title: Testing rocuronium-induced neuromuscular blockade at the stapedius muscle using stapedius reflex measurements.
abstract: BACKGROUND
  Neuromuscular monitoring prior to emergence from anaesthesia has been shown to be necessary to achieve adequate airway protection in order to decrease postoperative pulmonary complications. In the present study we hypothesized that stapedius reflex measurement allows the detection of residual neuromuscular blockade using the stapedius muscle following the administration of rocuronium.
  
  
  METHODS
  Parallel stapedius and acceleromyographic measurements were performed on 20 patients undergoing cholecystectomy. Acceleromyographic measurements were continuously performed during the course of anaesthesia, whereas the stapedius reflex was measured on different occasions: (1) after premedication but before anaesthesia induction, (2) after induction, but before administration of muscle relaxant, (3) after administration of muscle relaxant, (4) during the course of surgical anaesthesia at regular intervals, and (5) continuously performed during emergence from anaesthesia, until the stapedius reflex threshold returned to normal.
  
  
  RESULTS
  The intensity of the sound energy at which the stapedius reflex is detectable was similar: 89.5 ± 9.9 dB(mean ± SD) after premedication and after anaesthetic induction. However, after administration of rocuronium, when the twitch height decreased to 5%, the stapedius reflex disappeared, indicating a total block of the stapedius muscle.During the recovery phase (twitch>10%) significantly higher sound energies compared to baseline values were necessary to evoke the reflex, indicating residual inhibition of the stapedius muscle. At the point where stapedius reflex threshold returned to normal the twitch height averaged about 50% showing low sensitivity of the tympanometry in detecting residual neuromuscular blockade.
  
  
  CONCLUSIONS
  The neuromuscular effect of rocuronium on the stapedius muscle can be detected using stapedius reflex measurements. Due to its methodological limitation and low sensitivity, the method cannot be recommended for the monitoring of residual neuromuscular blockade.
authors.affiliation: Department of Anaesthesiology and Intensive Care, University of Debrecen, Debrecen, Hungary.
authors.forename: P
authors.initials: P
authors.lastname: Sárkány
authors.forename: E
authors.initials: E
authors.lastname: Tassonyi
authors.forename: R
authors.initials: R
authors.lastname: Nemes
authors.forename: A
authors.initials: A
authors.lastname: Timkó
authors.forename: A
authors.initials: A
authors.lastname: Pongrácz
authors.forename: Béla
authors.initials: B
authors.lastname: Fülesdi
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods / Q000592:standards; D000328:Adult; D000732:Androstanols / Q000008:administration & dosage*; D002763:Cholecystectomy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods* / Q000592:standards*; D009407:Nerve Block / Q000379:methods* / Q000592:standards*; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage; D011183:Postoperative Complications / Q000175:diagnosis / Q000517:prevention & control; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D000077123:Rocuronium; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds / Q000187:drug effects; D013198:Stapedius / Q000502:physiology; D014732:Vibration
chemical_list: D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D000077123:Rocuronium