title: A simple, standard method to characterize pressure/flow performance of vascular access cannulas.
abstract: Vascular access cannulas for extracorporeal life support are characterized by French (Fr) size alone, which affords limited information on pressure (P) and flow (Q) performance, making their selection difficult. Previously, we developed an accurate metric of cannula performance, the M number, but its complexity and the need of a nomogram hindered its utility. We propose adoption of an easier and clinically useful metric to assess cannula performance: Q at 100 mm Hg P, the updated M number, or the "UM number." A circuit was created using a centrifugal pump, Tygon tubing, and a reservoir. A total of 74 cannulas (arterial, venous, and double lumen) ranging from 6 to 50 Fr size were studied. Glycerol solution with a viscosity of 3 cP was used to mimic blood. A Biopac system and ultrasonic flow probe was used to collect P/Q data across a cannula's performance range. The UM number describes the pressure-flow characteristics of any given cannula. It can be used to select access cannulas based on performance and to determine if flow matches expected flow during use.
authors.affiliation: Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Paulsen
authors.forename: Ryan
authors.initials: R
authors.lastname: Orizondo
authors.forename: Duy
authors.initials: D
authors.lastname: Le
authors.forename: Alvaro
authors.initials: A
authors.lastname: Rojas-Pena
authors.forename: Robert H
authors.initials: RH
authors.lastname: Bartlett
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002648:Child; D004867:Equipment Design; D005112:Extracorporeal Circulation / Q000295:instrumentation*; D018056:Hemorheology; D006801:Humans; D062666:Vascular Access Devices / Q000592:standards*