title: The effect of lung inflation on absolute ventricular volume measurement by conductance.
abstract: BACKGROUND
  Conductance catheter in vivo ventricular volume measurements during lung ventilation may provide important information on left ventricular (LV) function. Breathing potentially may alter parallel conductance (V(c)), complicating interpretation of the conductance-derived volume signals. The effects of controlled positive pressure lung inflation (PPLI) on measured parallel conductance with dual-field conductance volumetry were investigated.
  
  
  METHODS
  Eight anaesthetized pigs were instrumented with an LV dual-field conductance volumetry catheter. V(c) was measured repeatedly, using the hypertonic saline injection method, at three different levels of lung insufflation: continuous positive airway pressure (PPLI) 0, 5, and 10 cm H(2)O.
  
  
  RESULTS
  V(c)s measured at PPLI 0, 5 and 10 cm H(2)O were 70.9 +/- 4.8, 70.7 +/- 5.5 and 70.5 +/- 5.9 ml, respectively. The corresponding uncalibrated end-diastolic volumes (EDV(u)) were 115.5 +/- 7.1, 117.0 +/- 7.5 and 117.5 +/- 7.7 ml, respectively. Mean coefficients of variance for V(c) and EDV(u) at all three PPLI levels were 3.8% and 1.25%, respectively.
  
  
  CONCLUSIONS
  Several levels of PPLI demonstrated no systematic change in parallel conductance for LV dual-field conductance volume signal. We concluded that lung inflation at these levels does not generate changes in V(c).
authors.affiliation: Surgical and Perioperative Sciences, Anesthesiology and Intensive Care Medicine, Umeå University Hospital, Sweden. michael.haney@anestesi.umu.se
authors.forename: Michael F
authors.initials: MF
authors.lastname: Haney
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Göran
authors.initials: G
authors.lastname: Johansson
authors.forename: Björn
authors.initials: B
authors.lastname: Biber
mesh_terms: D000818:Animals; D002306:Cardiac Volume; D002404:Catheterization; D007327:Insufflation; D008168:Lung / Q000502:physiology*; D011175:Positive-Pressure Respiration; D012462:Saline Solution, Hypertonic; D034421:Sus scrofa; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D012462:Saline Solution, Hypertonic