Effects of helium-oxygen on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in a porcine model of stable methacholine-induced bronchospasm

Objective: To explore the consequences of helium/oxygen (He/O2) inhalation on respiratory mechanics, gas exchange, and ventilation-perfusion (VA/Q) relationships in an animal model of severe induced bronchospasm during mechanical ventilation. Design: Prospective, interventional study. Setting: Experimental animal laboratory, university hospital. Interventions: Seven piglets were anesthetized, paralyzed, and mechanically ventilated, with all ventilator settings remaining constant throughout the protocol. Acute stable bronchospasm was obtained through continuous aerosolization of methacholine. Once steady-state was achieved, the animals successively breathed air/O2 and He/O2 (FIO2 0.3), or inversely, in random order. Measurements were taken at baseline, during bronchospasm, and after 30min of He/O2 inhalation. Results: Bronchospasm increased lung peak inspiratory pressure (49±6.9 vs 18±1cmH2O, P<0.001), lung resistance (22.7±1.5 vs 6.8±1.5cmH2O.l−1.s, P<0.001), dynamic elastance (76±11.2 vs 22.8±4.1cmH2O.l−1, P<0.001), and work of breathing (1.51±0.26 vs 0.47±0.08, P<0.001). Arterial pH decreased (7.47±0.06 vs 7.32±0.06, P<0.001), PaCO2 increased, and PaO2 decreased. Multiple inert gas elimination showed an absence of shunt, substantial increases in perfusion to low VA/Q regions, and dispersion of VA/Q distribution. He/O2 reduced lung resistance and work of breathing, and worsened hypercapnia and respiratory acidosis. Conclusions: In this model, while He/O2 improved respiratory mechanics and reduced work of breathing, hypercapnia and respiratory acidosis increased. Close attention should be paid to monitoring arterial blood gases when He/O2 is used in mechanically ventilated acute severe asthm

The NAOMI GAZL multispecies differential absorption lidar: realization and testing on the TADI gas leak simulation facility

International audienceWe report on a differential absorption lidar, designed for remote detection of CH 4 and CO 2 , based on a single-frequency 1.57-1.65 µm parametric oscillator/amplifier system. The lidar is tested on a controlled gas release facility

A Comprehensive Survey of Pelagic Megafauna: Their Distribution, Densities, and Taxonomic Richness in the Tropical Southwest Indian Ocean

The distribution and density of pelagic megafauna (marine mammals, seabirds, elasmobranches, and sea turtles) are important indicators of marine biodiversity, reflecting the condition of the underlying ecosystems. A dedicated aerial survey was conducted in the tropical Southwest Indian Ocean to map their distribution, the taxonomic diversity, and to estimate their densities to serve as a baseline for the area. This large survey across three ecological sub-regions revealed contrasting spatial distributions: maps of taxonomic richness of marine mammals and seabirds revealed different “hotspots” in the area. Densities were estimated for eight cetacean taxa with small and large Delphininae, or small Globicephalinae dominating, and for seven seabird taxa, with terns and noddies dominating. At the community level, the Southwest Indian Ocean megafauna was structured by the marine environment with strong differences between the Mozambique Channel and the Mascarene Islands, or between shelf and slope/oceanic habitats. Our results illustrate how multi-taxa aerial surveys are relevant and cost-effective monitoring tools for marine megafauna, allowing a community-wide approach

Estimation par géostatistique de la température moyenne de l'aquifère du Dogger (Bassin parisien) / Geostatistical estimation of the Middle Jurassic water level temperature

Zur Beschreibung des Temperaturfeldes wird eine geostatistische Methode benützt. Nach einer kurzen Beschreibung der theorestischen Grundlagen werden Temperaturefeldkarte des wasserführenden Dogger im Pariser Becken und eine Karte der Falscheinschätzungen der veränderlichen Grösse vorgelegt. Die Erkennung der fehlerhaften Abweichung unterstreicht die Vorteilhaftigheit dieser Methode.A geostatistical method is applied to define the temperature field's distribution. After a rapid theoretical presentation, the results are given as a map of temperature distribution for the Middle Jurassic water level (Paris basin) and a map of the kriging standard deviation. The estimated standard deviation is the most interesting part of the method.Les techniques de la géostatistique sont appliquées, en géothermie, à la modélisation du champ de température. Après un bref rappel de la méthode, les résultats obtenus sont présentés sous forme d'une carte d'estimation de la température moyenne de l'aquifère du Dogger (Bassin parisien) et d'une carte des erreurs sur l'estimation de la variable, en tout point. La connaissance de l'erreur possible sur la variable souligne l'intérêt de la méthode.Watremez Pierre, Gable Robert, Coleno Bernadette. Estimation par géostatistique de la température moyenne de l'aquifère du Dogger (Bassin parisien) / Geostatistical estimation of the Middle Jurassic water level temperature. In: Sciences Géologiques. Bulletin, tome 37, n°3, 1984. Informatique et modélisation en géologie et géochimie. pp. 213-219

A comparison of sevoflurane, target-controlled infusion propofol, and propofol/isoflurane anesthesia in patients undergoing carotid surgery: a quality of anesthesia and recovery profile.

In a prospective randomized study in patients undergoing carotid endarterectomy, we compared the hemodynamic effects, the quality of induction, and the quality of recovery from a hypnotic drug for the induction of anesthesia with sevoflurane, a target-controlled infusion (TCI) of propofol, or propofol 1.5 microg/kg followed by isoflurane. All patients were premedicated with midazolam and received sufentanil 0.4 microg/kg at induction. The induction of anesthesia was associated with a decrease in arterial blood pressure in all groups, but this was least pronounced in the Sevoflurane group. There were similar a number of episodes of hypotension, hypertension, and tachycardia among groups, but the incidence of bradycardia was less in the TCI group (P < 0.05) compared with the other groups. The duration of episodes of hypotension was shorter (P < 0.05) in the TCI Propofol group (1.9 +/- 2.3 min) compared with the Sevoflurane group (4.7 +/- 3.6 min). The duration of episodes of bradycardia was significantly lower (P < 0.05) in the TCI Propofol group (0.1 +/- 0.5 min) in comparison with the Propofol Bolus group (2.5 +/- 3.9 min). Similar doses of vasoactive drugs were used in all groups. The induction of anesthesia with sevoflurane was associated with inferior conditions for intubation in comparison with both Propofol groups, although the time to intubation was faster in the Sevoflurane group (P < 0.05). The recovery characteristics were similar in the three groups

End of the Century pCO(2) Levels Do Not Impact Calcification in Mediterranean Cold-Water Corals

International audienceOcean acidification caused by anthropogenic uptake of CO2 is perceived to be a major threat to calcifying organisms. Cold-water corals were thought to be strongly affected by a decrease in ocean pH due to their abundance in deep and cold waters which, in contrast to tropical coral reef waters, will soon become corrosive to calcium carbonate. Calcification rates of two Mediterranean cold-water coral species, Lophelia pertusa and Madrepora oculata, were measured under variable partial pressure of CO2 (pCO(2)) that ranged between 380 mu atm for present-day conditions and 930 matm for the end of the century. The present study addressed both short- and long-term responses by repeatedly determining calcification rates on the same specimens over a period of 9 months. Besides studying the direct, short-term response to elevated pCO(2) levels, the study aimed to elucidate the potential for acclimation of calcification of cold-water corals to ocean acidification. Net calcification of both species was unaffected by the levels of pCO(2) investigated and revealed no short-term shock and, therefore, no long-term acclimation in calcification to changes in the carbonate chemistry. There was an effect of time during repeated experiments with increasing net calcification rates for both species, however, as this pattern was found in all treatments, there is no indication that acclimation of calcification to ocean acidification occurred. The use of controls (initial and ambient net calcification rates) indicated that this increase was not caused by acclimation in calcification response to higher pCO(2). An extrapolation of these data suggests that calcification of these two cold-water corals will not be affected by the pCO(2) level projected at the end of the century