The importance of pleural integrity for effective and safe thoracic paravertebral block: a retrospective comparative study on postoperative pain control by paravertebral block.

OBJECTIVES Recently, paravertebral block (PVB) has been reported to be an effective analgesic modality for post-thoracotomy pain, but there is no consensus on how thoracic PVB can be more effective. Our hypothesis that intact pleura has a significant impact on the analgesic effectiveness of thoracic PVB was evaluated. METHODS Data of patients who underwent general thoracic surgery [thoracotomy or video-assisted thoracic surgery (VATS)] and paravertebral catheterization at Nagara Medical Center between April 2010 and March 2013 were collected. To compare the frequency of non-steroidal anti-inflammatory drugs taken as well as the usage of rescue pain medications between patients with pleural disruption and those without, data were analysed after matching on propensity scores. Covariates for match estimation were age, sex, body mass index, American Society of Anesthesiologists score, diagnosis, operative details and local anaesthesia infused. RESULTS There were 278 patients who underwent general thoracic surgery and paravertebral catheterization. The propensity score-matching process created 78 matched patients with pleural disruption and those without. Based on the propensity score matching, a significant increase in the frequency of non-steroidal anti-inflammatory drugs taken on postoperative day 1 and in the usage of rescue drugs was observed in patients with pleural disruption. CONCLUSIONS According to our analysis, creating a sub-pleural space without pleural disruption is essential for quality thoracic PVB.