title: Elevated BIS and Entropy values after sugammadex or neostigmine: an electroencephalographic or electromyographic phenomenon?
abstract: BACKGROUND
  Sugammadex is designed to antagonize neuromuscular blockade (NMB) induced by rocuronium or vecuronium. In clinical practice, we have noticed a rise in the numerical values of bispectral index (BIS) and Entropy, two electroencephalogram (EEG) - based depth of anesthesia monitors, during the reversal of the NMB with sugammadex. The aim of this prospective, randomized, double-blind study was to test this impression and to compare the effects of sugammadex and neostigmine on the BIS and Entropy values during the reversal of the NMB.
  
  
  METHODS
  Thirty patients undergoing gynecological operations were studied. Patients were anesthetized with target-controlled infusions of propofol and remifentanil, and rocuronium was used to induce NMB. After operation, during light propofol-remifentanil anesthesia, NMB was antagonized with sugammadex or neostigmine. During the following 5 min, the numerical values of BIS, BIS electromyographic (BIS EMG) and Entropy were recorded on a laptop computer, as well as the biosignal recorded by the Entropy strip. The Entropy biosignal was studied off-line both in time and frequency domain to see if NMB reversal causes changes in EEG.
  
  
  RESULTS
  In some patients, administration of sugammadex or neostigmine caused a significant rise in the numerical values of BIS, BIS EMG and Entropy. This phenomenon was most likely caused by increased electromyographic (EMG) activity. The administration of sugammadex or neostigmine appeared to have only minimal effect on EEG.
  
  
  CONCLUSIONS
  The EMG contamination of EEG causes BIS and Entropy values to rise during reversal of rocuronium-induced NMB in light propofol-remifentanil anesthesia.
authors.affiliation: Coxa Ltd, Hospital for Joint Replacement, Tampere, Finland. antti.j.aho@uta.fi
authors.forename: A J
authors.initials: AJ
authors.lastname: Aho
authors.forename: K
authors.initials: K
authors.lastname: Kamata
authors.forename: A
authors.initials: A
authors.lastname: Yli-Hankala
authors.forename: L-P
authors.initials: LP
authors.lastname: Lyytikäinen
authors.forename: A
authors.initials: A
authors.lastname: Kulkas
authors.forename: V
authors.initials: V
authors.lastname: Jäntti
mesh_terms: D000328:Adult; D001812:Blood-Brain Barrier; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects*; D004576:Electromyography; D019277:Entropy; D006801:Humans; D008875:Middle Aged; D009388:Neostigmine / Q000494:pharmacology*; D019148:Neuromuscular Blockade; D011446:Prospective Studies; D000077122:Sugammadex; D047408:gamma-Cyclodextrins / Q000494:pharmacology*
chemical_list: D047408:gamma-Cyclodextrins; D000077122:Sugammadex; D009388:Neostigmine