title: Functional assessment of the pharynx at rest and during swallowing in partially paralyzed humans: simultaneous videomanometry and mechanomyography of awake human volunteers.
abstract: BACKGROUND
  Functional characteristics of the pharynx and upper esophagus, including aspiration episodes, were investigated in 14 awake volunteers during various levels of partial neuromuscular block. Pharyngeal function was evaluated using videoradiography and computerized pharyngeal manometry during contrast bolus swallowing.
  
  
  METHODS
  Measurements of pharyngeal constrictor muscle function (contraction amplitude, duration, and slope), upper esophageal sphincter muscle resting tone, muscle coordination, bolus transit time, and aspiration under fluoroscopic control (laryngeal or tracheal penetration) were made before (control measurements) and during a vecuronium-induced partial neuromuscular paralysis, at fixed intervals of mechanical adductor pollicis muscle train-of-four (TOF) fade; that is, at TOF ratios of 0.60, 0.70, 0.80, and after recovery to a TOF ratio > 0.90.
  
  
  RESULTS
  Six volunteers aspirated (laryngeal penetration) at a TOF ratio < 0.90. None of them aspirated at a TOF ratio > 0.90 or during control recording. Pharyngeal constrictor muscle function was not affected at any level of paralysis. The upper esophageal sphincter resting tone was significantly reduced at TOF ratios of 0.60, 0.70, and 0.80 (P < 0.05). This was associated with reduced muscle coordination and shortened bolus transit time at a TOF ratio of 0.60.
  
  
  CONCLUSIONS
  Vecuronium-induced partial paralysis cause pharyngeal dysfunction and increased risk for aspiration at mechanical adductor pollicis TOF ratios < 0.90. Pharyngeal function is not normalized until an adductor pollicis TOF ratio of > 0.90 is reached. The upper esophageal sphincter muscle is more sensitive to vecuronium than is the pharyngeal constrictor muscle.
authors.affiliation: Department of Anesthesiology, Karolinska Hospital and Institute, Stockholm, Sweden.
authors.forename: L I
authors.initials: LI
authors.lastname: Eriksson
authors.forename: E
authors.initials: E
authors.lastname: Sundman
authors.forename: R
authors.initials: R
authors.lastname: Olsson
authors.forename: L
authors.initials: L
authors.lastname: Nilsson
authors.forename: H
authors.initials: H
authors.lastname: Witt
authors.forename: O
authors.initials: O
authors.lastname: Ekberg
authors.forename: R
authors.initials: R
authors.lastname: Kuylenstierna
mesh_terms: D000328:Adult; D003679:Deglutition / Q000502:physiology*; D004947:Esophagus / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D010614:Pharynx / Q000187:drug effects* / Q000502:physiology; D014673:Vecuronium Bromide / Q000494:pharmacology*
chemical_list: D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide