Effects of Serratus Anterior Plane Block on Early Recovery from Thoracoscopic Lung Resection: A Randomized, Blinded, Placebo-Controlled Trial

Background: The efficacy of serratus anterior plane block (SAPB) for treatment of pain after minimally invasive thoracic surgery remains unclear. This trial assesses the impact of SAPB on postoperative opioid consumption and on measures of early recovery after thoracoscopic lung resection. Methods: Patients undergoing minimally invasive anatomic lung resection at a single center were randomized to undergo SAPB with 40 mL of injectate containing bupivacaine 0.25%, clonidine 100 mcg, and dexamethasone 4 mg (SAPB group) or sham block with 40 mL of normal saline (placebo group) at the conclusion of surgery. The primary outcome was cumulative intravenous morphine equivalents during the first 24 h postoperatively. Secondary outcomes were intravenous morphine equivalents, pain scores at rest and with cough, inspiratory volume on incentive spirometry, and incidence of nausea/vomiting during the first 48 h postoperatively; Quality of Recovery–15 score on postoperative day 7; and length of stay. Results: Using the protocol-specified intention-to-treat analysis, the median (interquartile range, IQR) intravenous morphine equivalents was 10.6 (5.0 to 27.1) mg in SAPB patients (n=46) versus 18.8 (9.9 to 29.6) mg in placebo patients (n=46) (32% reduction; ratio=0.68 [95% CI, 0.44 to 1.06]; P =0.085). Of the secondary outcomes, only the composite pain with cough scores differed significantly in the SAPB group by a coefficient of -0.41 (95% CI, -0.81 to -0.01; P =0.044). A sensitivity as-treated analysis reported median (IQR) intravenous morphine equivalents of 10.0 (5.0 to 27.2) mg in SAPB patients (n=44) versus 19.9 (10.4 to 29.0) mg in placebo patients (n=48) (36% reduction; ratio=0.64 [95% CI, 0.41 to 1.00]; P =0.048). Conclusions: The protocol-specified intention-to-treat analysis demonstrated that SAPB did not result in a significant reduction in opioid consumption when added to a multimodal analgesic regimen after thoracoscopic anatomic lung resection. The sensitivity as-treated analysis showed a significant and modest clinical reduction in the primary outcome that warrants further investigation.