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Master's Dissertation
DOI
10.11606/D.10.2006.tde-06032007-151544
Document
Author
Full name
Sérgio dos Santos Souza
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2006
Supervisor
Committee
Cortopassi, Silvia Renata Gaido (President)
Fantoni, Denise Tabacchi
Futema, Fábio
Title in Portuguese
Efeitos da dexmedetomidina, por via epidural ou infusão contínua intravenosa, em gatas anestesiadas com propofol e isofluorano e submetidas a ovariossalpingohisterectomia
Keywords in Portuguese
dexmedetomidina
epidural
gatos
infusão contínua
Abstract in Portuguese
Este estudo determinou e comparou os efeitos da administração epidural ou infusão contínua intravenosa de dexmedetomidina em gatas anestesiadas com propofol e isofluorano para realização de ovariossalpingohisterectomia. Vinte e uma gatas (peso: 3.06±0.35 kg) foram pré-tratadas com dexmedetomidina (4 mcg.kg-1, IM). Quinze minutos depois, administrou-se propofol para permitir entubação orotraqueal seguido de manutenção anestésica com isofluorano diluído em oxigênio por um circuito Mapleson D com respiração espontânea. As gatas foram distribuídas aleatoriamente, em três grupos, onde receberam, por via epidural, lidocaína (1 mg.kg-1, G1, n=7) ou lidocaína (1 mg.kg-1) + dexmedetomidina (4 mcg.kg-1, G2, n=7) ou lidocaína (1 mg.kg-1) + infusão contínua intravenosa de dexmedetomidina (0,25 mcg.kg-1.min-1, G3, n=7). O volume da solução para administração epidural foi ajustada para 0.3 mL.kg-1 com solução salina. A profundidade anestésica foi realizada por um único avaliador que não possuía conhecimento dos fármacos empregados pela via epidural e intravenosa. Foram mensurados freqüência cardíaca (FC) e respiratória (FR), pressão arterial sistólica (PAS) e temperatura retal (TR) antes e quinze minutos após a medicação pré-anestésica. Durante a anestesia, FC, FR, pressões arteriais, concentração expirada de CO2, concentração expirada de isofluorano (ISOe), TR e grau de relaxamento muscular foram avaliados em intervalos de 15 minutos de 20 até 80 minutos. A hemogasometria foi realizada aos 20 e 80 minutos após a indução anestésica. Os valores de FC, FR, TR, escore de analgesia, qualidade e os tempos de recuperação anestésica foram avaliados por três horas após o término da anestesia. Utilizou-se o teste t pareado para avaliar os efeitos do pré-tratamento e os valores hemogasométricos nos dois momentos. O teste análise de variância seguido de Tukey e Friedmann seguido de Dunn foram realizados para variáveis paramétricas e não paramétricas respectivamente (p<0.05). O pré-tratamento com dexmedetomidina reduziu a FC, FR, PAS e TR. A dose de propofol utilizada para indução anestésica foi 7.4±1.4 mg.kg-1. Quando comparado ao G1, a dexmedetomidina, por via epidural, reduziu significativamente a FC dos 20 aos 65 minutos da anestesia e aos 150 e 180 minutos após o término da anestesia, entretanto, por infusão contínua intravenosa reduziu a FC em todos os momentos avaliados da anestesia e recuperação anestésica. Quando comparado ao G2, a infusão contínua intravenosa de dexmedetomidina reduziu a FC aos 60 e 90 minutos da recuperação anestésica. No G1 a média±DP ISOe variou de 0.86±0.28% a 1.91±0.63% de 20 a 80 minutos. Neste período, ISOe foi significativamente menor no G2 (variação de 0.70±0.12% a 0.97±0.20%) e G3 (variação de 0.69±0.12% to 1.17±0.25%). Aos 20 minutos, a PaCO2 foi significativamente superior em G3 em relação ao G1. Os tempos de recuperação anestésica foram significativamente menores no G1, exceto o tempo de extubação se comparado ao G2. Não houve diferença significativa nas outras variáveis entre os três grupos. Conclui-se que o pré-tratamento com dexmedetomidina promoveu depressão cardiorrespiratória. A administração epidural e a infusão contínua intravenosa de dexmedetomidina reduziram o consumo do agente inalatório e produziram recuperação de melhor qualidade e mais prolongada. As administrações de dexmedetomidina causaram bradicardia, porém sem afetar a pressão arterial.
Title in English
Effects of dexmedetomidine by epidural or continuous intravenous infusion in cats undergoing propofol-isoflurane anesthesia to ovariohysterectomy
Keywords in English
cats
continuous infusion
dexmedetomidine
epidural
Abstract in English
This study compared the effects of epidural or continuous intravenous infusion of dexmedetomidine in isoflurane-anesthetized cats undergoing ovariohysterectomy. Twenty-one cats (weight: 3.06±0.35 kg) were premedicated with dexmedetomidine (4 mcg.kg-1, IM). Fifteen minutes later, propofol was titrated to allow endotracheal intubation and anesthesia was maintained in spontaneously breathing cats with isoflurane in oxygen using a Mapleson D system. Cats were randomly allocated to receive either epidural lidocaine (1 mg.kg-1, G1, n=7) or epidural lidocaine (1 mg.kg-1) + dexmedetomidine (4 mcg.kg-1, G2, n=7) or epidural lidocaine (1 mg.kg-1) + continuous intravenous infusion of dexmedetomidine (0,25 mcg.kg-1. min-1, G3, n=7). The volume of either epidural injection was adjusted to 0.3 mL.kg-1 with saline. The individual controlling depth of anesthesia was blinded to the drug being administered epidurally and intravenouslly. Heart (HR) and respiratory (RR) rates, systolic arterial blood pressure (SAP) and rectal temperature (RT) were recorded before and after 15 minutes of premedication. During anesthesia, heart (HR) and respiratory (RR) rates, invasive arterial blood pressures, end-tidal CO2, end-tidal isoflurane (ISOe), RT and muscular relaxation were recorded at 15 minute intervals from 20 until 80 minutes. Arterial blood gases were measured at 20 and 80 min after induction. HR, RR, RT, analgesia score, and recovery quality and times were compared for 3 hours after end of anesthesia. Paired t test were performed to compare the premedication effects and arterial blood gases at differents intervals. ANOVA with Tukey post-test and Friedmann with Dunn post-test were performed to parametric and nonparametric values, respectively (P<0.05). Dexmedetomidine premedication decreased HR, RR, SAP and RT. The induction dose of propofol was 7.4±1.4 mg.kg-1. When compared to the G1, epidural dexmedetomidine significantly decreased HR from 20 to 65 minutes of anesthesia and 150 and 180 minutes after end of anesthesia, however, continuous intravenous infusion decreased HR all times during anesthesia and recovery time. When compared to G2, continuous intravenous infusion of dexmedetomidine decreased HR at 60 and 90 minutes during recovery. In the G1 mean±SD ISOe concentrations ranged form 0.86±0.28% to 1.91±0.63% from 20 to 80 min. At the same time interval, ISOe concentrations were significantly lower in the G2 (ISOe ranged from 0.70±0.12% to 0.97±0.20%) and G3 (ISOe ranged from 0.69±0.12% to 1.17±0.25%). PaCO2 was significantly greater in G3 than G1 at 20 minutes. The recovery times were significantly lower in the G1 except for extubation time when compared with G2. There were no significant differences among groups for the remaining variables. It was concluded that premedication with dexmedetomidine produced cardiorespiratory depression. Epidural administration and continuous intravenous infusion of dexmedetomidine significantly reduced inhalant requirements for maintaining anesthesia and produced a better anesthesia recovery although of longer duration. Dexmedetomidine administration may cause bradycardia, however reduced HR does not affect arterial blood pressure.
 
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SergiodosSantosSouza.pdf (578.08 Kbytes)
Publishing Date
2007-03-09
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • Souza, Sérgio S, et al. Cardiopulmonary and isoflurane-sparing effects of epidural or intravenous infusion of dexmedetomidine in cats undergoing surgery with epidural lidocaine [doi:10.1111/j.1467-2995.2009.00512.x]. Veterinary Anaesthesia and Analgesia [online], 2010, vol. 37, p. 106-115.
  • SOUZA, Sergio dos Santos, et al. Evaluation of epidural dexmedetomidine combined with lidocaine in isoflurane anesthetized cats undergoing surgery. In 9th Congress of Veterinary Anaesthesiology, Santos/SP, 2006. Congress Proceedings., 2006. Abstract.
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