Single-injection thoracic paravertebral block for postoperative pain treatment after thoracoscopic surgery

Background. Thoracoscopic surgery can be associated with considerable postoperative pain. While the benefits of paravertebral block on pain after thoracotomy have been demonstrated, no investigations on the effects of paravertebral block on pain after thoracoscopy have been conducted. We tested the hypothesis that a single-injection thoracic paravertebral block, performed preoperatively, reduces pain scores after thoracoscopic surgery. Methods. Of 45 patients recruited, 40 completed the study. They were randomly allocated to two groups: the paravertebral group received i.v. patient-controlled analgesia (PCA) with morphine plus single-injection thoracic paravertebral block with bupivacaine 0.375% and adrenaline 1:200 000 0.4 ml kg(-1) (n=20). The control group was treated with a back puncture without injection and morphine PCA (n=20). Results. The main outcomes recorded during 48 h after surgery were pain scores using the visual analogue scale (VAS, 0-100). Secondary outcomes were cumulative morphine consumption and peak expiratory flow rate (PEFR). Half an hour and 24 h after surgery, median (25th-75th percentiles) VAS on coughing in the paravertebral group was 31.0 (20.0-55.0) and 30.5 (17.5-40.0) respectively and in the control group it was 70.0 (30.0-100.0) and 50.0 (25.0-75.0) respectively. The difference between the groups over the whole observation period was statistically significant (P < 0.05). Twenty-four and 48 h after surgery, median (25th-75th percentiles) cumulative morphine consumption (mg) was 49.0 (38.3-87.0) and 69.3 (38.8-118.5) respectively in the paravertebral group and 51.2 (36.0-84.1) and 78.1 (38.4-93.1) in the control group (statistically not significant). No differences were found in PEFR or the incidence of any side-effects between groups. Conclusion. We conclude that single-shot preoperative paravertebral block improves post-operative pain treatment after thoracoscopic surgery in a clinically significant fashion.