title: The accuracy of the flowrate in flush-devices of disposable pressure transducers.
abstract: BACKGROUND
  Arterial and venous pressure is commonly measured using fluid filled catheters. To avoid obstruction they are continuously spilled by a flush-device. The accuracy of the flowrate has not been investigated previously.
  
  
  METHODS
  The accuracy of 5 different flush-devices available in Switzerland was checked for flowrate when factory new, after a single sterilization with ethylen-oxide, in a long-term test over 96 hours, after repeated handling of the integrated bypass and under application of a pulsing counter-pressure.
  
  
  RESULTS
  Flow is linearly related to differential-pressure and is constant over time. The flow of each flush-device at 200 mmHg differential-pressure was below the indicated 3 ml per hour (1.69 - 2.49 ml/h). Sterilization in two types produced a significant but not relevant difference in flowrate. Longtime-use, bypass actuation and pulsing pressure did not alter the flowrate significantly (p <0.05). In two factory-new flush-devices and 4 re-used ones a plugged capillary induced cessation of flow.
  
  
  CONCLUSIONS
  Flowrate in flush-devices is accurate under sterilization, longtime use, bypass-actuation and pulsing counter pressure. A plugged capillary occurred in a few new and reused flush-devices, which can be the explanation for clotted catheters in clinical use.
authors.affiliation: Institute of Anaesthesiology and Intensive Care, University Hospital, Bern, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Michel
authors.forename: F
authors.initials: F
authors.lastname: Roth
authors.forename: P
authors.initials: P
authors.lastname: Feigenwinter
authors.forename: A M
authors.initials: AM
authors.lastname: Zbinden
mesh_terms: D001795:Blood Pressure Determination / Q000295:instrumentation* / Q000706:statistics & numerical data; D004209:Disposable Equipment / Q000706:statistics & numerical data; D004868:Equipment Failure; D005069:Evaluation Studies as Topic; D006801:Humans; D015203:Reproducibility of Results; D013242:Sterilization / Q000379:methods; D014160:Transducers, Pressure / Q000706:statistics & numerical data