Chris H Martini,1 GH Maarten Honing,1 Lori D Bash,2 Erik Olofsen,1 Marieke Niesters,1 Monique van Velzen,1 Albert Dahan,1 Martijn Boon1 1Department of Anesthesiology, Leiden University Medical Center, Leiden, the Netherlands; 2Center for Observational and Real- World Evidence (CORE), Merck & Co., Inc, Kenilworth, NJ, USACorrespondence: Chris H Martini, Department of Anesthesiology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333, ZA, the Netherlands, Tel +31 71 526 2301, Email c.h.martini@lumc.nlIntroduction: Muscle relaxants are often given during general anesthesia to facilitate endotracheal intubation. However lingering effects after anesthesia-end may lead to respiratory compromise in the PACU. Strategies to reduce these adverse events include monitoring neuromuscular block, the use of short-acting agents and active pharmacological reversal before extubation. At Leiden University Medical Center (LUMC), a tertiary care academic hospital in the Netherlands, various muscle relaxants and reversal agents are freely available to all clinicians without restrictions. In this setting, we intended to evaluate how patient and surgical characteristics impacted the use of these agents for a variety of non-cardiac surgeries.Material and Methods: This is a retrospective database study of adult patients that had received elective, non-cardiac surgery and general anesthesia with endotracheal intubation between 2016 and 2020 at LUMC in the Netherlands. Exclusion criteria consisted of patients pharmacologically reversed with both sugammadex and neostigmine during the same procedure, diagnosed with myasthenia gravis, receiving pyridostigmine therapy, or with renal failure (eGFR < 30 mL.min.1.73m2).Results: We retrieved 23,373 patient records of which 9742 were excluded because one or more exclusion criteria were met. The final cohort consisted of 13,631 cases. Rocuronium was the most commonly used muscle relaxant (88.5%); sugammadex was the most commonly used reversal agent (99.9% of those ...