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, BC, CRNI
Lynn Hadaway Associates, Inc.
126 Main Street, PO Box 10
Milner, GA 30257
Website http://www.hadawayassociates.com
Office Phone 770-358-7861