The principle of Microdialysis

Microdialysis is a minimally invasive technique to explore and monitor the chemistry in blood and living tissues.

Continuous tissue monitoring is enabled through the insertion of small Microdialysis probes. A physiological salt solution is slowly constantly pumped through a semipermeable membrane and the solution is equilibrated with the surrounding tissue fluid.   

The Microdialysis Catheter mimics a blood capillary. Substances from the extracellular fluid of the tissue diffuse across the membrane of the catheter into the perfusion fluid inside the catheter. 

 

 

 

 

The main design resembles a concentric tube where the perfusion fluid enters through an inner tube; flows to its distal end; exits the tube and enters the space between the inner tube and the outer dialysis membrane. This is where the “dialysis” takes place, i.e. the diffusion of molecules between the extra cellular fluid and the perfusion fluid. 

Microdialysis offers the opportunity to sample tissue chemistry with high accuracy and without taking any blood. The dialysate is extracted into small vials for bedside or laboratory analysis.