Intravenous patient-controlled analgesia (iv-PCA) is the gold standard for the treatment of moderate to severe postoperative pain. It is used in more than 20% of cases after major surgery. Well known disadvantages of this method include the need of intravenous line (invasive, infection risk), the risk of pump programming error, possible delay for ambulation/barrier for enhanced rehabilitation programmes, and time/resource demanding (the need of preparation and installation). Sublingual sufentanil based PCA (Zalviso®) addresses cited issues. The safety and analgesia efficiency of this system is well described. However, the usability and satisfaction of Zalviso® varies depending on clinical settings. The goal of this study is to evaluate the usability and satisfaction of patients, nurses, and physical therapists using Zalviso® System during the first 72 hours in the settings of Enhanced Recovery After Surgery protocol after major interventions associated with moderate to severe postoperative pain.