title: Esophageal versus surface recording of diaphragm compound muscle action potential.
abstract: BACKGROUND
  Repeated diaphragm compound muscle action potential (CMAP) recordings may help to understand the pathophysiology of respiratory muscle weakness. Neurally adjusted ventilator assist (NAVA) uses esophageal EMG electrodes to drive the ventilator. We evaluated the feasibility of CMAP recordings using these electrodes and established normal values.
  
  
  METHODS
  Bilateral cervical phrenic nerve electrical stimulation was performed in 15 healthy volunteers. CMAP recordings with esophageal NAVA electrodes were compared with surface electrode recordings during inspiratory and expiratory pause.
  
  
  RESULTS
  Compared with surface recordings, esophageal CMAP amplitudes were higher with increased latencies. Differences between the 2 techniques were most prominent in inspiration. For both recording techniques, amplitudes were higher, and latencies were longer during inspiration. Latencies were also longer when measured on the left side.
  
  
  CONCLUSIONS
  Diaphragm CMAPs can be measured using the commercially available esophageal NAVA probe. This may facilitate repeated diaphragm CMAP studies in mechanically ventilated patients.
authors.affiliation: Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Freiburgstrasse 10, 3010, Bern, Switzerland.
authors.forename: Karin A
authors.initials: KA
authors.lastname: Ackermann
authors.forename: Lukas
authors.initials: L
authors.lastname: Brander
authors.forename: Daniel
authors.initials: D
authors.lastname: Tuchscherer
authors.forename: Ralph
authors.initials: R
authors.lastname: Schröder
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Jakob
authors.forename: Jukka
authors.initials: J
authors.lastname: Takala
authors.forename: Werner J
authors.initials: WJ
authors.lastname: Z'graggen
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D003964:Diaphragm / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D004947:Esophagus / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010791:Phrenic Nerve / Q000502:physiology*; D055815:Young Adult
keywords: diaphragm; electroneurography; esophageal recordings; neurally adjusted ventilator assist; phrenic nerve