What should be done first when drawing a post-treatment BUN?

When drawing a post-treatment Blood Urea Nitrogen (BUN) level, the initial step is to turn off the ultrafiltration (UF) rate and the dialysate flow rate (DFR). This action is crucial because it ensures that the blood sample reflects the patient's condition accurately without any interference from ongoing treatment processes. By stopping the UF rate and DFR, you prevent any additional fluid or solute from affecting the concentration of substances in the blood, such as urea nitrogen, which is the focus of the post-treatment test.

Taking this step first allows for a steady state to be established in the bloodstream so that the sample drawn is representative of the patient's metabolic status post-dialysis. Once these rates are turned off, other actions like flushing the line, notifying the patient, or checking for free flow can follow, but they should come after ensuring that the treatment parameters that could compromise the accuracy of the BUN measurement are addressed.