central line blood sampling - page 2

I am in the process of updating our P&P for PICC Insertion and Maintenance in the hospital. I have done extensive literature searches regarding blood sampling from central lines. What I have... Read More

  1. by   concerned lab person
    I am not an RN but I am a lab technician. I can tell you that nursing procedures have not kept up with laboratory technology. I just completed testing in my lab that shows as little as 90 microliters of heparin flush per 1mL of patient blood can skew the glucose, chloride, sodium, and especially the potassium in most general chemistries. The potassium was greatly affected. Before changing or making policies about blood sampling from a central line or any line please check with your labs manager or director to check the sensitivity level of their instruments. Never ever draw from the line that a substance is infusing that you want to test for. It does effect the test!!!! You should always throw away the amount of your flush you pushed and the dead space of the lumens. Clamp off all but the line you are pulling from. Stop anything transfusing for no less than 20 minutes before drawing for lab work. If you can't stop the line then don't use the central line for lab testing. Do a venipuncture.
  2. by   IVRUS
    Quote from concerned lab person
    I am not an RN but I am a lab technician. I can tell you that nursing procedures have not kept up with laboratory technology. I just completed testing in my lab that shows as little as 90 microliters of heparin flush per 1mL of patient blood can skew the glucose, chloride, sodium, and especially the potassium in most general chemistries. The potassium was greatly affected. Before changing or making policies about blood sampling from a central line or any line please check with your labs manager or director to check the sensitivity level of their instruments. Never ever draw from the line that a substance is infusing that you want to test for. It does effect the test!!!! You should always throw away the amount of your flush you pushed and the dead space of the lumens. Clamp off all but the line you are pulling from. Stop anything transfusing for no less than 20 minutes before drawing for lab work. If you can't stop the line then don't use the central line for lab testing. Do a venipuncture.
    Dear Lab tech... I appreciate your desire to educate, but I can emphatically tell you that research shows that there is NO reason to turn off medications/solutions for more than one minute.. You may not be aware of anatomy of the central vasculature, but you have a blood flow dumping out of the subclavian into the SVC of over 2000 mls a minute. That is plently of time to rid the body of the contents of a solution/medication.
    As far as the heparin flush creating problems, well, I've seen research where it definetely interfers with coag sampling, but not any studies that show it causes problems with electrolytes. Can you publish where you got your information from?

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