Avaliação dos efeitos hemodinâmicos, respiratórios, metabólicos e sedativos da dexmedetomidina isolada ou associada à tiletamina-zolazepam em cães. Estudo experimental / Hemodinamic, respiratory, metabolic and sedative effects evaluation of dexmedetomidine alone or associated with tiletamine-zolazepam in dogs. Experimental study

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The aim of the present study was to evaluate hemodynamic, respiratory and metabolic alterations, the quality of induction and recovery of the animal, as well as sedation and muscular relaxation promoted by the use of dexmedetomidine alone or associated to tiletamine-zolazepam. Eighteen healthy male and female mongrel dogs were used and randomly assigned to two groups: group I animals were treated with dexmedetomidine (10 mcg.kg-1 i.m.) and after 20 minutes, saline solution (0,06 ml.kg-1 i.v.); group II animals received the same dose of dexmedetomidine and after 20 minutes, tiletamine-zolazepam (6,0 mg.kg-1 i.v.). Data were collected immediately before dexmedetomidine application and after five, 15, 25, 40, 55 and 85 minutes of the dexmedetomidine administration. Data were submitted to Analysis of Variance Test followed by Tukeys, non parametrics datas were evaluated with Mann-Whitney "U" test, with 5% of significance (p <0,05). In group I was observed gradual reduction of the heart rate, cardiac output and the cardiac index after the use of dexmedetomidine. In group II there was similar reduction, but in less magnitude after tiletamine-zolazepam administration. The pulmonary capillary wedge pressure, as well as central venous pressure and systemic vascular resistance index increased significantly in relation to baseline values in both groups. The sistolic, diastolic and mean arterial pressure increased after application of tiletamine-zolazepam. There was a mild respiratory depression only in group II, with the reduction of the arterial partial pressure of oxygen and increase in the the arterial partial pressure of carbon dioxide values. In both groups the reduction of the mixed venous blood partial pressure of oxygen and mixed venous blood saturation of oxygen was observed, this decrease was more intense in group I. The oxygen transport index reduced up to 44% and 50% in the groups I and II, respectively, however the values of oxygen consumption and extraction maintained next to baseline values. There was ventilatory depression with reduction of volume minute and alveolar volume minute in group I; tidal volume and tidal volume alveolar in group II. In terms of induction quality, there was no excitation, vocalization and paddling of limbs in group II, and recovery presented no incoordenation and muscular hypertonus in both group. The sedation promoted by dexmedetomidine was appropriated allowing lateral recumbency, with ability to rise the head in 78% of the animals. In group II a profound sedation level was obtained after tiletamine-zolazepam administration. The muscular relaxation was adequated, varying from moderate to intense in both of the groups. In view of the obtained results it was possible to conclude that: dexmedetomidine promoted important reduction of heart rate and of all other cronotropism dependent hemodynamic parameters; when dexmedetomidine was associated to tiletamine-zolazepam, reduction of heart rate was in less magnitude ; dexmedetomidine i.m. preserved the pressure parameters probably due to increase of systemic vascular resistance index; dexmedetomidine i.m. developed a mild respiratory depression and promoted moderate to profound level of sedation and moderate to intense level of muscular relaxation.

ASSUNTO(S)

cães dogs anestésicos dissociativos sedativos dissociative anesthetic sedative

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