Metabolic and hemodynamic evaluation of two long term sedation protocols in dogs

ABSTRACT

We aimed to determine the hemodynamic and metabolic parameters of two sedative protocols for long-term ventilation in dogs. Twelve dogs, were randomly allocated in two groups (n=6) who received constant rate infusion (CRI) of midazolam (0,5mg/kg/h), fentanyl (10µg/kg/h) and propofol (18mg/kg/h) in GMF or ketamine (0,6 mg/kg/h), morphine (0,26mg/kg/h) and propofol (18mg/kg/h) in GCM, during 24 hours. The dogs were mechanically ventilated to normocapnia with FiO₂ of 40%. Heart rate decreased 32% in GMF and 34% in GCM during infusion time reducing CI in 24% at GMF and 29% at GCM. CaO₂, CmvO₂, DO₂ and VO₂ decreased in GCM (5%, 16%, 31% and 7% respectively) and GMF (4%, 19%, 26% and 15% respectively). Extraction ratio increased 32% in GMF and 36% in GCM without differences between groups; however, decreased VO₂, evaluated for indirect calorimetry, suggests minimization of DO₂ reduction. No differences between time to extubation, sternal recumbency and total recovery time were observed between groups, with an average of 33,8±15,9, 134,8±60,7 e 208±77,5 minutes respectively. We conclude that both protocols allowed mechanical ventilation with IC and DO₂ reduction without metabolic and hemodynamic impairment, and can be safely used in healthy dogs.

Keywords:
mechanical ventilation; propofol; ketamine; midazolam; opioids