Muscle relaxants are integral part of modern anesthesia. They optimize intubating conditions, reduce laryngeal trauma and improve operating conditions. Drawback is a possible pharmacological (muscle relaxing) effect of these drugs beyond the end of the operation (i.e. post-operative residual curarization: PORC). Reportedly about 30% of all patients who received muscle relaxants show signs of PORC when arriving in the post-anesthesia care unit. PORC comprises the risk of impaired post-operative fine motor and coordinative skills with a possible impairment of swallowing pharyngeal secretions with an increased risk of aspiration after extubation. Possible deleterious effects of this could be pneumonia, bronchitis, myocardial infarction, cardiac insufficiency, stroke or re-operation.