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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Role of the α4ß2 nicotinic acetylcholine receptor in stroke recovery

Seto, Angela 27 June 2013 (has links)
Stroke is the leading cause of long-term disability in the developed world and can have devastating effects on the health and everyday functioning of individuals. In most cases stroke is ischemic and is caused by the obstruction of blood flow due to a clot in the brain blood vessels. This initiates a cascade of events that result in tissue death and loss of behavioural function associated with the damaged region. The peri-infarct cortex is a region surrounding the infarct core that survives the ischemic event and is most susceptible to pharmacological treatments and rehabilitation. α4ß2 nicotinic acetylcholine receptor (nAChR) signalling has been implicated as a mechanism that affects cell survival and cell death in the acute response after stroke. Nicotinic receptor signalling is also involved in modulating brain excitability, which can affect neural plasticity and restoration of cortical circuits and lead to recovery of lost function after stroke. In order to elucidate the role of α4ß2 nAChRs on acute and chronic recovery after stroke, we tested two hypotheses: (1) blocking α4ß2 nAChRs triggers acute neuroprotection and (2) α4ß2 nAChRs play a role in regulating plasticity and long-term functional recovery. In the first set of experiments a new model of targeted photothrombotic stroke was induced in a distal branch of the middle cerebral artery (MCA) in awake and anaesthetized mice. Mice treated with the α4ß2 nAChR antagonist dihydro-ß-erythroidine (DHßE) showed smaller lesion sizes relative to vehicle controls and this effect was greater in mice that were awake during stroke induction. To determine the mechanism of α4ß2 nAChRmediated neuroprotection, changes in collateral flow were measured using Evans bluestained surface angiograms and laser Doppler flowmetry. Contrary to what was expected, DHßE did not appear to induce neuroprotection by altering collateral flow. In the second set of experiments, we first used confocal imaging to quantify and characterize the expression of α4ß2 nAChRs after stroke. Next, mice were induced with a targeted photothrombotic stroke in the forelimb somatosensory cortex. Mice were then chronically treated with DHßE to determine if α4ß2 nAChR antagonism could improve recovery of function. Behavioural tests showed that blocking α4ß2 nAChRs chronically had no effect on forelimb function after stroke. Voltage-sensitive dye imaging was used to measure forelimb-evoked responses in the somatosensory cortex and revealed no differences in cortical responsiveness between treated and non-treated groups. Altogether, these results show that changes in α4ß2 nAChR signalling that occur after stroke mediate ischemic cell death but do not have an effect on long-term recovery and plasticity. Moreover, they present a novel pathway for investigating stroke pathophysiology and the development of acute neuroprotective treatments. / Graduate / 0317 / aseto@uvic.ca
52

Pinçamento digital e estímulo elétrico na determinação da Concentração Anestésica Mínima (CAM) de isofluorano em galinhas prétratadas ou não com meloxicam / Toe pinch and electrical stimulation in determining the Minimum Anesthetic Concentration (MAC) of isoflurane in chickens pre-treated or not with meloxicam

Costa, átila 19 November 2009 (has links)
Made available in DSpace on 2016-12-08T16:24:07Z (GMT). No. of bitstreams: 1 PGCA09MA051.pdf: 896959 bytes, checksum: fead018a3cd8ddb84de936e3f798d903 (MD5) Previous issue date: 2009-11-19 / The toe pinch has been the nociceptive stimuli in determining the minimum anesthetic concentration (MAC) in birds. In mammals electrical simulation has been used with high accuracy and repeatability. The non steroid anti-inflammatory meloxicam, has been used safely in birds, but its efficacy and safety during anesthesia, is still unknown. Thirty chickens (Gallus gallus) healthy, same batch, age 30 to 45 weeks, and weight of 1.733 ± 266kg, were randomly allocated into five groups, respecting an interval of at least 10 days in birds reused. In the first part, were assessed two types of nociceptive stimulation for CAM determination, the toe pinch (P), and two forms of electrical stimulation (30mA; 50Hz); aluminium plates on the foot (E1), and hypodermic needles in the leg (E2). In the second part, we evaluated the CAM birds pre-treated with meloxicam (0.5 mg / kg, IM, 15 min. before induction), using the toe pinch (MP) and electrical stimulation with needles (ME), both about 60 minutes after meloxicam. After 15 minutes for equilibration the anestetic concentration, arterial blood gases, and cardiorespiratory parameters were obtained before and after the nociceptive stimuli. The CAM determination was through the upand- down method. Was considered significant when p < 0,05. The MAC of isoflurane in group P was 1.11 ± 0.08% in E1 0.92 ± 0.21%, and E2 1.47 ± 0.10%. In the groups pre-treated with meloxicam, MP was 0.75 ± 0.08%, 32% less than P (p <0.001), and ME was 1.27 ± 0.02%, 14% to E2 (p <0.001). The stimulus in E2 was the most intense (supramaximal) and validated in the determination of MAC in birds. The toe pinch, although not supramaximal, obtained an similar precision to E2, when not pretreated. The stimulus in E1 was considered invalid. Chickens when pre-treated with meloxicam had lower values of CAM / O pinçamento de dedo tem sido o estimulo nociceptivo na determinação da concentração anestésica mínima (CAM) em aves. Em mamíferos o estímulo elétrico tem sido utilizado, buscando maior acurácia e repetibilidade. O anti-inflamatório não esteroidal meloxicam, tem sido utilizado com segurança em aves, porém sua eficácia e segurança durante anestesia inalatória, ainda é desconhecida. Trinta galinhas (Gallus gallus) saudáveis, de mesmo lote, idade de 30 a 45 semanas, e peso de 1,733 ± 266kg, foram alocadas aleatoriamente em cinco grupos, sempre respeitando um intervalo de no mínimo 10 dias nas aves reutilizadas. Na primeira parte, foram avaliadas duas modalidades de estimulação nociceptiva para determinação de CAM; o pinçamento de dedo (P), e duas formas de estímulo elétrico (30mA;50Hz), placas de alumínio na pata (E1), e agulhas hipodérmicas na coxa (E2). Na segunda parte, foi avaliada a CAM de aves pré-tratadas com meloxicam (0,5 mg/kg;IM;15 min. antes indução), utilizando o pinçamento de dedo (MP), e estímulo elétrico com agulhas (ME), ambos aproximadamente 60 minutos após meloxicam. Após 15 minutos para equilíbrio da concentração anestésica, parâmetros cardiorrespiratórios e hemogasométricos foram obtidos antes, e depois do estimulo nociceptivo. A determinação da CAM foi através do método up-and-down. Foi considerado significativo quando p<0,05. A CAM do isofluorano no grupo P foi 1,11 ± 0,08%, no E1 0,92 ± 0,21%, e no E2 1,47 ± 0,10%. Nos grupos pré-tratados com meloxicam, MP foi 0,75 ± 0,08%, 32% menor que P (p<0,001), e ME foi 1,27 ± 0,02%, 14% que E2 (p<0,001). O estimulo no E2 foi o mais intenso (supramáximo), sendo validado na determinação de CAM em aves. O pinçamento de dedo, apesar de não ser supramáximo, obteve uma precisão semelhante a E2, quando não pré-tratados. O estímulo em E1 foi considerado inválido. Galinhas quando pré-tratadas com meloxicam apresentam menores valores de CAM
53

Administração intravenosa de emulsão lipídica de isofluorano em cães /

Almeida, Ricardo Miyasaka de. January 2008 (has links)
Orientador: Carlos Augusto Araujo Valadão / Banca: Newton Nunes / Banca: Paulo Sérgio Patto dos Santos / Banca: Aury Nunes de Moraes / Banca: Nilson Oleskovicz / Resumo: A administração intravenosa de anestésicos voláteis halogenados pode ser considerada uma alternativa à aplicação pela via inalatória, e neste contexto, as formulações emulsificadas têm mostrado segurança, eficiência e bons planos anestésicos. Neste estudo, objetivou-se comparar os efeitos hemodinâmicos e respiratórios das administrações intravenosa e inalatória de isofluorano em cães, após a determinação da taxa de infusão intravenosa de 6,99 mL/kg/h deste halogenado em emulsão lipídica. Para tanto, foram utilizados oito cães, os quais formaram três grupos distintos: grupo IV - anestesia intravenosa por infusão de emulsão lipídica com isofluorano; grupo E - anestesia inalatória com isofluorano, associada à infusão intravenosa de emulsão lipídica sem o halogenado; e grupo IN - anestesia inalatória com isofluorano, associada à infusão intravenosa de solução de NaCl 0,9%. Foram evidenciadas diminuições da contratilidade cardíaca, índice cardíaco e pressão arterial sistêmica a partir de 10 e 40 minutos de anestesia, respectivamente, nos grupos IV e E. A hipotensão no grupo IV resultou em acidose metabólica, porém, hipoxemia não foi observada. O grupo IN apresentou manutenção do índice cardíaco, apesar de reduções do índice de resistência vascular sistêmica e pressão arterial. A taxa de infusão intravenosa determinada foi efetiva na manutenção de plano de anestesia cirúrgica em cães. As infusões intravenosas de isofluorano e emulsão lipídica causaram depressão cardíaca e hipotensão. Em relação à função respiratória, nenhum dos grupos mostrou efeitos deletérios. / Abstract: The intravenous administration of halogenated anesthetics can be considered an alternative to the application by the inhalation route, moreover, emulsified formulations have been showing safety, efficiency and appropriated anesthetic depth. The aim of this study was to compare the effects of isoflurane anesthesia by intravenous or inhalational route on hemodynamic and respiratory variables, after the determination of the intravenous infusion rate of 6.99 mL/kg/h of this anesthetic in lipid emulsion, in dogs. Therefore, eight dogs were distributed in three different protocols: IV group - intravenous anesthesia with emulsified isoflurane; E group - inhalational anesthesia with isoflurane associated to intravenous infusion of lipid emulsion; and IN group - inhalational anesthesia with isoflurane associated to intravenous infusion of 0.9% NaCl solution. The results regarding IV and EM groups revealed decreases of heart contractility, cardiac index and systemic blood pressure starting from 10 and 40 minutes of anesthesia, respectively. The hypotension in the IV group resulted in metabolic acidosis, however, hypoxemia was not observed. The IN group demonstrated maintenance of cardiac index, despite of reduction of the blood pressure and systemic vascular resistance index. The intravenous infusion rate determined was effective in the maintenance of an anesthetic depth of general anesthesia in dogs. The intravenous infusions of isoflurane and lipid emulsion caused cardiac depression and hypotension. In relation to respiratory function, the inhalational route and the intravenous infusions of isoflurane and lipid emulsion did not result in harmful effects. / Doutor
54

Efeito da eletroacupuntura em gatas (felis catus domesticus) anestesiadas por isofluorano e submetidas à ovariosalpingohisterectomia / Effect of electroacupunture on female cats (felis catus domesticus) anesthetized with isoflurane and submitted to ovariosalpingohysterectomy

Melo, Mariana da Silva 03 August 2005 (has links)
Acupuncture is a way of treating and causing analgesia by inserting needles into the skin at certain points. Among those methods to stimulate such points, electroacupuncture (EA) distinguishes itself because it causes preemptive analgesia with cardiorespiratory stability and reduces anesthetic dosage. In this regard, the goal of this work was to evaluate anesthetic consumption and cardiorespiratory parameters in 20 female cats pretreated with acepromazine, anesthetized with isoflurane, stimulated in the pre- and transoperative periods with EA, and submitted to elective ovariosalpingohysterectomy. The cats were gathered into two groups: G1 (control) and G2 (electroacupuncture). Once reached the steadystate level, needles were inserted at false points along the G1 cats body, with the electrostimulation device being kept off. Regarding the G2 cats, needles were bilaterally inserted at the points Zusanli (ST36) and Yanglingquan (GB34), with electroacupuncture being performed at frequencies of 2 and 100 Hz, in square wave, with alternating current, and intensity ranging from 2 to 3 mA; it begun 30 minutes prior to the surgery and lasted till the end of the latter. In this double-blind study, variables studied were isoflurane consumption, body temperature, respiratory and heart rate, oxyhemoglobin saturation, and mean arterial pressure. Comparatively with the control group, electroacupuncture increased oxyhemoglobin saturation (p<0,05) and reduced mean arterial pressure (p<0,05). There was no relevant difference between G1 and G2 concerning the other variables. / A acupuntura consiste na inserção de agulhas em pontos específicos do corpo com finalidade terapêutica e analgésica. Dentre os métodos para estimulá-los, a eletroacupuntura (EA) destaca-se por promover analgesia com estabilidade cardiorrespiratória, além de reduzir doses de anestésicos. Nesse sentido, objetivou-se com este experimento avaliar o consumo de anestésico e parâmetros cardiorrespiratórios em 20 gatas pré-tratadas com acepromazina, anestesiadas por isofluorano, estimuladas no pré- e transoperatório com EA e submetidas à ovariosalpingohisterectomia eletiva. Os animais foram separados em dois grupos de igual número: G1 (controle) e G2 (eletroacupuntura). Uma vez adquirido o plano anestésico, nas gatas do G1 foram introduzidas agulhas em pontos falsos e o aparelho de eletroestimulação permaneceu desligado; nas do G2, foram introduzidas bilateralmente nos pontos Zusanli (E36) e Yanglingquan (VB34), e a EA foi realizada com freqüências de 2 e 100 Hz, em onda quadrada, com corrente alternada e intensidade variando de 2 a 3 mA iniciando 30 minutos antes de a cirurgia começar e finalizando ao término desta. O estudo foi cego, e como variáveis estudaram-se: consumo de isofluorano, temperatura corpórea, freqüências respiratória e cardíaca, saturação de oxi-hemoglobina e pressão arterial média. Comparativamente ao grupo controle, a EA aumentou a saturação de oxihemoglobina (p<0,05) e reduziu a pressão arterial média (p<0,05); as demais variáveis não diferiram significativamente entre os grupos. / Mestre em Ciências Veterinárias
55

Determinação da variação da pressão de pulso em equinos anestesiados com isofluorano e mecanicamente ventilados submetidos à reposição volêmica / Pulse pressure variation in mechanical ventilated isoflurane anesthetized horses submitted to fluid challenge

Eutálio Luiz Mariani Pimenta 21 March 2016 (has links)
Objetivo: Determinar a relação entre a &#916;PP e a responsividade à expansão volêmica em equinos anestesiados com isoflurano e mecanicamente ventilados. Método: Em estudo prospectivo, oito cavalos Árabes saudáveis (366,5 &#177; 22,7kg) foram anestesiados. Todos os animais foram aleatoriamente alocados em dois grupos: (I) restrição hídrica de 14h; (II) restrição hídrica de 14h mais pneumoperitôneo de 12mmHg. Anestesia foi induzida com detomidina, diazepam e cetamina e mantida com isoflurano a 1,6% (I) e 1,3 % (II) em todos os animais mecanicamente ventilados (VTexp 14mL/kg) e posicionados em decúbito dorsal. I - Após 30 minutos da indução anestésica foi coletado os parâmetros basais (TBasal) e os animais submetidos a desafio volêmico (DV) com Ringer com Lactato de sódio (15 mL/kg, 15 min) (T1). Animais responsivos (DC > 15%) receberam até dois DV adicionais (T2 e T3, respectivamente). Caso considerado não responsivo, foi administrada dobutamina titulada para PAM 65-75 mmHg por 15 minutos (T4) e após foi realizado novo DV (T5). II Ídem acima, porém após TBasal foi instituído pneumoperitônio (12mmHg) por 15 minutos (PNP) e os desafios realizados com pneumoperitônio. Após (T5), foi descontinuada a hiperdistenção abdominal e coletado os valores (T6). Resultados: FaseI: Não houve aumento significativo no IC em T1 e T4. Porém, houve aumento de 16,5% após novo DV (T5). Não houve aumento significativo na PAM em T1. Porém houve aumento em T4, sem aumento adicional após novo DV (T5). Os valores de &#916;PP e &#916;PS reduziram em T4, T5 e em T1, T4 e T5, respectivamente, em relação ao valor basal. Porém não houve diferença estatística quando comparados animais responsivos dos não responsivos. Houve aumento de 293% da PVC em T1, mantendo se acima do valor basal por todos os demais momentos. A AUC obtida através da curva ROC foi de 0,83, 0,83 e 0,40 para &#916;PP, PAM e PVC, respectivamente para T1 e T2; e 0,55, 0,69 e 0,65 incluíndo T5. FaseII: Não houve alteração significativa no IC e &#916;PP em todos os tempos observados. Houve aumento significativo na PAM em relação a Tbasal após DV sob pneumoperitônio (T1). Aumento adicional foi observado após novo desafio volêmico (T5). Os valores de PS reduziram somente após descontinuado pneumoperitônio (T6). Porém não houve diferença estatística quando comparados animais responsivos dos não responsivos. Houve aumento de 363% da PVC após pneumoperitônio (PNP), com aumento adicional de 189% após DV em T1, mantendo se acima do valor basal por todos os demais momentos. Novo aumento foi observado em T5, retornando para valores similares a PNP em T6. A AUC obtida através da curva ROC foi de 0,64, 0,50 e 0,29 para &#916;PP, PAM e PVC, respectivamente para T1 e T2; e 0,71, 0,64 e 0,61 incluíndo T5. Conclusão: Utilizando a metodologia empregada, o &#916;PP não mostrou ser índice preditivo de responsividade volêmica em equinos anestesiados com isoflurano e mecanicamente ventilados, ocorrendo piora quando empregado pneumoperitônio de 12 mmHg. O emprego da dobutamina também reduziu a sensibilidade/especificidade deste índice. Portanto, acredita-se que o uso desta ferramenta seja limitado na espécie equina / Objective: To determine the relationship between &#916;PP and fluid responsiveness in mechanically ventilated isoflurane anesthetizes horses. Method: In a prospective study, 8 adult healthy Arabian horses (366.5 &#177; 22.7kg) were anesthetized. All animals were randomly submitted in two groups: (I) 14h of water restriction; (II) 14 h of water restriction associated with 12mmHg of pneumoperitoneum. Anesthesia was induced with detomidine, diazepam and ketamine and maintained with 1.6% (I) or 1.3% (II) end-tidal concentration of isoflurane and all animals were placed dorsal recubency and mechanically ventilated (VTexp 14mL / kg). I - Baseline parameters was collected (TBasal) after 30 minutes of anesthetic induction and animals subjected to blood fluid challenge (VE) with lactate Ringer solution (15 mL / kg, 15 min) (T1). Responsive animals (DC> 15%) received up to two additional VE (T2 and T3, respectively). Dobutamine was given titrated to achieve PAM 65-75 mmHg for 15 minutes (T4) if animals were considered unresponsive. After was submitted to a new VE (T5). II - As described above, with difference after TBasal was established pneumoperitoneum (12 mmHg) for 15 minutes (PNP) and the challenges were realized in animals with pneumoperitoneum. After (T5) abdominal distension was discontinued and collected all values (T6). Results: Phase I: There was no significant increase in CI at T1 and T4. However an increase of 16.5% after new VE (T5). There was no significant increase in MAP at T1. But there was an increase at T4 with no further increase after new VE (T5). &#916;PP and &#916;PS values decreased compared to TBasal at T4, T5 and T1, T4 and T5, respectively. But there was no statistical difference when compared responsive with unresponsive animals. There was an 293% increase of PVC at T1, keeping above the baseline for all other times. The AUC obtained from ROC curve was 0.83, 0.83 and 0.40 for &#916;PP, PVC and CVP respectively for T1 and T2; and 0.55, 0.69 and 0.65 including T5. Phase II: No significant change in CI and &#916;PP in all observed times. Significant increase in MAP compared with Tbasal after DV under pneumoperitoneum (T1) was observed. With additional increase after new VE (T5). &#916;PS values reduced only after discontinued pneumoperitoneum (T6). However there was no statistical difference when compared responsive with unresponsive animals. There was an 363% increase of PVC after pneumoperitoneum (PNP), with an additional increase of 189% after DV at T1, keeping above the baseline for all other times. Further increase was observed in T5, returning to values similar to PNP at T6. The AUC obtained from the ROC curve was 0.64, 0.50 and 0.29 for &#916;PP, PVC and &#916;PS respectively for T1 and T2; and 0.71, 0.64 and 0.61 including T5. Conclusion: With the methodology employed, the PP not shown to be a predictor of responsiveness volume in horses anesthetized with isoflurane and mechanically ventilated, occurring worsening when used pneumoperitoneum 12 mmHg. The use of dobutamine also reduced the sensitivity / specificity of this index. Therefore the use of this this tool appears limited in horses
56

Therapeutic approaches for two distinct CNS pathologies

Stumpf, Sina Kristin 25 June 2018 (has links)
No description available.
57

L'utilisation de l'halothane et de l'isoflurane en neurophysiologie visuelle chez le chat

Villeneuve, Martin 07 1900 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal. / L'halothane est à l'heure actuelle, l'anesthésiant volatile le plus répandu en recherche animale. Comme plusieurs autres agents, il produit d'importantes altérations aux organes de l'animal, tout spécialement au cerveau. L'utilisation d'un agent plus récent, l'isoflurane, procure certains avantages comparativement à l'halothane. Par contre, personne n'est dans une bonne position pour recommander l'utilisation de l'isoflurane en électrophysiologie, car ses effets sur les fonctions cérébrales sont peu connus. En sachant que les deux agents agissent de façon différente sur l'activité globale du cerveau (EEG, PEY), il est probable qu'ils agissent également de façon différente sur l'activité unitaire des neurones. Il est fondamental de résoudre cette incertitude lorsqu'on considère qu'un bon nombre d'études explorent les fonctions de régions du cerveau en se basant sur les propriétés des cellules constituant ces régions. L'objectif de cette étude est de déterminer, entre l'halothane et l'isoflurane, l'anesthésique de choix pour l'étude des propriétés des champs récepteurs des cellules du cortex visuel primaire du chat. La distinction principale entre les deux agents anesthésiques testés est que, à des multiples de CAM équivalents, l'isoflurane réduit davantage l'amplitude des réponses visuelles optimales. Compte tenu de son effet dépresseur, l'isoflurane ne serait pas l'agent anesthésique à recommander pour les études électrophysiologiques en vision et possiblement aussi pour tous les autres systèmes sensoriels. / Halothane is presently the most widely used volatile anesthetic in animal research. As many anesthetics, it produces several alterations on organs, especially on the brain. Recently, another volatile anesthetic, isoflurane, emerged in neuroscience laboratories. Despite the fact that isoflurane appears to be a better anesthetic than halothane for animal brain research, no one is in a firm position to recommend it in electrophysiology research because its effect on specific brain functions are relatively unknown. Given that both anesthetics yield different action on gross brain activity (EEG, VEP), it is likely that they may also differentially affect single neuron activity. This is fundamental when considering that many studies investigate the function of brain areas on the basis of response properties of their comprising neurons. The main goal of this study is to determine the best anesthetic between halothane and isoflurane to study receptive field properties of neurons in the cat' s primary visual cortex. Results indicate that various cell response parameters differ under halothane compare to isoflurane anesthesia. The main diff erence between the two anesthetics tested is the greater depression of the cell optimal visual response amplitude induced by isoflurane anesthesia at equipotent concentration. Due to is depressive effects isoflurane may not be the ideal anesthetic for electrophysiological studies in vision has well has other sensory systems.
58

Comparison of Small Volume Bolus Administration of Hypertonic Saline, Colloid, and Hypertonic Saline-Colloid Combination in Dogs with Isoflurane-Induced Hypotension

Gerken, Katherine 04 September 2018 (has links)
No description available.
59

Estudio comparativo de la velocidad y calidad de inducción y recuperación anestésica con isofluorano y sevofluorano en gatos premedicados

Escobar Gil de Montes, María Teresa 11 March 2011 (has links)
Se compararon dos experiencias de inducción anestésica en seis gatos premedicados con acepromacina y buprenorfina: cámara (exp. 1) o mascarilla (exp. 2). En cada experiencia se empleó isofluorano o sevofluorano vehiculados en oxígeno o en una mezcla de oxígeno y óxido nitroso según grupo. Se valoró la calidad de forma subjetiva y la velocidad de inducción en base a distintos tiempos medidos durante esta fase. Tras un mantenimiento de treinta minutos en el que se registraron distintos parámetros cardiorrespiratorios y la temperatura corporal, se evaluó la calidad y velocidad de recuperación anestésica. No se observaron diferencias en cuanto a los tiempos o calidad de inducción o recuperación anestésica entre isofluorano o sevofluorano con o sin óxido nitroso. Los parámetros cardiorrespiratorios durante el mantenimiento fueron similares entre grupos. En conclusión, a pesar de las mejores propiedades del sevofluorano, el isofluorano sigue siendo un anestésico de elecció n para procedimientos de corta duración en gatos.
60

Isoflurano : desenvolvimento de um método analítico empregando microextração em fase sólida, incorporação em nanoemulsões e avaliação biológica das nanoemulsões

Krahn, Carolina Lopes January 2010 (has links)
O objetivo do presente trabalho foi desenvolver e validar um método analítico empregando microextração em fase sólida (SPME) para detecção e quantificação de isoflurano (ISO) na forma volátil e incluso em nanoemulsões intravenosas e, ainda, avaliar o efeito biológico destas. A detecção do ISO foi realizada através de cromatografia em fase gasosa com detector de ionização de chama (CG/DIC). As condições ideais para realização da pré-concentração e extração de ISO através da técnica de SPME foram temperatura ambiente, agitação constante, 30 min de extração e 2 min de dessorção no injetor do CG. O método desenvolvido foi validado avaliando os parâmetros de especificidade, linearidade, limites de detecção e quantificação, precisão, exatidão e robustez. As nanoemulsões contendo ISO foram desenvolvidas através da homogeneização à alta pressão, e apresentaram diâmetro médio, índice de polidispersão, potencial zeta e pH de 150 ± 0,78 nm, 0,08 ± 0,01, - 18 ± 2,4 mV e 6,03 ± 0,04, respectivamente. O pH foi ajustado para 7,4 (valor fisiológico). O teor de ISO nas formulações foi de 98,4 %. Não houve modificação das características físico-químicas das nanoemulsões após 30 dias de armazenamento a 8 ºC. Análises de espalhamento de luz múltiplo não demonstraram tendência a fenômenos de instabilidade física para as formulações. Os estudos do efeito anestésico das nanoemulsões intravenosas contendo ISO em cães evidenciaram uma redução significativa (p < 0,05) na dose comparada com a administração de ISO volátil. Não houve alterações no débito cardíaco, saturação de oxigênio na hemoglobina e nos biomarcadores das funções renal, hepática e muscular. Uma queda na pressão arterial dos cães foi observada em todos os tratamentos devido ao efeito hipotensor do ISO. Após administração das nanoemulsões contendo ISO e branca, observou-se taquipnéia, edema, eritema, e baixas concentrações de dióxido de carbono expiradas. Assim, a nanoemulsificação do ISO foi realizada com sucesso e a aplicação na anestesia geral intravenosa foi demonstrada. / The aims of this work were to develop and validate an analytical method using solidphase microextraction (SPME) to detect and quantify isoflurane (ISO) inhalation liquid and loaded in intravenous nanoemulsions, and also evaluate the biological effect of the formulations. ISO detection was made by gas chromatography with flame ionization detector (GC/FID). The ideal conditions setting for the pre concentration and extraction of ISO through SPME were environmental temperature, constant stirring, 30 min for extraction and 2 min for analyte desorption in the GC inlet port. The developed method was validated by means of specificity, linearity, detection and quantification limits, precision, accuracy and robustness. The ISOloaded nanoemulsions were formulated by high-pressure homogenization, and presented average diameter, polydispersity index, zeta potential and pH of 150 ± 0.78 nm, 0.08 ± 0.01, -18 ± 2.4 mV and 6.03 ± 0.04, respectively. The pH was adjusted to 7.4 (physiological value). The drug content on the formulations was 98.4 %. After 30 days of storage at 8 ºC no changes on nanoemulsion’s physicalchemical characteristics were observed. Multiple light scattering analysis did not demonstrate any physical destabilization phenomena for the formulations. The anesthetic effect study for the intravenous ISO-loaded nanoemulsions in dogs highlighted a significant reduction (p < 0.05) in dosage regimen when compared to the volatile ISO administration. There were no alterations on cardiac rate, oxygen hemoglobin saturation and on biomarkers of the renal, hepatic and muscle functionalities. A decrease in dog’s arterial blood pressure in all treatments due the hypotensive effect caused by ISO was observed. After the administration of the nanomulsions, ISO-loaded and unloaded, occurred tachypnea, edema, erythema and low end tidal concentrations of carbon dioxide. Taking all above into account, the method was considered easy on execution and suitable for laboratory routines, the ISO nanoemulsification was made successfully and its application on general anesthesia was demonstrated.

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