Clinical measurements performed during alfaxalone total intravenous anaesthesia for radiography and neurophysiological investigations in dogs.

Abstract

OBJECTIVE: To describe clinically relevant, physiological measurements collected during a 3 hour duration of alfaxalone total intravenous anaesthesia. STUDY DESIGN: Case series. ANIMALS: A total of 112 client-owned middle-aged or older dogs. METHODS: Dogs were premedicated with intramuscular acepromazine (0.03 mg kg). Anaesthesia was induced and subsequently maintained for up to 3 hours with alfaxalone administered intravenously. Dogs breathed 100% oxygen via an endotracheal tube. Heart rate, respiratory rate and blood pressure were evaluated 30 minutes after administration of acepromazine and used as baseline values for comparisons of intra-anaesthetic data. Blood glucose was measured 1 week prior to anaesthesia and every hour during alfaxalone anaesthesia. Quality and duration of recovery were recorded. Mean data for physiological variables were compared over three time points-before induction of anaesthesia, for the first hour of anaesthesia and from 60 minutes to discontinuation of anaesthesia. RESULTS: Mean induction dose of alfaxalone was 1.4 mg kg[95% confidence interval (CI) 1.3-1.5). Post induction apnoea for >60 seconds occurred in 13 (11.6%) dogs. Mean alfaxalone infusion rate during the first 60 minutes of anaesthesia was 0.099 mg kgminute; mean infusion rate was 0.092 mg kgminutefrom 60 minutes until discontinuation of anaesthesia. Heart rate was well maintained; hypotension (mean arterial blood pressure < 60 mmHg) was encountered in 23 (21%) dogs. Blood glucose levels did not alter during anaesthesia. Median time between discontinuation of alfaxalone infusion and extubation was 17 (7-35 minutes), time to assuming sternal recumbency was 75 (58-110 minutes), and time to standing was 109 (88-140 minutes). CONCLUSIONS AND CLINICAL RELEVANCE: Alfaxalone infusion provided effective anaesthesia in this population. In a minority of cases, respiratory and haemodynamic support of the patient was required.