Systematic gene deletion and functional characterization of histidine kinase phosphorelay receptors (HKRs) in the human pathogenic fungus Aspergillus fumigatus.

Histidine kinase receptors (HKRs) appear to be a common strategy for model and pathogenic fungi to sense and respond to environmental stresses. In the human pathogen Aspergillus fumigatus, which is responsible for invasive aspergillosis, 13 genes potentially encoding HKRs have been identified. Until now, only three HKRs have been functionally characterized. The aim of this study was to perform the systematic invalidation of A. fumigatus HKR genes and the careful phenotypic characterization of the relevant mutants. This study notably allowed to gain new important insights into the role of HKRs in physiology of A. fumigatus. Actually, we showed that (i) NikA/TcsC could be involved in the cell wall integrity pathway, (ii) Fhk6 and PhkA were involved in the regulation of the "fluffy" developmental program, (iii) PhkB could participate in the regulation of conidiation and (iv) PhkA was implied in the resistance of oxidative stresses.

Detailed product analysis during low- and intermediate-temperature oxidation of ethylcyclohexane.

An experimental study of the oxidation of ethylcyclohexane has been performed in a jet-stirred reactor with online gas chromatography, under quasi-atmospheric pressure (800 Torr), at temperatures ranging from 500 to 1100 K (low- and intermediate-temperature zone including the negative temperature coefficient area), at a residence time of 2 s, and for three equivalence ratios (0.25, 1, and 2). Ethylcyclohexane displays important low-temperature reactivity with a well-marked negative temperature coefficient behavior. In addition to 47 products with a mass lower than ethylcyclohexane which have been quantified, many species with a C(8)H(14)O formula (molecular weight of 126) were detected by GC-MS and 7 of them were quantified. These molecules are cyclic ethers, ketones, and aldehydes with the same carbon skeleton as the reactant. Experiments were also carried on under the same conditions for two other C(8) hydrocarbons, n-octane and 1-octene, showing that the reactivity of ethylcyclohexane is close to that of the alkene and lower than that of the alkane. Simulations using a detailed kinetic model of the literature allow a good prediction of the global reactivity and of the main hydrocarbon products for temperatures above 800 K. The main reaction channels leading to the observed reaction products at both low (below 800 K) and intermediate temperature (above 800 K) are discussed.

Noradrenaline use for septic shock in children: doses, routes of administration and complications.

AIM: To report our 10 year experience with noradrenaline use in children with septic shock focusing on doses, routes of administration and complications. METHODS: Retrospective single-centre review of children with septic shock who received noradrenaline between 2000 and 2010. RESULTS: We identified 144 children with septic shock treated with noradrenaline, in 22% as the first-line drug. The median volume resuscitation before vasoactive agent administration was 50 mL/kg interquartile range [IQR: 30-70]. Mean doses of noradrenaline ranged from 0.5 ± 0.4 µg/kg per min (starting dose) to 2.5 ± 2.2 µg/kg per min (maximum dose). Noradrenaline was administered via peripheral venous access or intra-osseous route in 19% of cases for a median duration of 3 h [IQR: 2-4] without any adverse effects. The use of noradrenaline increased over the study period. Mortality rate was 45% with a significant decrease over the study period. Adverse effects included arrhythmia in two children and hypertension in eight children. None of these arrhythmias required treatment and hypertension resolved with the noradrenaline dose reduction. CONCLUSION: Higher doses of noradrenaline than those suggested in the literature may be necessary to reverse hypotension and hypoperfusion. The use of noradrenaline through peripheral venous access or intra-osseous route was safe, without any adverse effects.

JTHERGAS: Thermodynamic Estimation from 2D Graphical Representations of Molecules.

JTHERGAS is a versatile calculator (implemented in JAVA) to estimate thermodynamic information from two dimensional graphical representations of molecules and radicals involving covalent bonds based on the Benson additivity method. The versatility of JTHERGAS stems from its inherent philosophy that all the fundamental data used in the calculation should be visible, to see exactly where the final values came from, and modifiable, to account for new data that can appear in the literature. The main use of this method is within automatic combustion mechanism generation systems where fast estimation of a large number and variety of chemical species is needed. The implementation strategy is based on meta-atom definitions and substructure analysis allowing a highly extensible database without modification of the core algorithms. Several interfaces for the database and the calculations are provided from terminal line commands, to graphical interfaces to web-services. The first order estimation of thermodynamics is based summing up the contributions of each heavy atom bonding description. Second order corrections due to steric hindrance and ring strain are made. Automatic estimate of contributions due to internal, external and optical symmetries are also made. The thermodynamical data for radicals is calculated by taking the difference due to the lost of a hydrogen radical taking into account changes in symmetry, spin, rotations, vibrations and steric hindrances. The software is public domain and is based on standard libraries such as CDK and CML.

Analysis of sequence and structural features that identify the B/C motif of U3 small nucleolar RNA as the recognition site for the Snu13p-Rrp9p protein pair.

The eukaryal Snu13p/15.5K protein binds K-turn motifs in U4 snRNA and snoRNAs. Two Snu13p/15.5K molecules bind the nucleolar U3 snoRNA required for the early steps of preribosomal processing. Binding of one molecule on the C'/D motif allows association of proteins Nop1p, Nop56p, and Nop58p, whereas binding of the second molecule on the B/C motif allows Rrp9p recruitment. To understand how the Snu13p-Rrp9p pair recognizes the B/C motif, we first improved the identification of RNA determinants required for Snu13p binding by experiments using the systematic evolution of ligands by exponential enrichment. This demonstrated the importance of a U.U pair stacked on the sheared pairs and revealed a direct link between Snu13p affinity and the stability of helices I and II. Sequence and structure requirements for efficient association of Rrp9p on the B/C motif were studied in yeast cells by expression of variant U3 snoRNAs and immunoselection assays. A G-C pair in stem II, a G residue at position 1 in the bulge, and a short stem I were found to be required. The data identify the in vivo function of most of the conserved residues of the U3 snoRNA B/C motif. They bring important information to understand how different K-turn motifs can recruit different sets of proteins after Snu13p association.

[Use of midazolam for refractory status epilepticus in children]. / Utilisation du midazolam dans l'état de mal épileptique réfractaire de l'enfant.

UNLABELLED: Morbidity and mortality are high in children with refractory status epilepticus (RSE). Here, we assess the efficacy of midazolam for RSE in children. METHODS: This was a retrospective analysis of 29 children admitted to the Lille University Hospital pediatric intensive care unit (PICU) for RSE between May 2006 and July 2008. The onset of the study corresponded with a new therapeutic protocol applied in the PICU for RSE where midazolam was proposed as the first-line treatment (bolus ten continuous infusion until control) to be replaced by thiopenthal in case of failure. RESULTS: We recorded 29 patients with RSE during the study period: 26 were treated with midazolam, including two where midazolam replaced thiopenthal because of hypotension. Midazolam successfully controlled RSE in 58% of patients. Mean delay to cessation of RSE was 48+/-65 minutes. Hypotension was observed in 8% of midazolam-treated patients and 71% of thiopenthal-treated patients. Overall mortality was 15% (4/26). Two deaths occurred long after the cessation of RSE. None of the deaths occurred in midazolam-treated patients. CONCLUSION: Midazolam is an efficient treatment for RSE in children. Morbidity and mortality appear to be lower with midazolam compared with other antiepileptic drugs used for the treatment of RSE.

Combustion of n-C3-C6 Linear Alcohols: An Experimental and Kinetic Modeling Study. Part I: Reaction Classes, Rate Rules, Model Lumping, and Validation.

This work (and the companion paper, Part II) presents new experimental data for the combustion of n-C3-C6 alcohols (n-propanol, n-butanol, n-pentanol, n-hexanol) and a lumped kinetic model to describe their pyrolysis and oxidation. The kinetic subsets for alcohol pyrolysis and oxidation from the CRECK kinetic model have been systematically updated to describe the pyrolysis and high- and low-temperature oxidation of this series of fuels. Using the reaction class approach, the reference kinetic parameters have been determined based on experimental, theoretical, and kinetic modeling studies previously reported in the literature, providing a consistent set of rate rules that allow easy extension and good predictive capability. The modeling approach is based on the assumption of an alkane-like and alcohol-specific moiety for the alcohol fuel molecules. A thorough review and discussion of the information available in the literature supports the selection of the kinetic parameters that are then applied to the n-C3-C6 alcohol series and extended for further proof to describe n-octanol oxidation. Because of space limitations, the large amount of information, and the comprehensive character of this study, the manuscript has been divided into two parts. Part I describes the kinetic model as well as the lumping techniques and provides a synoptic synthesis of its wide range validation made possible also by newly obtained experimental data. These include speciation measurements performed in a jet-stirred reactor (p = 107 kPa, T = 550-1100 K, φ = 0.5, 1.0, 2.0) for n-butanol, n-pentanol, and n-hexanol and ignition delay times of ethanol, n-propanol, n-butanol, n-pentanol/air mixtures measured in a rapid compression machine at φ = 1.0, p = 10 and 30 bar, and T = 704-935 K. These data are presented and discussed in detail in Part II, together with detailed comparisons with model predictions and a deep kinetic discussion. This work provides new experimental targets that are useful for kinetic model development and validation (Part II), as well as an extensively validated kinetic model (Part I), which also contains subsets of other reference components for real fuels, thus allowing the assessment of combustion properties of new sustainable fuels and fuel mixtures.

Combustion of n-C3-C6 Linear Alcohols: An Experimental and Kinetic Modeling Study. Part II: Speciation Measurements in a Jet-Stirred Reactor, Ignition Delay Time Measurements in a Rapid Compression Machine, Model Validation, and Kinetic Analysis.

This work presents new experimental data for n-C3-C6 alcohol, combustion (n-propanol, n-butanol, n-pentanol, n-hexanol). Speciation measurements have been carried out in a jet-stirred reactor (p = 107 kPa, T = 550-1100 K, φ = 0.5, 1.0, 2.0) for n-butanol, n-pentanol, and n-hexanol. Ignition delay times of ethanol, n-propanol, n-butanol, and n-pentanol/air mixtures were measured in a rapid compression machine at φ = 1.0, p = 10 and 30 bar, and T = 704-935 K. The kinetic subsets for alcohol pyrolysis and oxidation from the CRECK kinetic model have been systematically updated to describe the pyrolysis and high- and low-temperature oxidation of this series of fuels as described in Part I of this work (Pelucchi M.; Namysl S.; Ranzi E.Combustion of n-C3-C6 linear alcohol: an experimental and kinetic modeling study. Part I: reaction classes, rate rules, model lumping and validation. Submitted to Energy and Fuels, 2020). Part II describes in detail the facilities used for this systematic experimental investigation of n-C3-C6 alcohol combustion and presents a complete validation of the kinetic model by means of comparisons with the new data and measurements previously reported in the literature for both pyrolytic and oxidative conditions. Kinetic analyses such as rate of production and sensitivity analyses are used to highlight the governing reaction pathways and reasons for existing deviations, motivating possible further improvements in our chemistry mechanism.

Hyphal network whole field imaging allows for accurate estimation of anastomosis rates and branching dynamics of the filamentous fungus Podospora anserina.

The success of filamentous fungi in colonizing most natural environments can be largely attributed to their ability to form an expanding interconnected network, the mycelium, or thallus, constituted by a collection of hyphal apexes in motion producing hyphae and subject to branching and fusion. In this work, we characterize the hyphal network expansion and the structure of the fungus Podospora anserina under controlled culture conditions. To this end, temporal series of pictures of the network dynamics are produced, starting from germinating ascospores and ending when the network reaches a few centimeters width, with a typical image resolution of several micrometers. The completely automated image reconstruction steps allow an easy post-processing and a quantitative analysis of the dynamics. The main features of the evolution of the hyphal network, such as the total length L of the mycelium, the number of "nodes" (or crossing points) N and the number of apexes A, can then be precisely quantified. Beyond these main features, the determination of the distribution of the intra-thallus surfaces (Si) and the statistical analysis of some local measures of N, A and L give new insights on the dynamics of expanding fungal networks. Based on these results, we now aim at developing robust and versatile discrete/continuous mathematical models to further understand the key mechanisms driving the development of the fungus thallus.

[What become the decisions of limitation of treatments after discharge from the paediatric intensive care unit?]. / Que deviennent les décisions de limitation ou d'arrêt des traitements actifs à la sortie de réanimation pédiatrique ?

UNLABELLED: The fact that some children may survive despite a decision of limitation of treatments (DLT) is taken in Paediatric Intensive Care Unit (PICU) is a recent data. Although the French-speaking Group of Paediatric Intensive and Emergency Care (GFRUP) has published guidelines for limitation of treatments in PICU, outcome of these surviving children has not yet been studied. PURPOSES: To evaluate transmission of data concerning DLT in PICU toward teams in charge of children after the PICU stay and to evaluate perennility of these decisions. METHOD: Cohort study in children for whom DLT was discussed and who were discharged from PICU between 2002 and 2006. The study included an analysis of the medical files and discussions with the physicians in charge of children at the time of the study, including their responses to standardised scenarios concerning the outcome of their patients. RESULTS: Among the 96 children for whom DLT was discussed in PICU, 37 were discharged toward another unit. Only 1 discharge letter mentioned the DLT. At the time of the study, the Pediatric Overall Performance Category (POPC) score had increased in 16 children and was stable in 12. All the 6 children with a worsening POPC score died, without PICU readmission. The physicians in charge of children after the PICU stay did not remember any DLT. For 18 children (including 8 with previous DLT) PICU readmission would be proposed in case of life-threatening event. Their median POPC score at the time of study was lower than that of other children (3 versus 4; p=0.001). CONCLUSION: This study shows a lack of DLT data transmission, which is in contradiction with the GFRUP's guidelines. Correction of this lack is essential to improve cooperation between units in charge of these children.

[Interfaces for pediatric noninvasive ventilation (excluding neonate)]. / Interfaces pour la ventilation non invasive de l'enfant (à l'exclusion du nouveau-né).

The quality of noninvasive ventilation in pediatrics is interface-dependent. Several types of interfaces are currently available: nasal and oral masks, nasal pillows and helmets. Despite material improvements in material design, shape, size and components, interfaces are still not adapted for most children. The ideal interface must fit the child's characteristics and the disease requirements. For instance, a nasal canula is recommended for infants younger than 3 months of age. If necessary, nasal masks can be used as oronasal masks. Repeated and careful evaluations are indicated to ensure interface adequacy and to detect cutaneous injuries and facial deformities. Training is required for medical and paramedical personnel. Pediatrics studies, comparing interfaces, are needed to build evidence-based recommendations.

[Evaluation of the antibiotic prescription in a paediatric intensive care unit]. / Evaluation de la prescription antibiotique dans un service de réanimation pédiatrique.

UNLABELLED: The antibiotic prescription in intensive care units is frequent using often broad-spectrum antibiotics; its quality has never been evaluated in paediatric intensive care units. OBJECTIVES: To describe the modalities of antibiotic prescriptions in a paediatric intensive care unit and confront them to the literature guidelines and bacteriological data. METHODS: From January 1st to March 31st 2005, 52 consecutive prescriptions regarding 45 children, with a total of 47 hospitalisations were prospectively analysed. RESULTS: Confirmed diagnosis of bacterial infection was retained for 50 of the 52 patients: community acquired infection in 35 cases (70%) and a nosocomial infection in 15 cases. Ten children died during the antibiotic treatment (22%), with 5 deaths related to the infection (11%). Monotherapy represented 56% of the prescriptions of antibiotics. The initial antibiotic treatment was empirical in 42 of 52 cases (81%). The empirical prescriptions were documented afterward in 48% of cases. One or more microorganisms were isolated for 60% of the initial prescriptions. Misuses in antibiotic doses (in excess [10%] or by insufficiency [13%]), number of daily administration (4%), and way of administration and/or length of treatment were observed. Seventy-seven percent of the initial prescriptions seemed to be adapted to the identified or suspected bacteria, but only 63% adequate to recommendations. CONCLUSION: Almost 2/3rd of the antibiotic prescriptions were adequate to the recommendations. The implementation of standardized and specific protocols should contribute to improve the quality of these prescriptions.

[Non-invasive ventilation in infants with severe infection presumably due to respiratory syncytial virus: feasibility and failure criteria]. / Ventilation non invasive des nourrissons ayant une infection respiratoire sévère présumée à virus respiratoire syncitial: faisabilité et critères d'échec.

UNLABELLED: Beneficial effect of continuous positive airway pressure (CPAP) during non invasive ventilation (NIV) has been reported in infants with respiratory syncytial virus (RSV) infection, but no study has analyzed the predictors of its failure. OBJECTIVE: To evaluate the feasibility of NIV and to determine NIV failure criteria. POPULATION AND METHODS: All infants hospitalized in one PICU with presumed RSV infection between 2002 and 2006 were prospectively included. When respiratory support was needed, NIV was first started according to a pre-established protocol. RESULTS: One hundred and one infants, 43 females, 58 males, median age 49 days (range: 10-334), median weight 3.9 kg (range: 2,4-12) were included. RSV infection was confirmed in 84/101. Sixty-seven infants were transported by the paediatric medical transport system, 27 with NIV and 15 with invasive ventilation (IV). Fifteen infants were in IV at admission, 69 received NIV during their PICU stay (12 secondarily requiring IV) and 17 were never ventilated. A significant decrease in PCO2 with increase in pH was observed within 2 hours of NIV. Parameters associated with NIV failure were apneas, high values of admission PCO2 and H24 PRISM score. The 17 non-ventilated infants were older and had a lower severity score than those who were ventilated. CONCLUSION: In infants with RSV and needing respiratory support, NIV represented the sole method of respiratory support in 68% of cases. NIV failure criteria were apneas, high values of admission PCO2 and H24 PRISM score.

Structural rules and conformational compensations in the tRNA L-form.

The mitochondrial tRNAs (mtRNA) of five distinct, secondary structure types have been identified in the tRNA sequence compilation, and the three-dimensional modeling for representative sequences of these types has been carried out using a new criterion for the lengths of the helical domains and connector regions in a full-sized tRNA conformation. This criterion has been derived from the analysis of the known structures of cytosolic tRNAs and states that in the tRNA structure nucleotide 59 of the T-loop should stack onto Domain 1. To ensure this, Domain 1 must have 12 layers of stacked nucleotides, and in the case of a deletion of a base-pair in the T-stem, an additional 13th layer is required. Although a number of mitochondrial tRNAs harbored deficiencies in this criterion and, therefore, could not be modeled directly, this disability could be corrected and modeling accomplished by invoking structural compensations derived from one of two unusual aspects of these tRNAs. One class of these tRNAs contained an unpaired nucleotide in their anticodon stem, and their three-dimensional structure was successfully modeled when the unpaired nucleotide was intercalated into the helical domain of the stem. The second class contained more than the required number of nucleotides connecting the tRNA helical domains; the conformational flexibility of these nucleotides allowed them to take the place of the absent layers. The conformational compensation that we report rationalizes disparate features of these tRNAs and suggests that the stacking of nucleotide 59 on Domain 1 is an essential feature of the three-dimensional L-form of tRNA.

[Withholding or withdrawing life saving treatment in pediatric intensive care unit: GFRUP guidelines]. / Limitations et arrêts de traitements actifs en réanimation pédiatrique: recommandations du GFRUP.

Several recent French studies have revealed that 40% of death in pediatric intensive care units are associated with withdrawal or limitation of life saving treatments. Because such decisions are common, the Groupe francophone de réanimation et urgences pédiatriques (GFRUP) has decided to publish recommendations in order to help paediatricians dealing with those difficult issues and to improve their decisions. In a first part of the document the ethical principles that imply those guidelines are recalled, followed by definitions of the terms currently employed. The second part contains guidelines regarding decision making process, the way it is applied and organisation of relatives as well as paramedical and medical staff support when the death of a child occurs.

[Propranolol and lactatemia during hypovolemic shock: a case report]. / Propranolol et lactatémie durant un choc hypovolémique non septique : à propos d'une observation.

Lactate production results from anaerobic glycolysis. This pathway is recruited physiologically during intense and sustained muscular contractions. Hyperlactatemia may develop when tissue oxygenation is jeopardized such as in shock, its absence having been, however, sometimes reported in sepsis in which interactions between infectious agents and the organism's cells might blunt or disrupt hyperlactatemia development. During the course of acute rotavirus gastroenteritis, a 9-month-old girl developed severe dehydration (capillary-refill time, 5 s) leading to hypovolemic shock without signs of sepsis and with hypotension at 62/21 mmHg Surprisingly, the child failed to develop hyperlactatemia during shock. An etiologic search to understand why hyperlactatemia did not occur revealed that this patient had been receiving propranolol since the age of four months for the treatment of a Cyrano hemangioma. Via its inhibitory action on ß-adrenergic receptors, propranolol antagonizes the stimulation of glycolysis by catecholamines, which may be rationally proposed to have contributed to preventing hyperlactatemia during hypovolemic shock in this patient. Mechanisms by which propranolol can mediate this antihyperlactatemia action are further illustrated and discussed.

Modeling RNA-ligand interactions: the Rev-binding element RNA-aminoglycoside complex.

An approach to the modeling of ligand-RNA complexes has been developed by combining three-dimensional structure-activity relationship (3D-SAR) computations with a docking protocol. The ability of 3D-SAR to predict bound conformations of flexible ligands was first assessed by attempting to reconstruct the known, bound conformations of phenyloxazolines complexed with human rhinovirus 14 (HRV14) RNA. Subsequently, the same 3D-SAR analysis was applied to the identification of bound conformations of aminoglycosides which associate with the Rev-binding element (RBE) RNA. Bound conformations were identified by parsing ligand conformational data sets with pharmacophores determined by the 3D-SAR analysis. These "bioactive" structures were docked to the receptor RNA, and optimization of the complex was undertaken by extensive searching of ligand conformational space coupled with molecular dynamics computations. The similarity between the bound conformations of the ligand from the 3D-SAR analysis and those found in the docking protocol suggests that this methodology is valid for the prediction of bound ligand conformations and the modeling of the structure of the ligand-RNA complexes.

Protein C and S deficiency in severe infectious purpura of children: a collaborative study of 40 cases.

We studied, in 40 children (mean age: 52 months) with severe infectious purpura, the relationships between protein C (PC) and protein S (PS) levels, and shock, disseminated intravascular coagulation (DIC) and outcome. We determined, on admission, PC antigen (ELISA) and activity (chromogenic test), and total PS (ELISA). Results were expressed as % of normal adult values. Statistical analysis was performed with SAS. Thirty children were in shock, 20 had DIC. All children with DIC, and 10 without DIC were in shock. Of 20 children who were in shock and had DIC, 7 died and 3 had an amputation. PC antigen was significantly decreased in shock children (p less than 0.05), in children with DIC (p less than 0.0005), and in non-survivors (p less than 0.05). PC activity was significantly decreased in shock children (p less than 0.05), in children with DIC (p less than 0.0005), and in non-survivors (p less than 0.005). Total PS was not decreased in shock children, but was significantly decreased in children with DIC (p less than 0.005), and in non-survivors (p less than 0.005). We conclude that PC and PS levels were decreased in our children, and that PC levels were significantly decreased in the presence of shock, DIC, and fatal outcome. PC and antithrombin III (AT III) supplementation, should be evaluated in children with severe infectious purpura with shock and DIC.

Inhaled nitric oxide for a severe respiratory syncytial virus infection in an infant with bronchopulmonary dysplasia.

OBJECTIVE: To report the first case of ARDS in children treated with nitric oxide (NO) inhalation. METHODS: A 13-months infant presented with BPD and severe hypoxemia related to RSV infection and ARDS. Inhaled NO was delivered in the ventilatory circuit of a continuous flow ventilator (Babylog 8000, Dräger) in a concentration of 20-80 ppm for 7 days. NO and NO2 were continuously monitored (Polyton Draeger). Respiratory mechanics were evaluated by using the method of passive inflation by the ventilator. RESULTS: NO inhalation improved oxygenation (tcSaO2) and reduced respiratory system resistance without affecting arterial pressure. NO2 level remained below 5 ppm, and methaemoglobin level below 1%. The child survived without neurologic sequela. CONCLUSIONS: Two mechanisms to explain oxygenation improvement can be suggested: selective improvement in perfusion of ventilated regions and bronchodilation.

Reproducibility of the respiratory dead space measurements in mechanically ventilated children using the CO2SMO monitor.

OBJECTIVES: To assess the reproducibility of respiratory dead space measurements in ventilated children. DESIGN: Prospective study. SETTING: University pediatric intensive care unit. PATIENTS: Thirty-two mechanically ventilated children (0.13-15.4 years) who were clinically stable. METHODS: The single-breath CO(2) test (SBT-CO(2)) was recorded using the CO(2)SMO Plus from the mean of 30 ventilatory cycles during 1 h (at T0, T15, T30, T45, and T60). Airway dead space was determined automatically (Novametrix Medical Systems, USA), and manually by Bohr- Enghoff equations using data obtained by SBT-CO(2). At the end of the study period, arterial blood gas was sampled in order to calculate alveolar and physiologic dead space. Intrasubject reproducibility of measurements was evaluated by the intraclass correlation coefficient. Two-way analysis of variance was used to evaluate the relationships between time and measurements. The two methods for calculating airway dead space were compared by using two-tailed Student's t-test and Bland-Altman analysis. RESULTS: Airway dead space measurement had a good reproducibility during the 1-h period, whatever the method used (intraclass correlation coefficient: 0.84 to 0.87). No significant difference was observed with time. Airway dead space values from the SBT-CO(2) method were smaller than those from Bohr-Enghoff equations. Physiologic dead space values from the SBT-CO2 method were similar to those from Bohr-Enghoff equations. CONCLUSION: The measurement of airway dead space by the CO(2)SMO Plus was reproducible over a 1-h period in children requiring mechanical ventilation, provided ventilatory parameters were constant throughout the study. SBT-CO(2) analysis may provide a bedside non-invasive monitoring of volumetric capnography.