Haemodynamic stability during balanced total intravenous anaesthesia using fentanyl-propofol co-induction and maintenance with constant rate infusion of dexmedetomidine-fentanyl-lignocaine-ketamine along with variable rate infusion of propofol in dexmedetomidine-midazolam-ketamine premedicated dogs

Abstract

The study was conducted in ten apparently healthy adult dogs of varying ages and gender presented for various elective surgeries, categorised as ASA class I or II. After premedication with meloxicam (@ 0.2 mg/kg), all the animals were sedated with dexmedetomidine (@ 2 mcg/kg), midazolam (@ 0.2 mg/kg), and ketamine (@ 3 mg/kg) given intravenously. Upon sedation, co-induction was done intravenously using fentanyl (@ 5 mcg/kg) followed by propofol administered “to effect”. After intubation and oxygen supplementation, lignocaine (@ 2 mg/kg) was given as a loading dose. Anaesthesia was maintained using a constant rate infusion (CRI) of dexmedetomidine (@ 2 mcg/kg/h), fentanyl (@ 5 mcg/kg/h), lignocaine (@ 50 µg/kg/min), and ketamine (@ 40 µg/kg/min) along with a variable rate infusion of propofol, titrated as needed.Sedation was achieved within 2.10±0.46 minutes, and anaesthetic maintenance lasted between 86 and 239 minutes. Recovery was smooth in 90% of cases, occurring within 13.30±3.84 minutes after cessation of CRIs. Profound muscle relaxation, analgesia, and unconsciousness were achieved. A transient reduction in heart rate, respiratory rate, and blood pressure was observed post-induction, but mean arterial blood pressure remained adequate for tissue perfusion. In five animals with post induction apnoea, fluctuations in the end-tidal carbon dioxide (ETCO₂) and tidal volume indicated respiratory depression, necessitating assisted ventilation. Haematology, serology, and blood gas analyses showed no post-anaesthetic abnormalities, with improved organ perfusion markers.