Document Detail


Focal delivery during direct infusion to brain: role of flow rate, catheter diameter, and tissue mechanics.
MedLine Citation:
PMID:  10516265     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Direct interstitial infusion is a technique capable of delivering agents over both small and large dimensions of brain tissue. However, at a sufficiently high volumetric inflow rate, backflow along the catheter shaft may occur and compromise delivery. A scaling relationship for the finite backflow distance along this catheter in pure gray matter (x(m)) has been determined from a mathematical model based on Stokes flow, Darcy flow in porous media, and elastic deformation of the brain tissue: x(m) = constant Q(o)(3)R(4)r(c)(4)G(-3)mu(-1) 1/5 [corrected] = volumetric inflow rate, R = tissue hydraulic resistance, r(c) = catheter radius, G = shear modulus, and mu = viscosity). This implies that backflow is minimized by the use of small diameter catheters and that a fixed (minimal) backflow distance may be maintained by offsetting an increase in flow rate with a similar decrease in catheter radius. Generally, backflow is avoided in rat gray matter with a 32-gauge catheter operating below 0.5 microliter/min. An extension of the scaling relationship to include brain size in the resistance term leads to the finding that absolute backflow distance obtained with a given catheter and inflow rate is weakly affected by the depth of catheter tip placement and, thus, brain size. Finally, an extension of the model to describe catheter passage through a white matter layer before terminating in the gray has been shown to account for observed percentages of albumin in the corpus callosum after a 4-microliter infusion of the compound to rat striatum over a range of volumetric inflow rates.
Authors:
P F Morrison; M Y Chen; R S Chadwick; R R Lonser; E H Oldfield
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of physiology     Volume:  277     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1999 Oct 
Date Detail:
Created Date:  1999-11-17     Completed Date:  1999-11-17     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R1218-29     Citation Subset:  IM    
Affiliation:
Bioengineering and Physical Science Program, Office of Research Services, National Institutes of Health, Bethesda, Maryland 20892, USA. pmorris@box-p.nih.gov
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MeSH Terms
Descriptor/Qualifier:
Animals
Autoradiography
Brain* / physiology
Catheterization
Caudate Nucleus / metabolism
Drug Delivery Systems* / instrumentation
Models, Neurological*
Rats
Serum Albumin / administration & dosage,  pharmacokinetics
Chemical
Reg. No./Substance:
0/Serum Albumin
Comments/Corrections
Erratum In:
Am J Physiol 2002 Jun;282(6):section R following table of contents

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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