Prolonged pharmacokinetic simulator-assisted propofol total intravenous infusion in a cat undergoing thoracic duct ligation.

This case report describes the use of total intravenous anesthesia with propofol and dexmedetomidine for 5 hours in a cat undergoing thoracic duct ligation revision surgery for persistent chylothorax. Following intravenous (IV) premedication with methadone (0.2 mg kg), general anesthesia was induced with IV propofol (2 mg kg) and ketamine (2 mg kg). For maintenance of anesthesia, dexmedetomidine was given as constant rate infusion (1 μg kg hour), while a free web-based application was used to predict propofol plasma concentration (PPC) in real-time. Ultrasound-guided left erector spinae plane blocks were performed preoperatively at thoracic vertebrae 11 and 13, injecting bupivacaine (1.5 mg kg site) and dexmedetomidine (1.7 μg kg site). Propofol infusion rates were manually reduced at anesthetist discretion to achieve reductions in predicted PPC of 0.5-1 μg mL if no response to surgery was observed. During anesthesia (from tracheal intubation to propofol discontinuation), the propofol infusion rate ranged from 0.066 to 0.2 mg kg minute, and the mean predicted PPC recorded during anesthesia was 4.23 ± 0.68 μg mL (mean ± standard deviation). Intraoperatively, heart rate, mean arterial blood pressure, and end-expiratory partial pressure of carbon dioxide were 128 ± 7 beats minute, 76 ± 10 mmHg, and 34 ± 5 mmHg (4.53 ± 0.67 kPa), respectively. No additional intraoperative analgesics were given. Recovery from general anesthesia was uneventful and the trachea was extubated 10 minutes after discontinuing dexmedetomidine and propofol (predicted PPC 2.3 μg mL). The real-time PPC predictions enabled precise propofol titration, ensuring hemodynamic stability while minimizing drug accumulation and promoting rapid recovery.