Role of preemptive epidural blockade with lignocaine, ketamine or pethidine in inhibition of anaesthetic and surgical stress response typified by levels of plasma cortisol in dogs

The present study was undertaken to evaluate the role of preemptive epidural blockade with lignocaine, ketamine or pethidine in inhibition of anaesthetic and surgical stress response in dog model of stress prepared by creation and repairing of fracture of proximal metaphysis of tibia. Twenty four dogs were allotted to four groups (I, II, III and IV) of six animals each. The fixation of fracture was done by the crosspinning and the inter-fragmentary wiring under general anaesthesia induced with atropine triflupromazine- thiopentone along with preemptive epidural blockade using lignocaine, ketamine or pethidine in groups II, III and IV, respectively. In animals of group I normal saline was given epidurally which served as control. Stress response measured was typified by levels of plasma cortisol in perioperative and postoperative period. Venous blood plasma samples were collected just before and after induction of general anaesthesia, and then after the completion of surgery and at 6, 24 and 48 hr postoperatively. Atropine-triflupromazine-thiopentone produced a significantly (P<0.05) high levels of cortisol immediately after the induction of anaesthesia in groups I, II and IV; whereas, in group III the increase was less significant. The stress response typified by high levels of cortisol could be most effectively blocked by epidural ketamine (group-III), followed in decreasing order by pethidine (group-II) and lignocaine (group-II).