BACKGROUND: The sustained administration of deep neuromuscular blockade (NMB) improves surgical conditions compared to moderate NMB and might be effective in the laparoscopic Roux-en-Y gastric bypass (LRYGB). This study aimed to evaluate the effect of sustained intravenous deep NMB on improving surgical conditions and pain intensity following LRYGB. METHODS: This randomized, double-blind clinical trial was conducted in São Luís, Maranhão, Brazil, between October 2021 and December 2023. Patients undergoing LRYGB were randomly assigned to moderate (reversed with 2 mg/kg of sugammadex) or deep NMB (reversed with 4 mg/kg of sugammadex). RESULTS: Seventy-one patients were evaluated in the study, divided into moderate NMB with 37 patients and deep NMB group with 34 patients. There was no difference between the groups regarding gender, age, weight, height, and comorbidities. Also, in the duration of anesthesia (moderate, 2 h 26 min
deep, 2 h 27 min
p = 0.876), duration of surgery (moderate, 1 h 39 min
deep NMB: 1 h 40 min
p = 0.931), time to extubation (moderate, 5 min
deep, 7 min
p = 0.252), time to the first morphine request (moderate, 30 min
deep, 25 min on average
p = 0.776), mean morphine consumption in 24 h (moderate, 14 mg
deep, 10 mg
p = 0.133), and sevoflurane consumption (moderate, 50 mL
deep 50 mL
p = 0.884). There was no significant difference between the groups in pain scores at none of the evaluated moments. The Leiden-Surgical Rating Scale revealed a significant difference between the groups at 20/30 min (p = 0.015) and 60/70 min (p = 0.027), respectively. CONCLUSION: This study demonstrated improved surgical field visibility with deep compared to moderate NMB, without significant differences in other evaluated variables.