Patent ID: 8524154

Claim:
A metabolite monitoring system comprising: (a) a microdialysis probe including a semi-permeable membrane and a probe flow path passing from an inlet through a sensing volume adjacent to said semi-permeable membrane to an outlet; (b) a fluid delivery device for delivering dialysate to said inlet; and (c) a metabolite monitoring system associated with said outlet for monitoring a concentration of at least one metabolite in said dialysate from said microdialysis probe, wherein said microdialysis probe has an operative volume, and wherein said fluid delivery device is configured to deliver a pulsed flow of said dialysate to said inlet such that each pulse of said dialysate delivered to said inlet has a volume less than said operative volume of said microdialysis probe, wherein said fluid delivery device includes: (a) a dialysate delivery arrangement for generating said pulsed flow of dialysate; and (b) a reagent delivery arrangement for supplying a reagent for mixing with the dialysate from said microdialysis probe, wherein said reagent delivery arrangement and said dialysate delivery arrangement each includes a fluid reservoir acted upon by a piston to deliver the fluid, wherein said reagent delivery arrangement and said dialysate delivery arrangement are mechanically linked so as to maintain a fixed ratio between a quantity of dialysate delivered and a quantity of reagent delivered, and wherein said fluid reservoirs of said reagent delivery arrangement and said dialysate delivery arrangement are substantially concentric fluid reservoirs, said substantially concentric fluid reservoirs being at least partially enclosed between opposing overlapping piston elements such that relative axial displacement of said overlapping piston elements generates delivery of said dialysate and said reagent in said fixed ratio.