title: The dependency of expiratory airway collapse on pump system and flow rate in liquid ventilated rabbits.
abstract: OBJECTIVE
  To evaluate the influence of pump system and flow pattern on expiratory airway collapse (EAC) in total perfluorocarbon ventilation. -
  
  
  METHODS
  Prospective, controlled, randomized animal trial for determination of (1) post-mortem changes by repeated expiration procedures (EP) with a constant flow piston pump (PP) before and after sacrifice (n = 8 rabbits), (2) differences between pump systems by subjecting animals to both PP and roller pump (RP) circuits for expiration (n = 16 rabbits). EP were performed using a servo-controlled shut-off at airway pressures < 25 cm H subset 2O randomly with either pump at different flows. -
  
  
  RESULTS
  Expired volumes before and after sacrifice were not significantly different. PP and RP revealed identical mean flows, while significantly more liquid was drained using PP (p<0.05). Increasing differences towards higher flow rates indicated profound flow pulsatility in RP. -
  
  
  CONCLUSIONS
  (1) post-mortem changes in expired volumes are not significant, (2) EAC is related to flow rate and pump system; (3) relationship between expiratory flow rate and drainable liquid volume is linear inverse; (4) PP provides higher drainage than RP. -
  
  
  CONCLUSIONS
  Expiratory airway collapse is related to flow rate and pump system, post mortem changes in expirable volumes are not significant. Relationship between expiratory flow rate and drainable liquid volume is linear inverse, piston pump expiration provides higher drainage volumes than roller pump expiration.
authors.affiliation: Universitätsklinikum Mannheim, Fakultät für Klinische Medizin der Universität Heidelberg, Mannheim, Germany. juergen.meinhardt@anaes.ma.uni-heidelberg.de
authors.forename: J P
authors.initials: JP
authors.lastname: Meinhardt
authors.forename: B A
authors.initials: BA
authors.lastname: Ashton
authors.forename: G M
authors.initials: GM
authors.lastname: Annich
authors.forename: M
authors.initials: M
authors.lastname: Quintel
authors.forename: R B
authors.initials: RB
authors.lastname: Hirschl
mesh_terms: D000818:Animals; D004867:Equipment Design; D005260:Female; D005466:Fluorocarbons; D006842:Hydrocarbons, Brominated; D008168:Lung / Q000503:physiopathology; D008176:Lung Volume Measurements; D008297:Male; D011175:Positive-Pressure Respiration / Q000295:instrumentation; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D011817:Rabbits; D013813:Therapy, Computer-Assisted / Q000295:instrumentation; D012122:Ventilators, Mechanical
chemical_list: D005466:Fluorocarbons; D006842:Hydrocarbons, Brominated; C003072:perflubron