Continuous paravertebral block for post-cardiothoracic surgery analgesia: a systematic review and meta-analysis

A continuous paravertebral block is used when pain relief is required beyond the duration of a single-injection paravertebral block. Surgical procedures requiring an incision into the pleural cavity are some of the most painful procedures postoperatively and, if not managed appropriately, can lead to chronic pain. The current gold standard for post-cardiothoracic surgery pain management is epidural analgesia, which has contraindications, a failure rate of up to 12% and risk of complications such as epidural abscess and spinal haematoma. This systematic review and meta-analysis aimed to investigate the use of a continuous paravertebral block for post-cardiothoracic surgery analgesia. Randomized controlled trials evaluating the continuous paravertebral block against epidural analgesia, wound infiltration, placebo or standard care (intravenous opioids) for post-cardiothoracic surgery analgesia were considered for inclusion in the systematic review. PubMed, EMBASE, The Cochrane Library and the University of York Centre for Reviews and Dissemination databases were searched from inception to 15 September 2014. Risk of bias and generalizability were assessed using a modified Downs and Black checklist. A meta-analysis was conducted on suitable studies comparing the continuous paravertebral nerve block with epidural anaesthesia, with fixed-effects models being used to pool the effects. Twenty-three randomized controlled trials with 1120 participants were included. The continuous paravertebral block was associated with a significant improvement in incidence of nausea and vomiting (odds ratio = 0.29, 95% confidence interval = [0.16, 0.56]), hypotension (odds ratio = 0.16, 95% confidence interval = [0.06, 0.41]) and urinary retention (odds ratio = 0.22, 95% confidence interval = [0.09, 0.52]) compared with the epidural block. No statistically significant difference in pain relief was reported. The continuous paravertebral block has equivalent analgesic effects to epidural analgesia, wound infiltration and standard care, but is associated with a lower incidence of nausea and vomiting, hypotension and urinary retention than epidural analgesia.