Abstract: We included 14 studies with a total of 698 participants undergoing thoracotomy. There are two studies awaiting classification. The studies demonstrated high heterogeneity in insertion and use of both regional techniques, reflecting real-world differences in the anaesthesia techniques. Overall, the included studies have a moderate to high potential for bias, lacking details of randomization, group allocation concealment or arrangements to blind participants or outcome assessors. There was low to very low-quality evidence that showed no significant difference in 30-day mortality (2 studies, 125 participants. risk ratio (RR) 1.28, 95% confidence interval (CI) 0.39 to 4.23, P value = 0.68) and major complications (cardiovascular: 2 studies, 114 participants. Hypotension RR 0.30, 95% CI 0.01 to 6.62, P value = 0.45; arrhythmias RR 0.36, 95% CI 0.04 to 3.29, P value = 0.36, myocardial infarction RR 3.19, 95% CI 0.13, 76.42, P value = 0.47); respiratory: 5 studies, 280 participants. RR 0.62, 95% CI 0.26 to 1.52, P value = 0.30). There was moderate-quality evidence that showed comparable analgesic efficacy across all time points both at rest and after coughing or physiotherapy (14 studies, 698 participants). There was moderate-quality evidence that showed PVB had a better minor complication profile than TEB including hypotension (8 studies, 445 participants. RR 0.16, 95% CI 0.07 to 0.38, P value < 0.0001), nausea and vomiting (6 studies, 345 participants. RR 0.48, 95% CI 0.30 to 0.75, P value = 0.001), pruritis (5 studies, 249 participants. RR 0.29, 95% CI 0.14 to 0.59, P value = 0.0005) and urinary retention (5 studies, 258 participants. RR 0.22, 95% CI 0.11 to 0.46, P value < 0.0001). There was insufficient data in chronic pain (six or 12 months). There was no difference found in and length of hospital stay (3 studies, 124 participants). We found no studies that reported costs. Paravertebral blockade reduced the risks of developing minor complications compared to thoracic epidural blockade. Paravertebral blockade was as effective as thoracic epidural blockade in controlling acute pain. There was a lack of evidence in other outcomes. There was no difference in 30-day mortality, major complications, or length of hospital stay. There was insufficient data on chronic pain and costs. Results from this review should be interpreted with caution due to the heterogeneity of the included studies and the lack of reliable evidence. Future studies in this area need well-conducted, adequately-powered RCTs that focus not only on acute pain but also on major complications, chronic pain, length of stay and costs.

Plain-language summary: We found 14 studies involving 698 participants. Whilst all 14 studies compared broadly the analgesic efficacy of PVB and TEB in participants undergoing open thoracotomy, there were significant differences in the timing, method of insertion and medications used in PVB and TEB. This makes direct comparison difficult. Patient follow-up was limited to the immediate post-surgery period (up to five days post-surgery) with only two studies reporting long-term outcomes such as chronic pain. There are two studies awaiting classification. We found no difference between PVB and TEB in terms of death at 30 days and major complications. PVB appeared to be as effective as TEB in pain control post-surgery. TEB was associated with minor complications such as low blood pressure, nausea and vomiting, itching and urinary retention when compared to PVB. We did not find any difference in length of hospital stay between PVB and TEB. There was insufficient information to assess chronic pain and health costs. We found low-quality evidence for death at 30 days, with limited information provided by only two studies reporting this outcome. We only found low to very low-quality evidence for major complications due to lack of information, with only one study reporting these outcomes. We found moderate-quality evidence for acute pain control in the immediate postoperative period. We found moderate-quality evidence for minor complications.