Fresenius Medical Care DIASAFE 2008 K, Руководство оператора

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Chapter 4—Monitoring the Treatment
104 2008K Hemodialysis Machine Operator’s Manual Rev P
Kt/V & Access Flow Monitoring
How Kt/V is Derived
Online Clearance (OLC)—used in estimating the effectiveness of the dialysis treatment—can
be viewed in the “Kt/V AF” screen. The effectiveness of the treatment is based on the
amount of urea that is removed from the patient’s blood. It has been shown that sodium can
be used as a surrogate to urea for determining removal rates (clearance). The key to
determining the amount of urea cleared is based on the fact that urea clearance is almost
identical to sodium clearance.
To measure the effectiveness of treatment, the concentration of sodium in the dialysate is
adjusted for a brief duration. This changes the conductivity of the dialysate. The
conductivity of the dialysate is then measured before and after it passes through the dialyzer.
As the dialysate passes through the dialyzer, some of the sodium diffuses through the
membrane resulting in a different, post-dialyzer, conductivity reading. The amount of
sodium clearance (Kecn) can be calculated based on the change in conductivity of the
dialysate after it passed through the dialyzer.
Figure 47 – The Kt/V and Access Flow Screen
The following table describes the features found in the “Kt/V AF” screen on machines with
active OLC functionality.