Following the gastrectomy, the reduction in pulmonary function is partly attributed to postoperative pain. Subcostal quadratus lumborum block (QLB) has recently emerged as a promising component in multimodal analgesia. We aimed to assess the impact of intermittent boluses of subcostal QLB on pulmonary function recovery and analgesic efficacy after gastrectomy.

Sixty patients scheduled for gastrectomy were randomly assigned to either control group (multimodal analgesia) or intervention group (intermittent boluses of subcostal QLB plus multimodal analgesia). Two primary outcomes included the preservation of forced expiratory volume in the first second (FEV1) and the pain scores (0-10 cm visual analog score) on coughing 24 h postoperatively. We assessed the pulmonary function parameters, pain score, morphine consumption and number of rescue analgesia at a 24-h interval up to 72 h (Day1, Day2, Day3 respectively) as secondary outcomes.

59 patients were analyzed in a modified intention-to-treat set. The preservation of FEV1 (median difference: 4.0%, 97.5% CI: −5.7 to 14.9, P = 0.332) and pain scores on coughing (mean difference: 0.0 cm, 97.5% CI: −1.1 to 1.2, P = 0.924) did not differ significantly between two groups. In the intervention group, the recovery of forced vital capacity (FVC) was faster 72 h after surgery (interaction effect of group*(Day3-Day0): estimated effect (β) =0.30 L, standard error (SE) =0.13, P = 0.025), pain scores at rest were lower in the first 3 days (interaction effect of group*(Day1-Day0): β = − 0.8 cm, SE = 0.4, P = 0.035; interaction effect of group*(Day2-Day0): β = − 1.0 cm, SE = 0.4, P = 0.014; and interaction effect of group*(Day3-Day0): β = − 1.0 cm, SE = 0.4, P values = 0.009 respectively), intravenous morphine consumption was lower during 0–24 h (median difference: −3 mg, 95% CI −6 to −1, P = 0.014) and in total 72 h (median difference: −5 mg, 95% CI −10 to −1, P = 0.019), and the numbers of rescue analgesia was fewer during 24-48 h (median difference: 0, 95% CI 0 to 0, P = 0.043). Other outcomes didn't show statistical differences.

Postoperative intermittent boluses of subcostal QLB did not confer advantages in terms of the preservation of FEV1 or pain scores on coughing 24 h after gastrectomy. However, notable effects were observed in analgesia at rest and FVC recovery.