-31 weeks' gestation) was studied with repeated Doppler measurements of left ventricular output during the 1st month of life. Red blood cell transport was calculated when the duct was closed. RESULTS: Multiple regression analysis showed that left ventricular output correlated negatively with haematocrit when the duct was closed (n = 84) and when it was open (n = 59). The influence of an increase of 10% in haematocrit absolute value on mean (SD) left ventricular output was estimated at -55 (11) ml/kg/min. Mean (SD) red blood cell transport was 132 (30) ml/kg/min with a mean (SD) intra-individual variability of 20% (8.8%). Red blood cell transport was increased more frequently by left ventricular output than by haematocrit. Haematocrit and left ventricular output but not red blood cell transport were dependent on postnatal age. CONCLUSION: These results suggest that in preterm infants cardiac output adaptation is effective in attenuating the effects of red blood cell mass variations on systemic oxygen carrying capacity.

[Influence of surfactants on hemodynamics during neonatal respiratory distress syndrome]. / Influence du surfactant sur l'hémodynamique du syndrome de détresse respiratoire néonatal.

The neonatal respiratory distress syndrome tends to delay the circulatory adaptation to extra-uterine life and leads to systematic hypotension. Haemodynamic changes following the instillation of surfactant are not stereotyped. They depend on the type of surfactant, the time of the instillation, the degree of prematurity, the severity of the respiratory disease and the mode of instillation. They are characterized by a transient haemodynamic instability with variable consequences on arterial pressure and systemic blood flow. The use of surfactant tends to decrease pulmonary arterial resistances and pulmonary arterial pressures but this effect is variable and is not obviously accompanied by long-term deleterious effect on the arterial duct. Haemodynamics and blood gases changes due to surfactant instillation have a variable effect on cerebral blood flow. The potential role of blood gas and haemodynamics changes on the occurrence of pulmonary haemorrhage or cerebral damage following instillation of surfactant remains poorly established but has to be taken into account.

[Analgesia controlled by the patient in pediatrics]. / L'analgésie contrôlée par le patient en pédiatrie.

The development of patient controlled analgesia (PCA) in children is the result of a search for an analgesia being both maximally efficient and secure, in the management of severe pain. The technique is based on self infusions of an analgesic, mainly morphine, by the child, through a special pump. The quality of the pump is essential in order to exclude any risk of overdosage. In order to prevent potential secondary effects and complications, a careful supervision is mandatory (clinical, by pulse oximetry, regular checking of pump parameters). PCA is applicable to children older than 5 years. The main indications are post-operative and oncological pains.

[Spontaneous colonic perforations revealing Ehlers-Danlos syndrome type IV]. / Perforations coliques spontanées révélatrices d'un syndrome d'Ehlers-Danlos de type IV.

BACKGROUND: The malignant form of Ehlers-Danlos syndrome type IV owes its bad reputation to a proneness to spontaneous rupture of bowel or large vessels, which may reveal the disease. CASE REPORT: A girl suffered acute rupture of the sigmoid at the age of 5 years and rupture of the left colon, twice, at the age of 11 and 13 years, respectively. These ruptures required colostomy and finally colectomy. A proneness to bruisability, history of dislocation of hips, hypermobile joints, ovarian cysts and some minor abnormalities of her face resembled that of the Ehlers-Danlos syndrome which was confirmed by optic and electronic microscopy of the skin biopsy. CONCLUSION: This is the youngest case of rupture of bowel reported in Ehlers-Danlos syndrome. Long-term prognosis is influenced by repetition of intestinal ruptures and occurrence of vascular complications.

[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.

[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.

[Syringomyelia discovered in the course of peridural anesthesia]. / Découverte d'une syringomyélie au décours d'une anesthésie péridurale.

Neurological symptoms after epidural anaesthesia suggest complications due to anaesthetic procedure. We report the case of a child who underwent perineal surgery in a gynaecological position under general and epidural anaesthesia, who experienced the day after surgery hypoesthesia of the whole left lower limb without any motor deficit. Magnetic resonance imaging excluded spinal compression, but revealed syringomyelic cavity extending from T9 to T11. Electromyogram evaluation was normal. Clinical signs completely vanished within 24 hours. This case emphasizes that the apparition of neurological signs after central nerve blocks is not only a complication of regional anaesthesia, but may reveal unknown neuropathy or result from surgical position or surgical procedure. Meticulous neurological examination, magnetic resonance imaging and electromyogram are immediately required.

[Comparative hemodynamic effects of sevoflurane and halothane at tele-expiratory concentration in intubation of infants]. / Effets hémodynamiques comparatifs du sévoflurane et de l'halothane à la concentration télé-expiratoire d'intubation chez le nourrisson.

OBJECTIVE: To compare the cardiovascular changes at the end-tidal concentrations of sevoflurane versus halothane required for tracheal intubation in infants (intubation MAC). STUDY DESIGN: Prospective randomized study. PATIENTS: Thirty-two infants, ASA physical status 1 or 2, scheduled for elective surgery, randomized to receive either halothane or sevoflurane for anaesthetic induction by inhalation. METHODS: Cardiovascular and echocardiographic data were recorded in both groups at baseline, and at the end-tidal concentrations needed for intubation. RESULTS: Intubation MAC was significantly less with sevoflurane than with halothane in infants. Sevoflurane did not change heart rate (HR) and cardiac index (CI) compared to values when awake. Sevoflurane significantly decreased blood pressure, systemic vascular resistance (SVR) and shortening fraction (SF). Myocardial contractility assessed by stress-velocity index (SVI) and stress-shortening index (SSI) decreased significantly at the intubation MAC, but did not fall into the abnormal range. Halothane caused a greater decrease in HR, SF, SSI, and CI than sevoflurane. CONCLUSIONS: Sevoflurane decreases cardiac output less than halothane in infants at the intubation MAC, due to a lower end-tidal concentration at intubation MAC and to less effects on haemodynamic variables.

[Sever acute pulmonary edema after peri-anesthetic laryngospasm in a newborn infant]. / Oedème pulmonaire aigu grave après laryngospasme peranesthésique chez un nouveau-né.

Severe acute pulmonary oedema following peranaesthetic laryngospasm in a newborn. The authors report a case of severe acute pulmonary oedema secondary to a laryngeal spasm in a 3-week-old neonate, immediately after induction of anaesthesia with halothane. After emergency tracheal intubation, the infant experienced a severe, life-threatening pulmonary oedema requiring prolonged intensive care. Such a secondary time course is unusual. Usually pulmonary oedema has a favourable outcome after oxygen administration and maintenance of positive expiration pressure, except in the neonate.

[Resuscitation in severe hepatic injuries]. / La réanimation des traumatismes hépatiques graves.

Hepatic injuries account for about 45% of all abdominal traumas and for 30 to 40% of penetrating abdominal injuries. In 60% of the cases, they are associated with other lesions, especially life-threatening head injuries. Abdominal ultrasonography, a short and safe procedure enabling guided puncture, has developed rapidly relegating to the second rank other diagnostic techniques such as peritoneal lavage and CT scan. First line treatment of severe trauma complicated by haemorragic shock combines fluid resuscitation, prevention of hypothermia and administration of broad spectrum antibiotics. Surgical care, relying mainly on perihepatic packing and vascular exclusion techniques must remain as conservative as possible. Once haemodynamics have been stabilized in patients who do not present any other abdominal lesion requiring laparotomy, the non-interventional attitude is often successful and bears lower morbidity.

[Pain conduction tracts. From physiology to practice]. / Les voies de la douleur de la physiologie à la pratique.

Some new theories concerning pain physiology have recently been suggested. Experimental facts show that despite its complexity, neuroplasticity is an established fact. The concept of preemptive analgesia is about to receive clinical applications. Nevertheless, the role of many opioid ligands which are involved in the pain physiology can explain the efficacy of some analgesia techniques. The authors review the physiological process of pain from its periphery to its centre and the ensuing practical applications. They point out the difficulty to apprehend peripheral analgesia, and the necessity of further researches concerning especially NMDA spinal receptors and other specific receptors.

[Septic thrombophlebitis of the lateral sinus: a rare but severe complication of mastoiditis in children]. / La thrombophlébite septique du sinus latéral: une complication rare mais redoutable de la mastoïdite chez l'enfant.

A case of lateral sinus thrombosis which occurred after mastoiditis in an 8 year old girl is reported. The elements of clinical diagnosis, the contribution of medical imaging and the medical and surgical management of this scarce but potentially severe affection are discussed.

[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.

[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.