A research University fulfillment Medicine (in report submitted to the Faculty of Medicine, of the Witwatersrand, Johannesburg, in partial of the requirements for the degree of Master of the branch of Anaesthesia / Recognising that halothane is declining as the volatile anaesthetic agent of choice for inhalational induction and that isoflurane is replacing it, particularly in North America and Europe, this study was designed to determine whether isoflurane is comparable to halothane with respect to speed of induction and complication rate when used for rapid inhalational induction (RII) of anaesthesia. / IT2018

This thesis is concerned with the development and laboratory assessment of an electrochemical sensor for the detection and measurement of the volatile inhalation anaesthetic, forane. Investigations were therefore based on the heterogeneous and homogeneous reduction of this agent in non-aqueous electrolyte. Preliminary experiments at a mercury and other rotating disc electrodes (RDEs) revealed that the direct reduction of forane was not possible and therefore the use of an electron transfer mediator was examined. To this end, the radical anion of the polyaromatic compound, fluoranthene, (F), was investigated as a possible electro-reduction catalyst and the mediated reduction of the anaesthetic, via a catalytic process, demonstrated. Theory was presented for the calculation of chronoamperometric and steady state responses at the RDE resulting from one electron transfer and coupled (catalytic) homogeneous kinetic processes. The latter enabled a precise mechanism to be assigned to the F + forane process, while a comparison of the former theory with experimental chronoamperometric results was used, in conjunction with AC impedance studies, to investigate the adsorption of F at the mercury/acetonitrile interface. A polymer modified electrode, based on the polymer poly-(11-vinylfluoranthene) was demonstrated to be effective in the heterogeneous reduction of forane but displayed only a limited lifetime. Therefore, a Clark-type membrane electrode was constructed and the detection and measurement of forane, in the absence of oxygen, demonstrated using this device. However, the sluggish response of this sensor, together with interference problems from oxygen encouraged the development of a device which utilised a channel electrode (ChE) sensing approach. Theory was presented for the deduction of steady state currents at the ChE resulting from coupled catalytic kinetics and this was used to demonstrate that the same mechanism for the F + forane system operated at the ChE as the RDE. The conventional ChE was then modified by the incorporation of a membrane and this sensor, which was shown to operate successfully in the presence of high concentrations of oxygen and nitrous oxide, responded linearly to forane, while displaying an excellent response time of under ten seconds. The device should find application in clinical monitoring.

No description available.

Thèse (M.Sc.)--Université Laval, 2009. / Titre de l'écran-titre (visionné le 13 janvier 2010). Bibliogr.

No description available.

The effects of anaesthetic applications of isoflurane on 82 CA₁ neurons were studied in in vitro preparations (guinea pigs) using intracellular recording techniques. Various parameters of their excitability such as membrane electrical properties, action potentials and their afterhyperpolarizing potentials as well as synaptic transmission were determined during bath perfusion of clinically relevant concentrtaions of isoflurane. Concentrations of isoflurane were detected in the bath with ¹⁹fluorine nuclear magnetic resonance techniques, and were found to range between 0.02 and 0.3 mM. No consistent effects on the membrane properties were observed. When synaptic activity was blocked by tetrodotoxin, isoflurane induced a hyperpolarization (3-5 mV) without affecting input conductance which was computed from the voltage responses to injections of hyperpolarizing current pulses and the slopes of current-voltage relations for each cell. Responses to depolarizing pulses revealed that the threshold, amplitude and duration of the evoked spikes were not greatly altered, although repetitive spike firing was suppressed in a dose-dependent manner by isoflurane. Similarly, the amplitude and duration of the long-lasting hyperpolarizations following the elicitation of multiple (4 or 5) spikes were reduced in a reversible and dose-dependent manner. Reductions in amplitude and duration of excitatory and inhibitory postsynaptic potentials evoked by electrical stimulation of stratum radiatum were observed; these effects also were strictly dependent on the dose, as well as on duration of the application. These investigations have revealed that isoflurane interferes with synaptic transmission in the hippocampal slice preparation and suggest that presynaptic actions on transmitter release, in addition to postsynaptic effects / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate

Thesis (M.S.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 44-54).

Made available in DSpace on 2014-06-11T19:34:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-17Bitstream added on 2014-06-13T20:25:37Z : No. of bitstreams: 1 zambelli_fp_dr_botfm.pdf: 1509094 bytes, checksum: e6de84501fc2a502a433a545bd00c50d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Há fármacos que produzem pré-condicionamento farmacológico e, dentre estes, os anestésicos inalatórios são os mais estudados. Como exemplo, o isoflurano pode proteger o rim contra a lesão causada pela isquemiareperfusão, principalmente quando a anestesia inalatória é mantida por um período após a reperfusão. Os opióides parecem ser uma classe de fármacos capaz de produzir este pré-condicionamento. Há estudo mostrando que o remifentanil pode proteger o miocárdio contra a lesão produzida pela isquemia-reperfusão. Outro estudo mostrou que a lesão da isquemia e reperfusão renal pode ser atenuada em ratos submetidos à associação do isoflurano e do remifentanil e ao pré-condicionamento mecânico. O objetivo deste trabalho foi verificar se o isoflurano e a associação do isoflurano e do remifentanil usado após a isquemia-reperfusão podem causar proteção renal. 40 ratos machos, da raça Wistar foram distribuídos em quatro Grupos: Grupo Sham (n=10); Grupo IP (n=10), isoflurano usado durante o experimento e 90 minutos pós-reperfusão; Grupo IRP (n=10), associação do isoflurano com remifentanil usado durante o experimento e 90 minutos pós-reperfusão e Grupo Iso (n=10), isoflurano usado durante o experimento. Todos os animais foram anestesiados submetidos à intubação orotraqueal e colocados em ventilação mecânica (Ventilador Harvard Rodent 683). A veia jugular esquerda foi dissecada e um cateter foi introduzido para administração de fármacos e para a hidratação dos animais. A artéria carótida esquerda também foi dissecada e um cateter foi introduzido na sua luz com a finalidade de medida da pressão arterial (PAM) e de coleta de amostras de sangue. Todos os Grupos foram anestesiados com isoflurano na concentração inspirada entre 1,5 a 3 % e no Grupo IRP teve inicio a infusão de remifentanil na velocidade de 2 μg.kg-1.min-1. Após laparotomia... / How we can protect our patients against ischemiareperfusion injury is a question we make every day in anesthesia. Some drugs may be having the answer. Drugs can make pharmacologic preconditioning may be a good way to answer the question. Remifentanil can protect heart cells against ischemiareperfusion (IR) injury. Isoflurane can protect the kidney against IR injury. Our work makes a question if the association can make any protection against ischemiareperfusion injury? 40 male Wistar rats were put in four groups Sham (n=10), Isoflurane (n=10) (Iso), isoflurane plus wemifentanil (IRP) and isoflurane before reperfusion (ISO) with 10 rats each one. All rats groups were anesthetized and put with mechanical ventilation (Harvard Rodent Ventilator 683) by tracheal intubation. Catheters were inserted in jugular internal vein, for fluid or drug administration, and carotid artery, for measure arterial blood pressure and blood samples. All groups were anesthetized with Isoflurane between 1.5 and 3% and the group IRP start after the venous catheterize remifentanil 2 mcg/kg/min. The right kidney was removed, in the group Sham the procedure were over. For the others groups a clamp were put in left renal artery (LRA) for 45 minutes. The group Iso end, the procedure after the clamp were retired. The group IRP and IP were anesthetized for plus 90 minutes and the procedure were over. In all groups body temperature were between 36-38°C. In the end of the procedure before the extubation, analgesia were performed with infiltration of bupivacaine at 0.25%. Free food and water for all animals. After 24 hours all rats were nefrectomized in the left side and sacrificed with thiopentone. The kidneys were send to histological examination, and score for tubular lesion were performed (0- 3). Flow Cytometry (FCM) were performed in the left kidney for all groups. Blood samples to analyze serum creatinine... (Complete abstract click electronic access below)

Background: Many non-thyroidal factors affect thyroid function tests. Anesthesia and surgery have been documented to affect thyroid function tests in humans but have not been extensively studied in dogs. Hypothesis: Anesthesia alone and anesthesia combined with surgery will affect thyroid function tests in dogs. Animals: 15 euthyroid mongrel dogs. Methods: Dogs were assigned to one of three groups: control, general anesthesia, and general anesthesia plus abdominal exploratory surgery. Blood samples were collected from each dog immediately prior to pre-medication, 20 minutes after pre-medication, 55 minutes after anesthesia induction, once daily for an additional 6 days, and 14 days post-procedures. Sampling was performed at identical times in the control group. Thyroxine (T4), free T4 (fT4) by equilibrium dialysis, triiodothyronine (T3), reverse T3 (rT3) and thyroid-stimulating hormone (TSH) concentrations were measured in all samples. Results: Results of all thyroid function tests were not significantly different between control and anesthesia groups. Serum T3 for the surgery group decreased significantly from baseline compared to the control and anesthesia groups at multiple times. Serum T4 and rT3 for the surgery group increased significantly from baseline compared to the control and anesthesia groups at multiple times. Serum fT4 for the surgery group increased significantly from baseline compared to the control and anesthesia groups at 48 hours only. Conclusions and Clinical Importance: Surgery has a significant effect on thyroid function tests, while the anesthetic protocol used in this study does not. Because serum T4 and fT4 concentrations increased rather than decreased, evaluating these hormones following surgery is unlikely to lead to a misdiagnosis of hypothyroidism in euthyroid dogs. / Master of Science

Made available in DSpace on 2014-06-11T19:22:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-26Bitstream added on 2014-06-13T19:07:45Z : No. of bitstreams: 1 dessen_mr_me_botfmvz.pdf: 386204 bytes, checksum: a84656fdadfb9ae9018f3007e5844e9b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Opioides reduzem a CAM de agentes inalatórios em diversas espécies. O objetivo do presente estudo foi avaliar o efeito de três doses de sufentanil ,administradas em infusão contínua, na CAMiso em felinos. Oito gatos adultos e castrados (4.0±0.5 kg-1) foram anestesiados com isofluorano em três ocasiões distintas com um intervalo mínimo de sete dias mantidos em ventilação mecânica. A temperatura esofágica foi mantida na faixa de 38.5 a 39.0°C. Uma das três doses de sufentanil (0.01; 0.025 e 0.05 μg kg-1 minuto-1) foi selecionada aleatoriamente e infundida em cada experimento. A CAMiso basal individual, a CAMiso durante a infusões e a CAMiso após uma hora do término da infusão foram determinadas em todos os experimentos. As infusões eram feitas por 60 minutos antes da determinação da CAMISO em cada dose de sufentanil. As determinações da CAMISO foram realizadas de modo duplicado usando estímulo elétrico (50 V, frequência 50, 10 ms) aplicados nos antebraço. FC, PAS, PAM, PAD, EtCO2 e análise hemogasométrica eram registrados antes de cada determinação da CAMiso. Dados (média ± SD) foram analisados por ANOVA seguido do teste de Tukey (p<0.05%). Os valores de CAMbasal não diferiram estatisticamente (1.64±0.13; 1.61±0.24 e 1.62±0.31%). As infusões de sufentanil (0.01; 0.025 e 0.05 μg μg kg-1 minuto-1) reduziram significativamente a CAMISO 21.4±10.8; 18.5±10.5 e 18.0±13.7%, respectivamente. Não houve diferença significativa entre os valores de CAMISO durante as infusões.Os valores de CAMISO controle (1.56±0.26; 1.50±0.22 e 1.53±0.26%) foram inferiores da CAMISO basal indicando um possível efeito residual do opioide após a descontinuação da infusão. Os valores de FC e das pressões arteriais aumentaram durante as infusões de sufentanil 0.025 e 0.05 μg kg-1 minuto-1. As três doses de sufentanil infundidas resultaram em graus semelhantes... / Opioids reduce the MAC of Inhalants agents in many species. The aim of this study was to evaluate the effects of three sufentanil constant rate infusions (CRIs) on the MACISO in cats. Eight adult spayed cats (4.0±0.5 kg-1) were anesthetized with isoflurane under mechanical ventilation on three occasions with a minimum 7-day interval between. Esophageal temperature was maintained within a narrow range (38.5 to 39.0°C). One of three sufentanil CRIs (0.01; 0.025 and 0.05 μg kg-1 minute-1) was randomly selected to be administered on each day of MACISO determinations. On all study days, the individual basal MACISO (MACbasal), the MACISO during one of the infusion rates, and the control one hour post-infusion MAC (MACcontrol) were determined. CRI was continued for 60 minutes before MACISO was determined for each sufentanil dose. The MACISO determinations were performed in duplicate using an electrical stimulus (50V, 50 cycles second-1, 10 ms) applied to the antebrachium. HR, SAP, MAP, DAP, ETCO2, and arterial blood gases were recorded before and after each MACISO determination. Data (mean±SD) were compared by ANOVA followed by Tukey’s test (p<0.05%).MACbasal values were not significantly different (1.64±0.13; 1.61±0.24 and 1.62±0.31%). Sufentanil CRIs (0.01; 0.025 and 0.05 μg kg-1 minute-1) significantly reduced MACISO by 21.4±10.8; 18.5±10.5 and 18.0±13.7%, respectively. There were no significant differences between the MACISO values determined during the CRIs. The MACcontroll values (1.56±0.26; 1.50±0.22 and 1.53±0.26%) were different from MACbasal indicating the possibility of a residual opioid effect after the discontinuation of infusions. HR and blood pressure values increased during infusion of the higher sufentanil CRIs (0.025 and 0.05 μg kg-1 minute-1). The three CRI doses of sufentanil resulted in similar degrees of MACISO reduction in cats, indicating that... (Complete abstract click electronic access below)