Methadone or methadone/acepromazina: anesthetic and cardiovascular aspects in dogs

Resumo

Sedation and the effects of methadone associated or not with acepromazine on hemodynamic function and cardiac electrophysiology were compared, as well as to evidence the anesthetic feasibility of its adoption in neuroleptoanalgesia in dogs. Six dogs that received two treatments were used: methadone, 0.3 mg/kg (group M) and methadone 0.3 mg/kg associated with acepromazine 0.05 mg/kg (group MA). The following were evaluated: heart rate (HR) and respiratory rate (ƒ); systolic, diastolic and mean blood pressures (SBP, DBP and MBP, respectively); body temperature (CT); electrocardiographic and echocardiographic variables; and sedation. The evaluations were performed before and every 30 minutes after the administration of the drugs, for 120 minutes (T0, T30, T60, T90 and T120). A significant reduction in HR, ƒ, TC, SBP, DBP and MAP was observed in relation to T0 in both groups. Changes occurred in the echocardiogram in the MA group, but without clinical relevance. Ventricular escape, sinus arrest, sinus arrhythmia, left atrioventricular and anterior fascicular block, and bradyarrhythmhyma were observed in both groups. In group M, higher degrees of sedation were observed from T30 to T90 and in group MA up to T60, with no significant difference between the groups. It is concluded that, at a dose of 0.3 mg/kg, alone or associated with acepromazine, methadone promotes a sedative effect, without interference in hemodynamic function, presenting arrhythmogenic potential.