title: In vitro evaluation of intragastric PCO2 measurement by air tonometry.
abstract: OBJECTIVE
  To assess the in vitro performance of a new device, the Tonocap, for semi-continuous air tonometry of regional PCO2 in the gastrointestinal tract.
  
  
  METHODS
  The tonometer consists of an air filled balloon-tipped catheter, connected to a prototype Tonocap system. The tonometer was placed in saline baths at steady-state PCO2's ranging from 0 to 105 torr, to evaluate bias, precision and reproducibility to PCO2 measurements. The response time was defined as the time needed to detect 95% of an instantaneous change in bath PCO2.
  
  
  RESULTS
  The bias of the PCO2 measurement (mean +/- SD) was -2 +/- 2% and reproducibility (coefficient of variation) was 2 +/- 1%. The response time was 19 +/- 2 min.
  
  
  CONCLUSIONS
  Tonocap air tonometry is simple and eliminates most sources of error associated with conventional saline tonometry. The bias, precision, reproducibility and response time in vitro are consistent with a clinically reliable device.
authors.affiliation: Department of Gastroenterology, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: J J
authors.initials: JJ
authors.lastname: Kolkman
authors.forename: L J
authors.initials: LJ
authors.lastname: Zwaarekant
authors.forename: K
authors.initials: K
authors.lastname: Boshuizen
authors.forename: A B
authors.initials: AB
authors.lastname: Groeneveld
authors.forename: S G
authors.initials: SG
authors.lastname: Meuwissen
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis*; D005069:Evaluation Studies as Topic; D008365:Manometry / Q000379:methods*; D008961:Models, Structural; D010313:Partial Pressure; D015203:Reproducibility of Results; D013270:Stomach / Q000098:blood supply / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide