BackgroundWe aimed to evaluate the effects of modified thoracoabdominal nerve block through perichondrial approach (M-TAPA) block on respiratory dysfunction after laparoscopic sleeve gastrectomy (LSG) in patients with obesity.MethodsIn this prospective randomized-controlled study, 60 patients aged 18-65 years and ASA PS II-III were included. Patients were divided into two groups: group M-TAPA (n = 30) and group control (n = 30). The primary outcome was the results of spirometric respiratory function tests. The secondary outcomes were total opioid consumption, postoperative resting, dynamic pain scores, and assessing the functional recovery via quality of recovery (QoR)-15 on postoperative day 1.ResultsThe FVC, FEV1, PEF, and predicted FEV1 values were significantly different between the groups, whereas the results were similar for FEV1/FVC values in the postoperative first hour. The decreases in FVC, FEV1, PEF, and predicted FEV1 values were higher in the group control. Total tramadol consumption at 0-24 h was significantly higher in the group control than in the group M-TAPA (group M-TAPA = 170 (0-300), group control = 220 (80-300); p = 0.013). Resting and dynamic NRS pain scores at the 1st, 2nd, 6th, and 12th postoperative hours were significantly higher in the control group than in the M-TAPA group.ConclusionsThe M-TAPA block in patients with obesity undergoing LSG reduced postoperative respiratory dysfunction and opioid consumption.