The primary objective of this study is to evaluate the incidence of postoperative residual curarization, as defined by a train-of-four <90%, upon postanaesthesia care unit arrival. Anesthetists tend to use train-of-four monitoring in the operating theatre to interpret muscle tone. Train-of-four monitoring is a widely used term for the peripheral nerve stimulation used in neuromuscular blockade monitoring. Hypothesizing a change in our practice since 2006-2012 (Cammu G, Anesth Analg 2006; 102: 426-9 and Cammu G, Anaesth Intensive Care 2012; 40: 999-1006), residual neuromuscular block as well as the use of intraoperative neuromuscular transmission monitoring and reversal of neuromuscular blocking agents will again be prospectively evaluated in 2018. The present study aims to compare these three periods (2006-2012-2018) in terms of management of neuromuscular block in the operating room and to look for a relationship with the incidence of postoperative residual curarization.

Inclusion Criteria:

• 18 years of age or older;
• Informed consent signed;
• Admission for elective surgery;
• Administration of non-depolarizing neuromuscular blocking agents during surgery;
• Tracheal intubation

Exclusion Criteria:

• Evidence of renal, hepatic, metabolic, and/or neuromuscular disorders
• Ejection fraction <20%
• Admission for emergency surgery; or cardiothoracic surgery
• Reoperation during the same hospital admission

About 600 surgical patients (the first 600 inpatients and outpatients scheduled for anesthesia during the study period who meet the study criteria).