Dose Finding Study for Sugammadex and Neostigmine at Residual Neuromuscular Blockade (T4/T1 = 0.5)

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.

In order to avoid PORC patients with residual neuromuscular block receive a muscle relaxant antagonist from the anesthetist at the end of the operation. However, these drugs (neostigmine, pyridostigmine, etc.) from the class of cholinesterase inhibitors have unwanted effects such as bradycardia, increased gastro-intestinal motility, post-operative nausea and vomiting, salivation etc. To decrease these unwanted side effects cholinesterase inhibitors have to be given in combination with parasympatholyics e.g. atropine or glycopyrrolate with their own spectrum of unwanted side effects.

From October 2008 on, Sugammadex, a completely new reversal drug was introduced in to clinical practice. Sugammadex, is a modified gamma-cyclodextrine able to specifically bind rocuronium (a steroidal muscle relaxant). The complex is eliminated via the kidneys. However, all studies so far have focussed on reversal of profound or deep neuromuscular blockade. This study is designed to compare recovery times after reversal of a residual neuromuscular block (TOF-ratio 0.5) with different doses of either the neostigmine or sugammadex.