Patent ID: 8333107
Filing Date: 2012-12-18
Classification: A61B

Abstract:
1. A method for accurately determining the permeability of a wall of a microdialysis probe, comprising: a) providing a probe comprising a section of relatively highly permeable membrane relative to any materials to which the membrane is attached for support and positioned between an inlet to a source of dialysate and an outlet to a receptacle, and through which membrane a diffusible agent is to be transferred; b) putting said probe in contact with a medium into which an agent is to be transferred by diffusion, the volume of the medium being large enough that the concentration of the agent in the medium is always negligible compared to its concentration in the dialysate; c) perfusing a known quantity of a dialysate containing said agent in a known concentration (C d) allowing said known quantity of dialysate to remain stationary for a resting time (t e) flushing out said known quantity of dialysate with a single pulse of a known volume (V f) determining by assay the concentration of said agent in said dialysate in said receptacle and from that determining the mass (M) using Equation 68; g) repeating steps (c) through (f) with the same flow rate and sample volume, and at least one different resting time t h) plotting the mass from steps (f) and (g) to determine how said mass changes with t i) taking the slope (dM/dt) of the plot of step (h); j) using said slope to calculate probe wall permeability (P).