There are many reports showing that a thoracic paravertebral block (TPB) can be used for post-thoracotomy pain control. However, the proper concentration of local anesthetics for TPB has not been established. The aim of this study was to define the proper concentration of bupivacaine for TPB after a thoracotomy.

Sixty patients were allocated randomly into one of the following three groups: thoracic paravertebral 0.5%, 0.25%, or 0.125% bupivacaine at a rate of 0.1 ml/kg/h (kg: ideal body weight). The resting and coughing visual analogue scale (VAS) score, cumulative dose of fentanyl, and the 5 point satisfaction scale were checked.

0.5% and 0.25% bupivacaine showed lower VAS score and cumulative dose of fentanyl than 0.125%. There was no difference in the satisfaction scale between the 3 groups. There was no difference between the 0.5% and 0.25% bupivacaine in all parameters measured.

0.25% bupivacaine used for TPB is more effective when used for pain control after a thoracotomy than 0.5% and 0.125% bupivacaine.