title: [Pressure control in medical gas distribution systems].
abstract: OBJECTIVE
  To assess whether the pressure gauges at the downstream part of pressure regulators are accurate enough to ensure that pressure in O2 pipeline is always higher than in Air pipeline and that pressure in the latter is higher than pressure in N2O pipeline. A pressure difference of at least 0.4 bar between two medical gas supply systems is recommended to avoid the reflow of either N2O or Air into the O2 pipeline, through a faulty mixer or proportioning device.
  
  
  METHODS
  Prospective technical comparative study.
  
  
  METHODS
  Readings of 32 Bourdon gauges were compared with data obtained with a calibrated reference transducer. Two sets of measurements were performed at a one month interval.
  
  
  RESULTS
  Pressure differences between Bourdon gauges and reference transducer were 8% (0.28 bar) in average for a theoretical maximal error less than 2.5%. During the first set of measurements, Air pressure was higher than O2 pressure in one place and N2O pressure higher than Air pressure in another. After an increase in the O2 pipeline pressure and careful setting of pressure regulators, this problem was not observed at the second set of measurements.
  
  
  CONCLUSIONS
  Actual accuracy of Bourdon gauges was not convenient enough to ensure that O2 pressure was always above Air pressure. Regular controls of these pressure gauges are therefore essential. Replacement of the faulty Bourdon gauges by more accurate transducers should be considered. As an alternative, the increase in pressure difference between O2 and Air pipelines to at least 0.6 bar is recommended.
authors.affiliation: Service d'anesthésie, institut Gustave-Roussy, France.
authors.forename: J L
authors.initials: JL
authors.lastname: Bourgain
authors.forename: L
authors.initials: L
authors.lastname: Benayoun
authors.forename: P
authors.initials: P
authors.lastname: Baguenard
authors.forename: G
authors.initials: G
authors.lastname: Haré
authors.forename: J M
authors.initials: JM
authors.lastname: Puizillout
authors.forename: V
authors.initials: V
authors.lastname: Billard
mesh_terms: D000388:Air; D000769:Anesthesia, Inhalation / Q000295:instrumentation*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D002138:Calibration; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control; D008365:Manometry / Q000295:instrumentation*; D009609:Nitrous Oxide / Q000008:administration & dosage*; D010100:Oxygen / Q000008:administration & dosage*; D011312:Pressure; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results
chemical_list: D018685:Anesthetics, Inhalation; D009609:Nitrous Oxide; D010100:Oxygen