title: Comparison of phonomyography with balloon pressure mechanomyography to measure contractile force at the corrugator supercilii muscle.
abstract: OBJECTIVE
  Phonomyography is based on the creation of low frequency sounds during muscle contraction, which can be recorded and used for neuromuscular monitoring. In this study, balloon pressure mechanomyography, a novel method to measure the force of contraction via pressure changes in an air-filled balloon, was compared with phonomyography to determine neuromuscular blockade at the corrugator supercilii muscle.
  
  
  METHODS
  After approval of the Ethics Committee and informed consent, 15 patients were studied. A small condenser microphone was taped to the area just above the eyebrow for phonomyography; an air-filled balloon was taped to the area just above the opposite eyebrow. After induction of anesthesia using remifentanil and propofol, a laryngeal mask airway was inserted without the aid of neuromuscular blocking agents. The facial nerve was stimulated supramaximally with single-twitch stimulation (0.1 Hz) using superficial electrodes placed on both temporal areas for onset and train-of-four stimulation every 12 sec during offset of neuromuscular blockade produced by mivacurium 0.1 mg.kg(-1). Onset and recovery measured by the two methods were compared using the t test and agreement between phonomyography and balloon pressure mechanomyography was examined using the Bland-Altman method.
  
  
  RESULTS
  Onset, peak effect, and time to reach 25%, 75%, and 90% of control twitch response for phonomyography vs balloon pressure method were 83 +/- 16 sec vs 81 +/- 15 sec, 80 +/- 15% vs 82 +/- 17%, 7.7 +/- 2.3 min vs 7.5 +/- 2.4 min, 9.9 +/- 4.1 min vs 10.5 +/- 4 min, and 12.6 +/- 4.3 min vs 13.1 +/- 4.5 min respectively without being significantly different. Mean bias was 1% with limits of agreement of -9 and +9% of twitch height (T1).
  
  
  CONCLUSIONS
  We applied a balloon pressure method to measure the force at the corrugator supercilii. Phonomyography at the corrugator supercilii shows good agreement with this modified version of mechanomyography.
authors.affiliation: Neuromuscular Research Group, Department of Anesthesiology, Centre hospitalier de l'université de Montréal, Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada. thomashemmerling@hotmail.com
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Hemmerling
authors.forename: Guillaume
authors.initials: G
authors.lastname: Michaud
authors.forename: Denis
authors.initials: D
authors.lastname: Babin
authors.forename: Guillaume
authors.initials: G
authors.lastname: Trager
authors.forename: François
authors.initials: F
authors.lastname: Donati
mesh_terms: D000328:Adult; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D004558:Electric Stimulation / Q000379:methods; D005152:Facial Muscles / Q000187:drug effects / Q000502:physiology*; D005154:Facial Nerve / Q000502:physiology; D005260:Female; D006801:Humans; D007546:Isoquinolines / Q000008:administration & dosage; D017214:Laryngeal Masks; D008297:Male; D000077590:Mivacurium; D016343:Monitoring, Intraoperative / Q000379:methods*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009213:Myography / Q000379:methods; D019148:Neuromuscular Blockade / Q000379:methods; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage; D010880:Piperidines / Q000008:administration & dosage; D011312:Pressure; D015742:Propofol / Q000008:administration & dosage; D000077208:Remifentanil; D013016:Sound; D013997:Time Factors
chemical_list: D018686:Anesthetics, Intravenous; D007546:Isoquinolines; D003473:Neuromuscular Nondepolarizing Agents; D010880:Piperidines; D000077590:Mivacurium; D000077208:Remifentanil; D015742:Propofol