BACKGROUND Serratus anterior plane blocks (SAPBs) and thoracic paravertebral blocks (TPVBs) can both be used for video-assisted thoracic surgery. However, it remains unknown whether the analgesic efficacy of a SAPB is comparable to that of a TPVB. OBJECTIVE We tested the primary hypothesis that SAPBs provide noninferior analgesia compared with TPVBs for video-assisted thoracic surgery. DESIGN A noninferiority randomised trial. SETTING Shanghai Chest Hospital, between August 2018 and November 2018. PATIENTS Ninety patients scheduled for video-assisted thoracic lobectomy or segmentectomy were randomised. Patients were excluded if they were unable to perform the visual analogue pain scale, or surgery was converted to thoracotomy. INTERVENTIONS Blocks were performed after induction of general anaesthesia. The three groups were paravertebral blocks (n = 30); serratus anterior plane blocks (n = 29); and general anaesthesia alone (n = 30). PRIMARY OUTCOME MEASURES Visual analogue pain scores (0 to 10 cm) at rest and while coughing, and Prince-Henry pain scores (0 to 4 points) were used to assess postoperative analgesia at 2, 24 and 48 h after surgery. We assessed the noninferiority of SAPBs with TPVBs on all three primary pain outcomes using a delta of 1 cm or one point as appropriate. RESULTS The mean difference (95% confidence intervals) in visual analogue scores between the SAPBs and TPVBs was −0.04 (−0.10 to 0.03) cm at rest, −0.22 (−0.43 to −0.01) cm during coughing and −0.10 (−0.25 to 0.05) for Prince-Henry pain scores. As the upper limit of the confidence intervals were less than 1 (all P < 0.001), noninferiority was claimed for all three primary outcomes. Compared with general anaesthesia alone, the VAS scores at rest and while coughing, and the Prince-Henry pain scores for the two blocks were significantly lower during the initial 2 h after surgery. CONCLUSIONS Serratus anterior plane blocks are quicker and easier to perform than paravertebral blocks and provide comparable analgesia in patients having video-assisted thoracic surgery. Both blocks provided analgesia that was superior to general anaesthesia alone during the initial 2 h after surgery. TRIAL REGISTRATION Chinese Clinical Trial Registry, identifier: ChiCTR1800017671.

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