Postoperative Residual Curarisation at Arrival in the Post-anesthesia Care Unit

• Background \& Rationale: Several studies have documented that neuromuscular block often persists in the PACU, even with the administration of acetylcholinesterase inhibitors. Postoperative residual curarisation ranges between 4 and 50% depending on the diagnostic criteria, the type of non-depolarizing neuromuscular blocking drug (NMBD), the administration of a reversal agent, and the use of neuromuscular monitoring. Residual paralysis is associated with postoperative complications such as hypoxia, weakness, and respiratory failure. However, these complications may have many other causes so that the role of neuromuscular block is often unrecognized. Thus, it is important to manage neuromuscular block and have a strategy to prevent, diagnose, and treat residual paralysis, with neuromuscular monitoring and reversal of neuromuscular block in routine anesthetic practice. The data in the current literature on residual paralysis in the PACU were almost exclusively obtained with acetylcholinesterase inhibitors as they were the only reversal agents available prior to the introduction in clinical practice of sugammadex (Bridion®) in the European Union and in some other countries, except for the USA. Reassessment of practice in this regard is relevant, now that sugammadex (Bridion®) has become available in our country since 2009.

Five years ago a similar exploratory, non-interventional, non-randomized study took place in Belgium. This previous study will help to assess the two different periods (2005-2011) in terms of management of neuromuscular block in the operating room of a large regional community hospital.

• Study Design: This is an observational/non-interventional, non-randomized study involving adult patients undergoing different types of elective surgical procedures requiring general anesthesia with NMBDs. This study will reflect real life clinical practice. The anesthetic technique in terms of drugs and type of monitoring used will be the entire responsibility of the anesthesiologist.

All study activities will be consistent with EU directive 2001/20/EC for non-interventional studies (also known as observational/non-interventional studies).

Administration of NMBDs and reversal agents (as well as all drugs which will be used during anesthesia) will be performed in accordance with routine anesthetic practice; will follow good clinical practice and labeling of drugs. No other interventional means, methods or procedures are scheduled than those for routine care of the patient. Furthermore, there will be no additional visits to the hospital or a mandatory visit schedule, deviating from normal clinical practice.

• Study Flowchart: On arrival to the PACU, 3 l/min oxygen will be applied to all subjects by a nasal cannula. Baseline oxygen saturation values are recorded 1 min after application of the oxygen. Immediately after the patients' arrival in the PACU, a study nurse will record their tympanic temperatures and the acceleromyographic responses of their adductor pollicis muscle as percent of the train-of-four (TOF%) on stimulation of the ulnar nerve (TOF-Watch®, Organon Ireland Ltd., a division of MSD, Swords, Co., Dublin, Ireland). The stimulus current will be set in the range 25-35 mA for tolerance purpose without compromising the results. Two consecutive TOF measurements (separated by 15 s) will be obtained, and the average of the 2 values will be recorded. If measurements differ by >10%, additional TOF measurements will be obtained (up to 4 TOF values), and the closest 2 ratios averaged. A TOF of 90% will be used as cut-off value to exclude residual paralysis. Pulse oximetry will be measured continuously throughout the PACU admission, and SpO2 values will be recorded at 1-min intervals for the first 30 min. PACU nurses caring for the patient will document the occurrence of any of the following events during the first 30 min of PACU admission: the number of episodes of hypoxemia (SpO2<90%), the lowest SpO2 observed by nursing staff, the requirement for either tactile or verbal stimulation to maintain SpO2 greater than 90%, and any clinical evidence of airway obstruction. Patient demographic data, type of surgical procedure, duration of anesthesia, as well as data collected relating to neuromuscular management, will be recorded and stored on a PC.