Incidence of intraoperative hypotension during isoflurane–fentanyl and propofol–fentanyl anaesthesia in dogs

Most anaesthetic and analgesic drugs affect the cardiovascular system and can cause intraoperative hypotension (IOH). This study aimed to compare the incidence of IOH in anaesthetised dogs when isoflurane–fentanyl was used, compared to propofol–fentanyl. Intraoperative hypotension was defined as an episode of mean blood pressure below 60 mmHg for more than 5 min during anaesthesia. The incidence of IOH was 65.3% for isoflurane–fentanyl and 27.6% for propofol–fentanyl. The adjusted odds ratio for IOH when propofol–fentanyl was compared to isoflurane–fentanyl was 0.2 (95% CI 0.11–0.38). These results suggest that propofol–fentanyl is associated with a lower risk of IOH than isoflurane–fentanyl anaesthesia.