Dialyzer clearance

to calculate the dialyzer clearance for any substance ,please follow these stips:
1. adjust the blood flow at certain speed; 200, 300 or 400 ml per min.
2. keep the machine running for minimum 5 minutes with out any alarm.
3. take two sampels at the same time from the injection ports dierctly pre and post dialyzer.
4. compute the lab results