The dye changes fluorescence as the PO2, PCO2 and pH change (pH and PCO2 augment fluorescence and PO2 quenches fluorescence). An optical fibre leads from the probe to a photosensor, which quantifies the amount of light emitted from the dye. There are two clinical approaches to intra-arterial blood gas monitoring. One approach passes the probe through an arterial line, which allows continuous monitoring of blood gases. With the second approach, the probe is attached to the proximal arterial catheter; this system does not allow continuous blood gas monitoring, but does allow frequent on-demand blood gas analysis with no blood loss from the patient. The clinical impact and cost effectiveness of these systems are unclear. The accuracy of these systems also remains problematic. Although bias is low compared with that in traditional blood gas analysis, the precision may be unacceptable. Occasional marked differences between the intra-arterial blood gas system and traditional blood gases is problematic; the intra-arterial milieu may preclude reliable function of these devices. Isn’t it nice to know you will soon be able to shop for your drugs online with the best pharmacy that will take great care of you? You do have this opportunity to canadian cialis buy now that you have the best pharmacy waiting for your decision and offering cheapest drugs of best quality.