Acute pain after serratus anterior plane or thoracic paravertebral blocks for video-assisted thoracoscopic surgery: A noninferiority randomised trial.

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.