title: Relative impact of respiratory muscle activity on tidal flow and end expiratory volume in healthy neonates.
abstract: BACKGROUND
  It has been suggested that infants dynamically regulate their tidal flow and end-expiratory volume level. The interaction between muscle activity, flow and lung volume in spontaneously sleeping neonates is poorly studied, since it requires the assessment of transcutaneous electromyography of respiratory muscles (rEMG) in matched comparison to lung function measurements.
  
  
  METHODS
  After determining feasibility and repeatability of rEMG in 20 spontaneously sleeping healthy neonates, we measured the relative impact of intercostal and diaphragmatic EMG activity in direct comparison to the resulting tidal flow and FRC.
  
  
  RESULTS
  We found good feasibility, repeatability and correlation of timing indices between rEMG activity and flow. The rEMG amplitude was significantly dependent on the resistive load of the face mask. Diaphragm and intercostal muscle activity commenced prior to the onset of flow and remained active during the expiratory cycle. The relative contribution of intercostal and diaphragmatic activity to flow was variable and changed dynamically.
  
  
  CONCLUSIONS
  Using matched rEMG, air flow and lung volume measurements, we have found good feasibility and repeatability of intercostal and diaphragm rEMG measurements and provide the first quantitative measures of the temporal relationship between muscle activity and flow in spontaneously sleeping healthy neonates. Lung mechanical function is dynamically regulated and adapts on a breath to breath basis. So, non-invasive rEMG measurements alone or in combination with lung function might provide a more comprehensive picture of pulmonary mechanics in future studies. The data describing the timing of EMG and flow may be important for future studies of EMG triggered mechanical ventilation.
authors.affiliation: Division of Paediatric Respiratory Medicine, Department of Pediatrics, University of Bern, Bern, Switzerland.
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Hutten
authors.forename: Leo A
authors.initials: LA
authors.lastname: van Eykern
authors.forename: Philipp
authors.initials: P
authors.lastname: Latzin
authors.forename: Manuela
authors.initials: M
authors.lastname: Kyburz
authors.forename: Wim M
authors.initials: WM
authors.lastname: van Aalderen
authors.forename: Urs
authors.initials: U
authors.lastname: Frey
mesh_terms: D004576:Electromyography; D005240:Feasibility Studies; D005652:Functional Residual Capacity / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D012016:Reference Values; D012132:Respiratory Muscles / Q000502:physiology*; D013990:Tidal Volume / Q000502:physiology*