The ASA Physical Status Classification: What Is the Evidence for Recommending Its Use in Veterinary Anesthesia?—A Systematic Review

Background: The effectiveness of the American Society of Anesthesiologists (ASA) Physical Status (PS) classification to identify the animals at a greater risk of anesthesia-related death and complications is controversial. In this systematic review, we aimed to analyze studies associating the ASA PS scores with the outcome of anesthesia and to verify whether there was any evidence for recommending the use of the ASA PS in veterinary patients.Methods: Research articles found through a systematic literature search were assessed for eligibility, and data were extracted and analyzed using random-effects analysis.Results: A total of 15 observational prospective and retrospective studies including 258,298 dogs, cats, rabbits, and pigs were included. The analysis found consistency between the studies showing that dogs, cats and rabbits with an ASA-PS ≥III had 3.26 times (95% CI = 3.04–3.49), 4.83 times (95% CI = 3.10–7.53), and 11.31 times (95% CI = 2.70–47.39), respectively, the risk of anesthesia-related death within 24 h (dogs) and 72 h (cats and rabbits) after anesthesia compared with those with an ASA PS <III. In addition, the analysis showed that dogs and cats with ASA PS ≥III had 2.34 times the risk of developing severe hypothermia during anesthesia (95% CI = 1.82–3.01).Conclusions: The simple and practical ASA PS was shown to be a valuable prognostic tool and can be recommended to identify an increased risk of anesthetic mortality until 24–72 h after anesthesia, and a greater risk of development severe intraoperative hypothermia

Paramètres influençant la structure et la fonction du globule rouge chez le cheval

The erythrocyte, as an oxygen carrier, is submitted to areas where oxidative stress is important. The maintenance of the structure and fluidity of its membrane is essential to its function. Indeed, oxygen must diffuse through the membrane and the deformability of the cell is essential to its progression through capillaries. The structure and, as a consequence, the fluidity of the membrane influence these properties. The red blood cell presents antioxydant capacities, but in some cases, free radical production is increased and exceeds antiradical defences leading to irreversible defects of the membrane, and, as a consequence, of its function. Horse erythrocyte seems to be more sensitive to oxidative stress than other species and resulting hemorheological changes could have tissular and organic consequences.Le globule rouge, de par sa fonction de transport de l’oxygène, est soumis à des milieux où le stress oxydant est important. Le maintien de la structure et de la dynamique de sa membrane est essentiel à la réalisation de sa fonction. En effet, l’oxygène doit pouvoir diffuser à travers la membrane et la cellule doit être capable de se déformer pour progresser dans les capillaires. La structure et, en conséquence, la fluidité de la membrane influencent ces propriétés. Le globule rouge présente des défenses antioxydantes importantes, mais dans certaines situations la production de radicaux libres est accrue et dépasse ces défenses aboutissant à des lésions irréversibles de la membrane cellulaire et donc de la fonction. L’érythrocyte équin semble plus sensible au stress oxydant que celui des autres espèces et les modifications hemorhéologiques qui en résultent peuvent avoir des conséquences au niveau tissulaire et organique.Peer reviewe

The effects of dietary N-3 and antioxidant supplementationon erythrocyte membrane fatty acid composition and fluidityin exercising horses

International audienceReasons for performing study: Fatty acid supplementation could modulate erythrocyte membrane fluidity in horses at rest and during exercise, but information is lacking on the effect of exercise. Objectives: To assess the effect of exercise with, and without, an oral antioxidant supplementation enriched with n-3 fatty acids on erythrocyte membrane fluidity (EMF) and fatty acid composition in eventing horses. Methods: Twelve healthy and regularly trained horses were divided randomly into 2 groups: group S received an oral antioxidant cocktail enriched in n-3 fatty acid (alphatocopherol, eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) whereas group P was placebo-treated. At the end of 4 weeks, all horses performed a standardised exercise test (ET) under field conditions. Venous blood was sampled before starting treatment (T0), immediately before (T1) as well as 15 mins (T2) and 24 h (T3) after ET. Spin labelled (16-DOXYL-stearic acid) red blood cell membranes were characterised using the relaxation correlation time (Tc in inverse proportion to EMF). Fatty acid composition (%) of the membrane was determined by gas-liquid chromatography. Results: Supplementation (group S) did not induce changes in EMF (T1 vs. T0) but significant changes in membrane composition were observed and there were increases in n-3 polyunsaturated fatty acid PUFA, n-3/n-6 ratio, and total n-3 fatty acids. Exercise (T2 vs. T1) induced a significant decrease of EMF in group P (Tc: +19%, P<0.05) and nonsignificant decrease in group S (Tc: +5%), whereas membrane fatty acid composition did not change in either group. During the recovery period (T3 vs. T2), EMF decreased significantly in group S (Tc: +29%, P<0.05) and nonsignificantly in group P (Tc: +18%) without any significant changes in fatty acid composition. Conclusion and potential relevance: An enriched oral antioxidant supplementation induced changes in membrane composition, which modulated the decrease in EMF induced by exercise. Long chain n-3 fatty acid supplementation might therefore be beneficial

Effects of oxygenation and exercise on equine erythrocyte membrane fluidity

L’intégrité de la structure et de la dynamique de la membrane plasmatique est essentielle à la fonction de la cellule. Cette intégrité peut être évaluée par la mesure de la fluidité membranaire globale, reflet de l’ensemble des mouvements des éléments membranaires au sein de la bicouche phospholipidique. Or l’intégrité de la membrane est menacée, entre autre, par les modifications de la structure lipidique résultant de lipoperoxidations. Ces peroxidations lipidiques résultent des attaques radicalaires par des espèces oxygénées activées (EOA) produites lors d’agression oxydante sur les acides gras membranaires.Nous posons l’hypothèse que les conditions d’oxygénations extrêmes, qui peuvent être rencontrées lors d’une anesthésie ou lors d’un stress oxydant induit par l’exercice chez le cheval, peuvent affecter la fluidité membranaire des érythrocytes et que ces variations peuvent être modulées par la modification de la structure membranaire du globule rouge par un supplément antioxydant oral adéquat. L’objectif de ce travail est donc d’évaluer les effets de différentes conditions d’oxygénation et d’oxydation in vitro (par contact avec différents mélanges gazeux), puis in vivo sous anesthésie générale (en faisant varier la fraction inspirée en oxygène) et à l’exercice, et enfin d’évaluer les effets d’une supplémentation enrichie en acides gras de type oméga-3 sur la fluidité membranaire du globule rouge. Les faibles pressions partielles en oxygène dans le sang artériel (PaO2), obtenues in vitro par contact du sang avec un gaz anoxique et in vivo sous anesthésie par inspiration d’air ambiant (500mmHg), ont induit un stress oxydant modéré qui n’a pas affecté la structure phospholipidique de la membrane malgré la peroxidation des acides gras de type oméga-6. La fluidité membranaire n’a pas été affectée par ces facteurs.In vivo, les pressions partielles élevées en oxygène observées dans le sang (>200mmHg) ont été insuffisantes pour induire des peroxidations significatives et des modifications de la fluidité membranaire. En revanche, les valeurs élevées de PaO2 ont augmenté la sensibilité du sang à l’hémolyse dans un premier temps, puis sa résistance 24 heures après un retour à la normoxie. Dans ces conditions aucun effet n’a été noté sur la viscosité du sang ni la perfusion musculaire.Par ailleurs, l’exercice intense semble diminuer la fluidité membranaire du globule rouge chez le cheval de sport. Cette diminution s’observe dès 15 minutes après l’arrêt de l’exercice et persiste 24 heures après. Il existe également des corrélations entre certains de ces marqueurs indirects et la fluidité membranaire. La supplémentation n’a pas eu d’effet significatif direct sur l’évolution de la fluidité membranaire observée au repos. Mais elle a pourtant influencé la structure de la membrane. En effet, la complémentation a induit une augmentation du pourcentage d’acides gras de type oméga-3 contenus dans la membrane érythrocytaire ainsi que du ratio oméga-3/oméga-6 pendant la période de repos. Cela résulte de l’incorporation sélective dans la membrane de l’acide eicosapentaénoïque (EPA) et de l’acide docosahéxaénoïque (DHA) apportés par voie orale. Mais aucune corrélation n’a été observée dans notre étude entre la composition en acides gras de la membrane et le marqueur de la fluidité membranaire. La supplémentation n’a pas eu d’effet significatif direct sur l’évolution de la fluidité membranaire observée à l’exercice, mais en a limité la diminution immédiate. Il résulte des études menées que : les conditions d’oxygénation les plus extrêmes qui peuvent être rencontrées en conditions atmosphériques ne semblent pas affecter la fluidité de la membrane. En revanche, un exercice intense, associé à une demande énergétique accrue, peut induire une diminution de la fluidité membranaire en corrélation avec les marqueurs du stress oxydant. Des modifications de la structure membranaire en acides gras polyinsaturés à longue chaîne de type oméga-3 n’affectent pas la fluidité membranaire mais modulent les effets du stress oxydant lors de l’exercice. La fluidité membranaire des érythrocytes pourrait être considérée comme un marqueur direct du stress oxydant dans certaines conditions. Mais ce marqueur semble moins sensible et global que d’autres marqueurs du stress cellulaire tels que le test d’hémolyse ou la mesure de la concentration plasmatique de peroxydes lipidiques spécifiques.The maintenance of plasmatic membrane integrity is mandatory for cell function. This integrity can be assessed by the measurement of global membrane fluidity which is proportional to the whole rotational and lateral diffusion rates of membrane components within the phospholipid bilayer. Membrane integrity could be threatened by changes in lipid structure as a result of lipid peroxidation by free radical species during oxidative stress. We hypothesize that extreme oxygenation status present during anesthesia or during exercise-induced oxidative stress in the horse can alter erythrocyte membrane fluidity (EMF), and that these changes in fluidity depend on variations in erythrocyte membrane structure under the action of an appropriate oral anti-oxidant supplementation.The aims of the study was:•to assess the effect(s) of various oxygenation and oxidative conditions firstly created in vitro (by contact between erythrocyte and different gaz mixtures), and secondly in vivo during general anesthesia (with varying inspired oxygen fractions) as well as during exercise.•To assess the effects of an omega-3 fatty acid-enriched supplementation on EMF.Low partial oxygen pressures, both obtained in vitro and in vivo under anesthesia (respectively 500 mm Hg) obtained in vitro induced a moderate oxidative stress which did not alter the phospholipidic structure of the membrane despite peroxidation of omega 6 fatty acids. Partial oxygen pressures obtained in vivo (>200 mm Hg) were unable to induce significant peroxidation and alteration in membrane fluidity. However, high PaO2 values initially increased sensitivity of blood to hemolysis, followed by a tendency towards resistance to hemolysis after 24hours.Intense exercise decreases EMF in the sports horse. This was observed as soon as 15 minutes after exercise and persisted during the recovery period 24 hours later. Correlations were found between oxidative stress indirect markers and membrane fluidity.Supplementation did not affect membrane fluidity but influenced membrane structure by increasing the pourcentage of omega-3 fatty acids and the omega3/omega6 ratio at rest. These changes resulted from selective incorporation into the membrane of orally provided EPA and DHA . However, we could not evidence a correlation between membrane composition and the marker of membrane fluidity (correlation-relaxation time Tc). During exercise, supplementation had no direct effect on variations of membrane fluidity but tapered its immediate decrease.In conclusion, our studies show that the most extreme conditions encountered under atmospheric conditions do not appear to affect EMF. However intense exercise combined with increased energetic requirements induces a decrease in EMF which correlates with variations in markers of oxidative stress. Modifications of membrane composition in long-chain omega-3 polyinsaturated fatty acids do not affect EMF but modulate oxidative stress during exercise. EMF could be a direct marker of oxidative stress under certain conditions but appears less sensitive and comprehensive than other markers of celllular stress such as the “hemolysis test” or the concentration in specific lipidic peroxidation products

Fatal tracheal collapse in a dog with brachycephalic syndrome during gastric endoscopic examination

International audienc

Sédation longue durée chez le cheval (évaluation de la qualité de la tranquilisation et du degré d'ataxie par perfusion de romifidine et de xylazine)

LYON1-BU Santé (693882101) / SudocTOULOUSE-EN Vétérinaire (315552301) / SudocSudocFranceF

Editorial: Anesthetic Risk and Complications in Veterinary Medicine

International audienceEditorial on the Research Topic Anesthetic Risk and Complications in Veterinary Medicine Veterinary practitioners have obligations to inform owners of the potential risks their animal might encounter during a surgery. A third of veterinarians believe that the majority of their clients are particularly concerned about their animal being anesthetized. The lack of a clear definition of anesthesia-related mortality and morbidity makes it difficult to specify the real anesthetic risk to the animals' owners. The timing a complication occurs, intra-or postoperatively, can also impose uncertainty in defining whether incidents are associated with the anesthetic procedure. Large veterinary multicenter studies defined anesthesia-related death as those occurring within 48 h (small animals) or 7 days (horses) of termination of the procedure, where anesthesia could not be excluded as being one of the contributory factors. Based on this definition, the authors identified an overall 0.17% anesthetic-related risk of death in dogs, 0.24% in cats, and 1.9% in horses. Such high rates compared with human patients warned clinicians and researchers on the need of improvements. Since then, several efforts have been made to increase the safety of animals undergoing anesthesia. This Research Topic was part of these efforts by creating an opportunity for the contribution of 35 researchers through 12 publications on the subject. They share, among others, the challenges found on the attempts to prevent the occurrence of deaths and complications. They also describe clinical complications and the successful management that was applied. Since 2002, when it was announced that horses have a high mortality rate associated with anesthesia, new equipment was developed to improve safety in this animal species. In 2008, Tafonius, the large animal anesthesia machine, was released with integrated monitoring and ventilator systems. The emerging technology allowed, among other features, to control the fresh gas flow into the breathing system either by a manually-or computer-driven flowmeter. The convenience of having a machine adjusting the flow of different gases to predetermined concentrations is an attractive feature and its accuracy was, therefore, tested by Raillard et al.. In this original article, the authors describe that the prediction of the isoflurane fraction course in the breathing system was challenging when using the computer-driven flowmeter. This was especially true at low inspired fractions of oxygen. The discrepancies between flows set on the controlled-driven flowmeter and actual lower delivered flows should be taken into consideration. Insufficient concentrations of inhalant anesthetics might lead to serious safety concerns, including both awaking of horses during anesthesia or unwarranted high concentrations of anesthetics that might result in cardiovascular and respiratory complications. An excessive delivery of inhalant anesthetics can significantly decrease the systemic vascular resistance and cause relative hypovolemia. This is of particular concern in equine patients since 20-50% of all anesthesia-related deaths in this animal species are associated with cardiovascular complications. The exact mechanisms are explained by Noel-Morgan and Muir who als

Etude d'alliages à mémoire de forme base Ru pour applications hautes températures

Les alliages base Ru allient effet mémoire de forme simple et températures de transformation martensitique élevées (entre 300C et 1100C). L objectif de cette thèse est d établir une base de connaissances sur le comportement haute température de ces alliages, afin de déterminer s ils peuvent être utilisés comme AMF haute température. La détermination des températures de transformations, qui présentent une faible hystérésis ainsi qu une grande stabilité au cyclage thermique, couplée à celle des structures cristallines a permis de réviser les diagrammes de phase des systèmes RuNb et RuTa et de classer les alliages en deux catégories. La première correspond aux alliages de structure tétragonale. Ils présentent une transformation martensitique de la phase cubique beta stable à haute température vers la martensite beta tétragonale qui donne lieu à l ambiante à une microstructure maclée selon les plans de type (101)t. Entrent dans la seconde catégorie les alliages de structure monoclinique. A la transformation précédente s ajoute au refroidissement une deuxième transformation de la phase beta vers la phase beta monoclinique qui fait intervenir des variants de translation. La quantification des déformations maximales récupérées associées à chacune des transformations et l observation in situ de la réorganisation des variants sous contrainte ont montré que l effet mémoire simple est essentiellement associé à la transformation beta/beta . L influence de l application d une contrainte sur la déformation associée à cette transformation a été étudiée lors de cycles thermomécaniques. Ceux-ci ont permis l obtention d un effet mémoire double à la transformation beta/beta .Shape memory alloys (SMAs) have the ability to perform both sensing and actuating functions. The operating temperatures of most SMAs depend on their martensitic transformation (MT) temperature. Ru-based alloys demonstrate both shape memory effect and high MT temperatures, which makes them a very promising option for high temperature SMAs. The determination of the crystallographic structures and the MT temperatures, which demonstrate both high stability and low hysteresis, enabled to clarify the literature phase diagram and to separate Ru-based alloys into two categories: Alloys undergoing a single MT which takes place on cooling from the cubic B2 beta-phase to a body centered tetragonal beta -phase. This MT gives rise to a highly twinned microstructure with a (101) compound twinning mode Alloys undergoing two displacive transformations on cooling as follows: beta beta beta . The second transformation gives rise to a monoclinic beta phase, which formation involves translation variants. The maximal shape recovery associated to each transformation was quantitatively studied and related to in situ TEM observations of the mechanisms involved during deformation. It was shown that the beta/beta MT is mainly responsible for the SME. Thermomechanical cycling was undertaken to perform the beta/beta MT under constant load and was able to induce two-way shape memory effect.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Détermination d'un rythme de perfusion de romifidine pour induire une sédation chez le cheval (effet de l'adminitration concomittante de butorphanol)

LYON1-BU Santé (693882101) / SudocTOULOUSE-EN Vétérinaire (315552301) / SudocSudocFranceF