Affiliations: Hydraulics Laboratory, Institute Biomedical Technology, University of Gent, Sint-Pietersnieuwstraat 41, 9000 Gent, Belgium
Correspondence:
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Correspondence to: Dirk De Wachter, Hydraulics Laboratory, Institute Biomedical Technology, University of Gent, Sint-Pietersnieuwstraat 41, 9000 Gent, Belgium. Tel.: +32 9 264 3281; Fax: +32 9 264 3595; E-mail: [email protected].
Abstract: To study factors influencing the distribution of local anaesthetics in the subarachnoid space, an in vitro model is constructed which takes into account the natural curvature of the spinal column and the volume occupation of spinal cord and nerve fibres to resemble the in vivo situation. Three Marcaine® solutions of different baricity (1003, 1008, 1030 kg/m3) are injected with a 22 G, a 27 G Quincke point needle and a 18 G multiport catheter into three models of non-pathological spinal columns with injection flow speeds of 0.6, 0.2 or 0.1 ml/s. Methylene blue is added for visual and qualitative assessment of drug distribution. Baricity is the main actor in the spreading of the drug solution. For all other variables, no significant difference is found after ten minutes, though the initial distribution may differ according to the geometry used. A hypobaric solution yields a remarked difference between fast and slower injections. The position of the catheter should be controlled.
Keywords: Local anaesthetics, subarachnoid space, in vitro model, spinal column curvature, catheter injection, baricity
