title: Assessing respiratory function depends on mechanical characteristics of balloon catheters.
abstract: BACKGROUND
  Respiratory muscle function and lung and chest wall mechanics are reliably assessed by esophageal and gastric balloon catheters. The aim of this in vitro bench study was to assess the mechanical properties of commercially available balloon catheters using an experimental model with 3 defined compliances (27, 54, 90 mL/cm H2O).
  
  
  METHODS
  Six catheters were investigated in 4 conditions: (1) balloon pressure during initial inflation, (2) static pressure measurements at different filling volumes, (3) estimation of set compliances in the experimental lung model at different levels of superimposed pressure, and (4) elastic balloon properties after 16 h of inflation.
  
  
  RESULTS
  5/6 catheters showed initial pressure artifacts resulting from material adhesion. All static pressure measurements could be performed with an error < 1 cm H2O. Balloon overfilling resulted in larger errors in 4/6 catheters. Compliance determined from pressure measurements via the catheters differed by < 5% from that determined from direct pressure measurements. Sixteen hours of inflation resulted in a broader working range, that is, overfilling effects occurred at higher filling volumes.
  
  
  CONCLUSIONS
  The reliability of pressure measurements and estimation of the lung model's compliance in the tested catheters are high. Filling volume appears to be critical for precise pressure measurement and compliance estimation. At first use, adhesion of the balloon material might prevent reliable pressure measurement.
authors.affiliation: Department of Pneumology, University Hospital of Freiburg, Freiburg, Germany. stephan.walterspacher@klinikum-konstanz.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Walterspacher
authors.affiliation: Department of Anesthesiology, Division for Experimental Anesthesiology, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: Lilli
authors.initials: L
authors.lastname: Isaak
authors.affiliation: Department of Anesthesiology, Division for Experimental Anesthesiology, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Guttmann
authors.affiliation: Department of Pneumology, University Hospital of Freiburg, Freiburg, Germany.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Kabitz
authors.affiliation: Department of Anesthesiology, Division for Experimental Anesthesiology, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schumann
mesh_terms: D016477:Artifacts; D057785:Catheters; D004548:Elasticity; D004947:Esophagus / Q000502:physiology; D006801:Humans; D008365:Manometry / Q000295:instrumentation*; D008422:Materials Testing; D055595:Mechanical Phenomena; D011312:Pressure; D012129:Respiratory Function Tests / Q000295:instrumentation*; D015656:Respiratory Mechanics / Q000502:physiology; D012132:Respiratory Muscles / Q000502:physiology; D013270:Stomach / Q000502:physiology
keywords: artificial respiration; esophagus; lung compliance; pulmonary mechanics; work of breathing