Intercostal thoracotomy is a very painful procedure that deserves proper prevention and treatment. In this study we aimed to investigate the cardiovascular effect of the association of tramadol, butorphanol and atropine in the premedication of cats anesthetised with propofol and halothane. Twelve cats of mixed breed, female and male, with mean body weight of 2.7 ± 0.62kg were premedicated with 2.0mg kg-1 tramadol and 0.4mg kg-1 butorphanol and 0.044mg kg-1 atropine combined in the same syringe intramuscularly administered. After 30 minutes of premedication, anesthetic induction was obtained with 5.0mg kg-1 propofol intravenously. Anesthetic maintenance was done with halothane and 100% oxygen with manual artificial ventilation. All cats were submitted to lateral intercostal thoracotomy for an autogenic pericardium graft implantation in the diaphragm. Variables studied were heart rate (bpm), hemoglobin oxygen saturation (%), systolic arterial pressure (mmHg), and halothane vaporization (%). Time for data collection were 20 minutes after premedication (TMPA), 10 minutes after induction and every 10 minutes up to the end of the surgical procedure (T10 to T100). Data were analyzed with ANOVA and Bonferroni's test (p<0.05). Results demonstrated statistically significant reduction in arterial systolic pressure and heart rate, however, kept within the physiologic variation parameter to felines. Hemoglobin oxygen saturation was close to 100% in all times. Halothane vaporization decreased significantly from T30 to T100, staying for most of the surgical time below the minim alveolar concentration for cats. In conclusion the assotiation tramadol (2.0mg kg-1), butorphanol (0.4mg kg-1) and atropine (0.044mg kg-1) in the premedication of cats anesthetised with propofol (5.0mg kg-1) and halothane, intramuscularly, produces minimal changes cardiovasculares, don't produce sedation and promote analgesia satisfactory for lateral intercostal thoracotomy.
cats; thoracotomy; tramadol; butorphanol
