title: Frequency requirements for zeroing transducers in hemodynamic monitoring.
abstract: BACKGROUND
  Accurate hemodynamic monitoring information can be obtained only if the transducer/amplifier system is used correctly. One major component of correct use is zeroing the transducer to provide a relative reference point on which to measure hemodynamic pressures. However, nursing requirements for frequency of zeroing are inconsistent. In addition, the concepts of leveling and zeroing are frequently confused.
  
  
  OBJECTIVE
  To determine whether transducers drift from zero (+/- 2 mm Hg), and if they do not drift from zero, how long they hold a zero value.
  
  
  METHODS
  The study, conducted in four midwestern hospitals, was carried out in two parts: an initial 10-day bench test of 50 transducers and an evaluation of 388 transducers attached to patients for 1 to 5 days. Transducers were monitored over time after being consistently leveled.
  
  
  RESULTS
  Bench testing indicated that 100% of transducers did not drift +/- 2 mm Hg from zero during the study period. In the clinical study, only 1.3% of transducers drifted from zero. Five transducers drifted +/- 2 mm Hg from zero, with a range of -5 to 3 mm Hg.
  
  
  CONCLUSIONS
  We conclude that transducers used for hemodynamic monitoring require zeroing only on initial setup and disconnection from the amplifier.
authors.affiliation: Barnes Hospital, St. Louis, Mo., USA.
authors.forename: T
authors.initials: T
authors.lastname: Ahrens
authors.forename: J C
authors.initials: JC
authors.lastname: Penick
authors.forename: M K
authors.initials: MK
authors.lastname: Tucker
mesh_terms: D002138:Calibration; D004209:Disposable Equipment; D006439:Hemodynamics; D006801:Humans; D015146:Midwestern United States; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000451:nursing; D013997:Time Factors; D014159:Transducers / Q000592:standards*