title: Sonographic assessment of changes in diaphragmatic kinetics induced by inspiratory resistive loading.
abstract: OBJECTIVE
  Diaphragmatic breathing patterns under resistive loading remain poorly documented. To our knowledge, this is the first study assessing diaphragmatic motion under conditions of inspiratory resistive loading with the use of sonography.
  
  
  METHODS
  We assessed diaphragmatic motion during inspiratory resistive loading in 40 healthy volunteers using M-mode sonography. In phase I of the study, sonography was performed during normal quiet breathing without respiratory loading. In phase II, sonography was performed after application of a nose clip and connection of the subjects to a pneumotachograph through a mouth piece. In phase III, the participants were assessed while subjected to inspiratory resistive loading of 50 cm H(2)O/L/s.
  
  
  RESULTS
  Compared with baseline, the application of a mouth piece and nose clip induced a significant increase in diaphragmatic excursion (from 1.7 to 2.3 cm, P < 0.001) and a decrease in respiratory rate (from 13.4 to 12.2, P < 0.01). Inspiratory resistive loading induced a further decrease in respiratory rate (from 12.2 to 8.0, P < 0.01) and a decrease in diaphragmatic velocity contraction (from 1.2 to 0.8 cm/s, P < 0.01), and also an increase in tidal volume (from 795 to 904 mL, P < 0.01); diaphragmatic excursion, however, did not change significantly.
  
  
  CONCLUSIONS
  Inspiratory resistive loading induced significant changes in diaphragmatic contraction pattern, which mainly consisted of decreased velocity of diaphragmatic displacement with no change in diaphragmatic excursion. Tidal volume, increased significantly; the increase in tidal volume, along with the unchanged diaphragmatic excursion, provides sonographic evidence of increased recruitment of extradiaphragmatic muscles under inspiratory resistive loading.
authors.affiliation: ICU Department, Papageorgiou Hospital, Thessaloniki, Greece. elenisoil@hotmail.com
authors.forename: Eleni
authors.initials: E
authors.lastname: Soilemezi
authors.forename: Matthew
authors.initials: M
authors.lastname: Tsagourias
authors.forename: Michael A
authors.initials: MA
authors.lastname: Talias
authors.forename: Elpidoforos S
authors.initials: ES
authors.lastname: Soteriades
authors.forename: Vasilios
authors.initials: V
authors.lastname: Makrakis
authors.forename: Epaminondas
authors.initials: E
authors.lastname: Zakynthinos
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Matamis
mesh_terms: D000328:Adult; D000403:Airway Resistance / Q000502:physiology*; D003964:Diaphragm / Q000000981:diagnostic imaging* / Q000502:physiology*; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D012016:Reference Values; D014463:Ultrasonography