title: Functional evaluation and practice survey to guide purchasing of intravenous cannulae.
abstract: BACKGROUND
  There are wide variations in the physical designs and attributes between different brands of intravenous cannulae that makes product selection and purchasing difficult. In a systematic assessment to guide purchasing, we assessed two cannulae - Cannula P and I. We proposed that the results of in-vitro performance testing of the cannulae would be associated with preference after clinical comparison.
  
  
  METHODS
  We designed an observer-blinded randomised head-to-head trial between the 18, 20 and 22 gauge versions of Cannula P and I. Our primary end-point was pressure (mmHg) generated during various flow rates and our secondary end-point was the force (Newton) required to slide the catheter away from the needle. This was followed by a prospective electronic survey following a two-week clinical trial period.
  
  
  RESULTS
  The mean difference in resistance between Cannula P and I was: 307 mmHg.L-1.hr-1 (95% CI: 289-325, p < 0.001) for 22G; 135 mmHg.L-1.hr-1 (95% CI: 125-144, p < 0.001) for 20G; and 27 mmHg.L-1.hr-1 (95% CI: 26-28, p < 0.001) for 18G. The mean difference in the force needed to displace the catheter away from its needle was: 1.41 N (95% CI: 1.09-1.73, p < 0.001) for 22G; 0.19 N (95% CI: -0.04-0.41, p = 0.12) for 20G; and 1.96 N (95% CI: 1.40-2.52, p < 0.001) for 18G. After a trial period, all 16 anaesthetist who had used both cannulae preferred Cannula I to P.
  
  
  CONCLUSIONS
  The evaluation process described here could help hospitals improve efficient product selection and purchasing decisions for intravenous cannulae.
authors.affiliation: Department of Anaesthesia, Royal Darwin Hospital, Tiwi, NT 0810, Australia. stanley.tay@nt.gov.au.
authors.forename: Stanley
authors.initials: S
authors.lastname: Tay
authors.forename: Brian
authors.initials: B
authors.lastname: Spain
authors.forename: Kirstie
authors.initials: K
authors.lastname: Morandell
authors.forename: Jesse
authors.initials: J
authors.lastname: Gilson
authors.forename: Laurence
authors.initials: L
authors.lastname: Weinberg
authors.forename: David
authors.initials: D
authors.lastname: Story