Comparative evaluation of midazolam-ketamine-xylazine and propofol-ketamine combinations for maintenance of anaesthesia by constant rate infusion in canine: haemodynamic study

The present study was undertaken to evaluate the haemodynamic effects of two anaesthetic protocols in two groups (A and B) of healthy bitches (n=10 each), which underwent oophorectomy by conventional or laparoscopic method. Each group was subdivided into 2 subgroups (A₁, A₂and B₁, B₂) each containing 5 animals. The animals of all four subgroups received glycopyrrolate (0.005 mg/kg b.wt) and followed, 10 min later, by xylazine (0.5 mg/kg b.wt) intramuscularly as preanaesthetic medication. After 10 min of the administration of preanaesthetics, induction of anaesthesia was achieved by administering midazolam (0.2 mg/kg b.wt) and ketamine (5.0 mg/kg b.wt) i.v., till effect. After 5 min of induction, the maintenance of anaesthesia was started with midazolam (0.4 mg/kg/hr)-ketamine (20 mg/kg/hr)-xylazine (1.0 mg/kg/hr) in animals of subgroup A₁ and B₁, while propofol (3.6 mg/kg/hr)-ketamine (5.4 mg/kg/hr) was used in animals of subgroups A₂ and B₂ as constant rate infusion (CRI) using an infusion pump. Haemodynamic study included estimation of ECG, SpO₂, and MAP at base line, maximum depth of sedation, 5 min after anaesthetic induction, middle of maintenance and at complete recovery of drug administration. These parameters changed within physiological limits at different intervals and nearly normalized at complete recovery, indicating nonsignificant alteration in body systems in animals of all subgroups.