Haemodynamic effects of subarachnoid blockade: 20% lignocaine versus 0.5% plain bupivacaine.

BACKGROUND

Our study compared the haemodynamic changes after spinal anaesthesia with 2% lignocaine and 0.5% plain bupivacaine.

METHODS

A controlled, randomized trial was performed on 30 patients scheduled for arthroscopic knee surgery. Two percent lignocaine and 0.5% plain bupicacaine was used for spinal anesthesia. We measured cardiac output, blood pressure and level of sensory blockade before and for 25 minutes after spinal anaesthesia.

RESULTS

In patients developing sensory block below T6 there were no differences between the study drugs in heamodynamic measurements. In patients who developed a sensory block at or above T6 there was a greater drop in mean arterial pressure and cardiac output and a faster decrease in heart rate in patients receiving bupivacaine.

CONCLUSION

In patients developing a sensory block at or above the T6 dermatome, the decrease in cardiac output and mean arterial pressure in the first 25 min. after spinal anaesthesia is smaller if 2% lignocaine rather than 0.5% bupivacaine is used for blockade.