Low-dose ketamine combined with pentobarbital in a miniature porcine model for a cardiopulmonary bypass procedure: a randomized controlled study

Abstract

Porcine anaesthesia remains a great problem for cardiac surgery research and especially with cardiopulmonary bypass procedures. This study was designed to develop a suitable anaesthesia model in which miniature pigs could be induced smoothly and be maintained stably during and after a cardiopulmonary bypass procedure. Thirty-one miniature pigs were randomly divided into two groups and induced using ketamine and pentobarbital (K-P group, n = 15) or pentobarbital (P group, n = 16) alone, respectively. Animals in group K-P were induced with intramuscular injections of ketamine 5 mg kg and pentobarbital 20 mg kg body weight, and those in group P were induced with pentobarbital 30 mg kg alone. After intubation and intravenous catheterization, group K-P was maintained by continuous infusion of ketamine and pentobarbital, and pentobarbital was withdrawn after cardiopulmonary bypass started. Group P received a continuous infusion of pentobarbital throughout the operation. In addition, both groups were injected hourly with midazolam and pipecuronium bolus to achieve optimal surgical conditions. All of the group K-P animals survived for 24 h postoperatively. Five of the group P animals died from anaesthesia-related respiratory and cardiac arrest: three after induction and two after extubation. The animals in group K-P had more stable haemodynamics and arterial blood gas indices than animals in group P. Furthermore, the percentage of animals achieving satisfactory anaesthetic effects was significantly higher in group K-P than in group P. Combination anaesthesia with low-dose ketamine and pentobarbital demonstrated superior haemodynamic and respiratory indices in comparison with pentobarbital. The combination regimen can achieve both hypnosis and analgesia effects with stable circulatory parameters.