title: Breath-to-breath analysis of abdominal and rib cage motion in surfactant-depleted piglets during high-frequency oscillatory ventilation.
abstract: OBJECTIVE
  To assess the value of monitoring abdominal and rib cage tidal displacement as an indicator of optimal mean airway pressure (Paw) during high-frequency oscillatory ventilation (HFOV).
  
  
  METHODS
  Prospective observational study in a university research laboratory.
  
  
  METHODS
  Eight piglets weighing 12.0+/-0.5 kg, surfactant depleted by lung lavage.
  
  
  METHODS
  Compliance of the respiratory system (C(rs)) was calculated from a quasistatic pressure volume loop. After initiation of HFOV lung volume was recruited by increasing Paw to 40 cmH(2)O. Then mean Paw was decreased in steps until PaO(2)/FIO(2) was below 100 mmHg. Proximal pressure amplitude remained constant.
  
  
  RESULTS
  Abdominal and rib cage tidal displacement was determined using respiratory inductive plethysmography. During HFOV there was maximum in tidal volume (Vt) in seven of eight piglets. At maximal mean Paw abdominal and rib cage displacement were in phase. Phase difference between abdominal and rib cage displacement increased to a maximum of 178+/-28 degrees at minimum mean Paw. A minimum in abdominal displacement and a maximum of Vt was found near the optimal mean Paw, defined as the lowest mean Paw where shunt fraction is below 0.1.
  
  
  CONCLUSIONS
  During HFOV abdominal and rib cage displacement displayed mean Paw dependent asynchrony. Maximal Vt and minimal abdominal displacement coincided with optimal C(rs), oxygenation, and ventilation, suggesting potential clinical relevance of monitoring Vt and abdominal displacement during HFOV.
authors.affiliation: Pediatric ICU, Department of Pediatrics, Vrije Universiteit Medical Centre, Amsterdam, The Netherlands. dg.markhorst@vumc.nl
authors.forename: Dick G
authors.initials: DG
authors.lastname: Markhorst
authors.forename: Jos R C
authors.initials: JR
authors.lastname: Jansen
authors.forename: Adrianus J
authors.initials: AJ
authors.lastname: van Vught
authors.forename: Huibert R
authors.initials: HR
authors.lastname: van Genderingen
mesh_terms: D000005:Abdomen / Q000502:physiology; D000818:Animals; D004195:Disease Models, Animal; D006612:High-Frequency Ventilation / Q000379:methods*; D008991:Monitoring, Physiologic; D010991:Plethysmography / Q000379:methods*; D035422:Pleural Cavity / Q000502:physiology; D011663:Pulmonary Surfactants / Q000378:metabolism*; D015656:Respiratory Mechanics / Q000502:physiology*; D012272:Ribs / Q000502:physiology; D034421:Sus scrofa; D013990:Tidal Volume
chemical_list: D011663:Pulmonary Surfactants