title: Catheter locking-solution spillage: theory and experimental verification.
abstract: A theory was developed allowing the prediction of the spillage volume after injection of locking solution into a catheter. This theory was corroborated by in-vitro measurements using colorized fluid injected automatically by a micropump into a stirred container with clear fluid. The amount of spilled solution was measured with a fiberoptic spectrometer equipped with a dip probe. Straight cylindrical tubing was used as catheter.
  
  
  RESULTS
  The theory predicts the beginning of spillage when 50% of the catheter filling volume is injected. When the nominal filling volume is injected, 25% of the solution is spilled and the mean concentration at the catheter tip is 50% of the locking solution concentration.
  
  
  METHODS
  Spillage was slightly less than predicted (20-25% at nominal filling volume). During the experiments it was recognized that a small air bubble trapped in the Luer connection during connection reduces the spillage volume to 10-15%.
authors.affiliation: hdp@aon.at
authors.forename: Hans-Dietrich
authors.initials: HD
authors.lastname: Polaschegg
mesh_terms: D002408:Catheters, Indwelling; D005119:Extravasation of Diagnostic and Therapeutic Materials; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects; D008962:Models, Theoretical; D012212:Rheology; D012996:Solutions
chemical_list: D012996:Solutions; D006493:Heparin