Lately, we have had some erroneous lab results when drawing blood samples from a CVC (single lumen) with TPN running. It is our policy to stop the TPN infusion for 2 minutes , flush with 10mls of saline, draw a 5ml blood discard, then draw the sample.  Is this an appropriate procedure for drawing blood from a single lumen CVC with TPN running? Usually, with a multilumen catheter, we use the line that does not have TPN running through it. Thank You in advance for help with this question. VickieÂ
A single lumen catheter infusing any fluid or medication should never be used for drawing a blood sample. As you have identified you will have inaccurate lab values. TPN infusing through a lumen would never allow accurate results regardless of how much you flushed or the discard volume.
Lynn Hadaway, M.Ed., RN, BC, CRNI
www.hadawayassociates.com
Lynn Hadaway, M.Ed., RN, NPD-BC, CRNI
Lynn Hadaway Associates, Inc.
PO Box 10
Milner, GA 30257
Website http://www.hadawayassociates.com
Office Phone 770-358-7861