title: Avoid cruising on the uroflowmeter: evaluation of cruising artifact on spinning disc flowmeters in an experimental setup.
abstract: OBJECTIVE
  The aim of our study was to access the variability of maximum flow rate (Q(max)), average flow rate (Q(av)) and flow pattern while varying the point of impact of flow on the flowmeter.
  
  
  METHODS
  Water was delivered through a motorised tube holder in a standardised experimental set up. Flow was directed in 4 different directions on the funnel; 1) Periphery, 2) Base, 3) Centre and, 4) in a cruising motion from the periphery of the funnel to the centre and back again. The variation in the Q(max), Q(av) and the flow pattern were studied at 4 different flow rates. The variables recorded when the flow was directed at the centre of the funnel was taken as baseline.
  
  
  RESULTS
  There was a significant difference in the Q(max) and Q(av)when the point of impact was at the periphery or in a cruising motion compared to the centre. The difference was more marked with cruising motion with a characteristic flow pattern. The maximum percentage difference in Q(av) was 4.1%, whereas the difference in Q(max) was higher at 16.6% on comparing crusing motion with the values from the centre.
  
  
  CONCLUSIONS
  We have demonstrated a significant variation in Q(max), Q(av) and flow pattern with change in the point of impact on the flowmeter. Though the changes in Q(av) were statistically significant, the alteration in the recorded Q(max) values was more striking. Our study emphasizes the importance of combining Q(av) and flow pattern along with Q(max) in interpretation of results of uroflowmetry.
authors.affiliation: Royal Blackburn Hospital, East Lancashire Hospitals NHS Trust, Blackburn, United Kingdom. saddla@yahoo.co.uk
authors.forename: Sanjai Kumar
authors.initials: SK
authors.lastname: Addla
authors.forename: Rajender Reddy
authors.initials: RR
authors.lastname: Marri
authors.forename: Sai Lakshmi
authors.initials: SL
authors.lastname: Daayana
authors.forename: Paul
authors.initials: P
authors.lastname: Irwin
mesh_terms: D016477:Artifacts; D002138:Calibration; D004867:Equipment Design; D045268:Flowmeters / Q000592:standards; D008422:Materials Testing; D015203:Reproducibility of Results; D012212:Rheology / Q000295:instrumentation* / Q000592:standards; D014563:Urodynamics