A systematic review of comparative studies indicates that paravertebral block is neither superior nor safer than epidural analgesia for pain after thoracotomy

Abstract

Background The “gold standard” for pain relief after thoracotomy has been thoracic epidural analgesia (TEA). The studies comparing TEA with paravertebral block (PVB) and recent reviews recommend PVB as a novel, safer method than TEA. Methods A systematic search of the Cochrane and PubMed databases for prospective, randomized trials (RCTs) comparing TEA and PVB for post-thoracotomy analgesia was done. We assessed how TEA and PVB were performed, methods of randomization, assessment of pain relief, and complications. Abstracts only were excluded. Results Ten studies were included, comprising 224 patients randomized to TEA, 243 to PVB. The studies were heterogeneous. Therefore, a systematic narrative review with our evaluations is presented. Only 3/10 trials reported the method of randomization. Pain during coughing was reported in only 5/10, pain assessment not specified in 5/10. Only 1/10 trials found PVB superior to TEA, but placed TEA catheters too low (<T7). TEA was superior to PVB in 1/10, during first 1.5 days. PVB and TEA were equally effective in 8/10. 5/10 trials found PVB had less hypotension or urinary retention. None of the studies used appropriate and optimal TEA: TEA was started after end of surgery in half, catheters placed too low (2/10), too high (1/10), not reported in (1/10). 7/10 infused local anaesthetic only, 2/10 added fentanyl, 1/10 added morphine, and none added adrenaline. PVB infusions had higher concentration of bupivacaine (5 mg/ml) in 2/10, 1/10 added fentanyl, 1/10 added ornipressin. Loading doses were higher in 5/10, and with more concentrated solutions in 5/10 of PVB than in the TEA group. Conclusions 10 heterogeneous, mostly small, studies comparing TEA and PVB for post-thoracotomy analgesia do not allow conclusions on which method has superior analgesic efficacy and safety. The main methodological problem was that none of the studies use optimal thoracic epidural analgesia, with siting of catheters inappropriate in some and the epidural infusion containing too concentrated local anaesthetic because opioid and adrenaline were not added. Anatomical considerations (the paravertebral space comprises parts of the epidural space and contains spinal cord arteries) and personally experienced complications with PVB (paraplegia) convince us that PVB must have higher risk of, infrequent but serious, spinal cord complications than TEA. Percutaneous PVB may puncture pleura and lung. Some surgeons expressed satisfaction with PVB because the method omits costly acute pain services for monitoring on surgical wards and saves time in the operating room. They are, however, bound to experience serious complications from PVB, sooner or later. To our knowledge, optimally conducted epidural analgesia has not been compared with PVB. Current literature and our experience with both techniques for up to four decades, indicate that PVB may be an alternative for post-thoracotomy pain when TEA is infeasible for various patient-related reasons ( Breivik et al., 2009). Severely disturbed haemostasis is a contraindication for PVB and TEA. Higher concentrations of local anaesthetics are needed to obtain intercostal nerve blocks and epidural analgesia with PVB, risking local anaesthetic intoxication. Robust monitoring regimen for effects and adverse effects is as important for PVB as for TEA.