title: Infusion-line pressure as a real-time monitor of convection-enhanced delivery in pre-clinical models.
abstract: BACKGROUND
  Acute convection-enhanced delivery (CED) is a neurosurgical delivery technique that allows for precise and uniform distribution of an infusate to a brain structure. It remains experimental due to difficulties in ensuring successful delivery. Real-time monitoring is able to provide immediate feedback on cannula placement, infusate distribution, and if the infusion is proceeding as planned or is failing due to reflux or catheter obstruction.
  
  
  METHODS
  Pressure gradient is the driving force behind CED, with the infusion pressure being directly proportional to the flow-rate. The aim of this study was to assess the feasibility of using infusion-line pressure profiling to distinguish in real-time between succeeding and failing CED infusions. To do so we delivered cresyl violet dye at 0.5, 1.0 and 2.0 μl/min via CED in vitro using 0.6% agarose gel and in vivo to the rat striatum.
  
  
  RESULTS
  Infusions that failed in agarose gel models could only be differentiated late during the procedures. In the rat in vivo model, the infusion-line profiles of obstructed infusions were not distinctive from those of successful infusions.
  
  
  CONCLUSIONS
  Intraoperative magnetic resonance imaging (MRI) is used for real-time visualisation of cannula placement and infusate distribution. Particularly for animal pre-clinical work, it would be advantageous to supplement MRI with a cheap, accessible technique to monitor infusions and provide a real-time measure of infusion success or failure.
  
  
  CONCLUSIONS
  Infusion-line pressure monitoring was of limited value in identifying successful CED with small volume infusions, whilst its utility for large volume infusion remains unknown.
authors.affiliation: Neurosurgical Service of Western Australia, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, 6009 Perth, Australia; School of Surgery, The University of Western Australia, 35 Stirling Highway, Crawley, 6009 Perth, Australia. Electronic address: markmfl@gmail.com.
authors.forename: Miu Fei
authors.initials: MF
authors.lastname: Lam
authors.forename: Stacy W L
authors.initials: SW
authors.lastname: Foo
authors.forename: Meghan G
authors.initials: MG
authors.lastname: Thomas
authors.forename: Christopher R P
authors.initials: CR
authors.lastname: Lind
mesh_terms: D000818:Animals; D048588:Benzoxazines / Q000008:administration & dosage*; D061807:Catheter Obstruction; D057785:Catheters; D004396:Coloring Agents / Q000008:administration & dosage*; D018481:Convection; D004195:Disease Models, Animal; D016503:Drug Delivery Systems / Q000379:methods*; D005260:Female; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D010300:Parkinson Disease; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D048588:Benzoxazines; D004396:Coloring Agents; C028911:cresyl violet
keywords: Convection enhanced delivery; Infusion-line pressure monitoring; Parkinson's disease; Pre-clinical model