No Tourniquet Please!!!

Hello All,

I wanted to write about an important issue today. It was called to my attention recently that not every individual with Periodic Paralysis knows that using a tourniquet when having blood drawn can result in potassium levels which are higher than they really are. It is important to understand that improper use of a tourniquet and the clenching of the fist can result in false lab results for potassium levels. The pressure (too tight) and time (too long) of the tourniquet can raise the level of potassium as much as 10% to 20%. This difference can be important when making a decision about treatment or trying to get diagnosed. The following articles explain this problem.

"Pseudohyperkalemia is typically caused by hemolysis during
venipuncture (by either excessive vacuum of the blood draw or by a
collection needle that is of too fine a gauge); excessive tourniquet
time or fist clenching during phlebotomy (which presumably leads to
efflux of potassium from the muscle cells into the bloodstream);[4] or
by a delay in the processing of the blood specimen."
http://en.wikipedia.org/wiki/Hyperkalemia#Pseudohyperkalemia

"Pseudohyperkalemia Caused by Fist Clenching during Phlebotomy"
http://www.nejm.org/action/showImage?doi=10.1056/NEJM199005033221806&iid=f001
http://www.nejm.org/doi/full/10.1056/NEJM199005033221806
http://www.ncbi.nlm.nih.gov/pubmed/2325722
http://en.wikipedia.org/wiki/Hyperkalemia#Pseudohyperkalemia

"Excessive tourniquet time, too tight tourniquet or fist clenching
during phlebotomy (which presumably leads to efflux of potassium from
the muscle cells into the bloodstream) are other important cause of
fictitious hyperkalemia."

http://www.ijccm.org/article.asp?issn=0972-5229;year=2007;volume=11;issue=4;spage=215;epage=217;aulast=Sharma

But I guess we should ask first "When have you calibrated pressure
gauge of the tourniquet?" (unless the nurse tend to lose temper...)
http://www.tourniquets.org/use_care.php#calibrating_testing

It is imperative for one with Periodic Paralysis to know the above information whenever blood is drawn. Ask the technician or nurse to draw the blood without a tourniquet. Be sure to have this important information written and handy in case of an emergency or an ambulance must be called and you are unable to speak. I keep this information in a plastic folder along with everything I know is important and that the paramedics must know when coming to my aid in an emergency. I approach it as if I will have no one with me to explain my needs. I keep it near the door and take it with me when I leave home.

Until later…

More links:

http://www.questdiagnostics.com/dms/Documents/Physician-Newsletter/2011_fall.pdf
http://www.phlebotomy.com/pt-stat/stat0709.html