On Line Mesurement of Urea by Aplication in Paired Filtration Dialysis (PFD) Experience in Military Hospital Center

The present paper shows the design and development the on-line measure of urea in blood during paired filtration dialysis (PFD), using non-invasive technical by employ the optical sensing in the visible range. We design and used a simple prototype for measurement the Nitrogen Ureic in Blood (BUN) by employ the optical sensor. In addition we compared the Urea measured in blood Pre and Post treatment, as well beta2 Microglobulin, Paratahormone (PTHi), Tiroglobulin and Phosphorus, register by laboratory. Previous results obtained in Military Hospital Centre in Mexico displayed good correlation between BUN contents and optical absorbance in the red region obtained through the arterial line in hemodialysis machine. Our hypothesis considers that the cause of this dependence is the volume change of the red cells with the urea concentration due to the osmotic pressure and to the mechanisms regulation cell. The reduction of the volume cells to a decrease respect to optical absorbance measurement. The most relevant parameter is water extraction along the dialysis treatment, given that changes in the blood fluid and arterial pressure (Hypotention or Hypertention), thus affecting the measurement principle.