Minimum alveolar concentration of isoflurane in dogs administered two morphine doses/Concentracao alveolar minima do isoflurano em caes tratados com duas doses de morfina

• Published in: Ciência rural Vol. 47; no. 11
• Main Authors: Coelho, Karina, Monteiro, Eduardo Raposo, Bressan, Thais Feres, Monteiro, Betania Souza, Campagnol, Daniela, Alievi, Marcelo Meller
• Format: Journal Article
• Language: English
• Published: Universidade Federal de Santa Maria 01-11-2017
• Subjects: Brasil
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20170132

This study aimed to evaluate the effects of intramuscular 0.5mg [kg.sup.-1] ([MOR.sub.0.5] and 1.0mg [kg.sup.-1] ([MOR.sub.1.0]) morphine premedication on the minimum alveolar concentration of isoflurane ([ISO.sub.MAC]) in dogs. Eighteen client-owned female dogs were scheduled for elective ovariohysterectomy. Dogs received intramuscular [MOR.sub.0.5] or [MOR.sub.1.0] as premedication and propofol IV for induction of anesthesia. Isoflurane was delivered for maintenance of anesthesia and dogs were maintained under normocapnia and normothermia. Determinations of the [ISO.sub.MAC] were conducted by use of the "up-and-down" method. Noxious stimulus (placement of Backhaus towel clamps, a midline skin incision and subcutaneous tissue dissection) was delivered approximately 50 minutes after premedication with [MOR.sub.0.5] or [MOR.sub.1.0]. The calculated [ISO.sub.MAC] was 0.98 [+ or -] 0.15% in [MOR.sub.0.5] and 0.80 [+ or -] 0.08% in [MOR.sub.1.0]g. The [ISO.sub.MAC] was significantly lower in [MOR.sub.1.0]0 compared with [MOR.sub.0.5] (P=0.010). Results of this study suggested that intramuscular premedication with morphine 0.5 and 1.0mg [kg.sup.-1] decreases the [ISO.sub.MAC] in a dose-related manner in dogs. Key words: autonomic response, canine, inhalational anesthetics, opioids. O presente estudo objetivou avaliar os efeitos da administracao intramuscular de 0,5mg [kg.sup.-1] ([MOR.sub.0.5]) ou 1,0mg [kg.sup.-1] ([MOR.sub.1.0]) de morfina sobre a concentracao alveolar minima do isoflurano ([CAM.sub.ISO]) em caes. Dezoito cadelas de proprietarios foram agendadas para ovario'histerectomia eletiva. As cadelas receberam [MOR.sub.0.5] ou [MOR.sub.1.0], como medicacao pre-anestesica, e propofol IV para inducao da anestesia. A manutencao da anestesia foi realizada com isoflurano em condicoes de normocapnia a normotermia. A determinacao da [CAM.sub.ISO] foi conduzida de acordo com o metodo "up-and-down". O estimulo nociceptivo (colocacao de pincas Backhaus, incisao da pele na linha media e disseccao de tecido subcutaneo) foi realizado aproximadamente 50 minutos apos a administracao de [MOR.sub.0.5] ou [MOR.sub.1.0]. A [CAM.sub.ISO] calculada foi 0,98 [+ or -] 0,15% em [MOR.sub.0.5] e 0,80 [+ or -] 0,08% em MORig. A CAM1OO foi significativamente menor em [MOR.sub.1.0]0 do que em [MOR.sub.0.5] (P=0,010). Os resultados do estudo sugerem que a medicacao pre-anestesica com morfina nas doses de 0,5 e 1,0mg [kg.sup.-1], pela via intramuscular, resulta em reducao dose~dependente na [CAM.sub.ISO] em caes. Palavras-chave: resposta autonomica, canino, anestesicos inalatorios, opioides.