Effects of combined midazolam and propofol in anesthesia induction and recovery of cats undergoing ovariohisterectomy

Abstract

The objective of this study was to determine the effects of propofol and midazolam on induction of anesthesia in cats undergoing ovariohysterectomy, measured in terms of the quality of tracheal intubation, anesthesia induction, cardiorespiratory effects, and recuperation period. Thirty healthy adult cats were pretreated with acepromazine and morphine. After 30 min, they were divided into three groups: PG (n = 10), in which induction was performed with only intravenous propofol at doses required for intubation; MPG (n = 8), in which animals received intravenous midazolam (0.3 mg kg -1 ) administered over 30 s, followed by administration of propofol as in PG; and PMG (n = 9), in which propofol was first administered at a rate of 4 mg kg -1 min -1 , after which midazolam was administered (0.3 mg/kg), followed by re-administration of propofol. In order to perform a blinded study, the PG and PMG received a 0.9% NaCl solution volume similar to the midazolam dose before induction (0.06 mL/kg). Similar to the other groups, the PG and MPG received (0.06 mL kg -1 ) saline 30 s after administration of propofol. In order to mimic the administration of midazolam, the saline solution was administered for 30s. The PG received 11.0 ± 1.38 mg kg -1 propofol, a greater dose than that administered to the PMG (p < 0.001) and MPG (p < 0.01), which received 7.9 ± 1.92 and 9.1 ± 2.20 mg kg -1 , respectively. There were no differences in the intubation scores between groups. Previous use of midazolam did not affect agitation or excitement in cats; both sequences of propofol-midazolam administration are feasible, but the propofol-midazolam sequence was superior due to the lower propofol dose. Key words: Benzodiazepines, castration, dogs, feline ResumoO objetivo deste estudo foi determinar os efeitos de propofol e midazolam na indução da anestesia em gatas submetidas a ovariossalpingohisterectomia quanto a qualidade da intubação orotraqueal e da indução da anestesia, efeitos cardiorrespiratórios e períodos de recuperação. Foram utilizadas 27 gatas adultas e hígidas que foram pré-tratadas com acepromazina e morfina. Decorridos 30 minutos, foram distribuídas em três grupos: no GP (n=10), a indução foi realizada somente com propofol por via intravenosa na dose necessária para intubação orotraqueal; no GMP (n=8), os animais receberam midazolam (0,3 mg/kg) administrado pela via intravenosa em 30s, e em seguida o propofol foi administrado segundo os critérios do grupo propofol; no GPM (n=9), administrou-se, inicialmente, propofol na velocidade de 4 mg/kg/min; posteriormente, administrou-se midazolam (0,3 mg/kg), e o restante da indução foi realizado com propofol. Para que o estudo fosse cego, os animais dos grupos GP e GPM receberam solução salina no volume similar à dose de midazolam antes da indução (0,06 ml/kg). Da mesma forma, os grupos GP e GMP receberam solução de NaCl a 0,9% (0,06 ml/kg) após 30s de administração de propofol. Com objetivo de mimetizar a administração do midazolam, a solução salina foi administrada em 30s. O GP r...