Impact of Sugammadex versus Neostigmine on Diaphragmatic Function and Respiratory Recovery in Morbidly Obese Patients with Moderate Neuromuscular Block: A Randomised Double-Blind Controlled Trial

Purpose: Compared with neostigmine, sugammadex promotes faster neuromuscular recovery, but its impact on diaphragmatic function and respiratory recovery in the morbidly obese cohort, and the mechanism underlying its reduction of postoperative pulmonary complications remain unclear. This study aims to compare the effects of sugammadex and neostigmine on diaphragmatic function and respiratory recovery in morbidly obese patients after surgery, and to investigate the role of diaphragmatic function in the reduction of sugammadex-associated postoperative pulmonary complications. Patients and Methods: For neuromuscular blockade reversal, 104 morbidly obese patients with moderate neuromuscular block (train-of-four count = 2, ratio < 0.9) were randomly assigned to receive either neostigmine (50 μg kg-1+atropine 20 μg kg-1, n=51) or sugammadex (2 mg kg-1, n=53). Measurements of diaphragmatic excursion (DE) and thickening fraction (TF) were taken during deep and quiet breathing at T0 (baseline), T1 (10 min), and T2 (30 min) after extubation. The primary outcome measure was the change in deep breathing diaphragmatic excursion (ΔDE DB ) from baseline at T2. The secondary outcome measures included ΔDE QB , ΔDE DB , and ΔTF at T1; ΔDE QB and ΔTF at T2; postoperative oxygenation index; number of respiratory reminders; and the frequency of postoperative pulmonary complications. Results: At T2, the ΔDE DB was smaller in the sugammadex group compared with the neostigmine group (0.05 cm vs. 0.28 cm; P < 0.001). At T1, the ΔDE QB , ΔDE DB , and ΔTF all differed significantly between groups, as did the ΔTF at T2 (all P ≤ 0.001). The sugammadex group also demonstrated a higher oxygenation index ( P =0.004) and a lower incidence of postoperative pulmonary complications ( P =0.007). Conclusion: In morbid obesity, sugammadex promotes faster diaphragmatic recovery and improves respiratory outcomes compared with neostigmine and is associated with a lower incidence of postoperative pulmonary complications. Keywords: diaphragm, obesity, morbid, sugammadex, postoperative pulmonary complications