Investigating Discrepant Potassium Results
Physicians at a group practice with one main testing laboratory and five satellite drawing locations are losing confidence in the potassium results the laboratory is releasing, claiming they are sporadic, and also falsely elevated. Over a six-month period, the laboratory's manager tracked potassium reports and found several occurrences of questionable results involving up to three percent of its patients. She ruled out the testing methodology and instrumentation as potential sources of error.
The laboratory manager shifts her focus from troubleshooting isolated occurrences to an investigation of preanalytical processes system-wide. Her goal is to identify the cause(s) of the problem and implement appropriate corrective action. Her challenges are two-fold: 1) minimize the potential for negative patient outcomes due to inaccurate potassium results and the liability it brings to the facility, and 2) protect the laboratory against a loss of credibility among clinicians. Examining and ruling out the numerous preanalytical activities that can wreak havoc on potassium results requires a methodical approach.
Location-specific errors. She begins by identifying the sites where problem potassiums were drawn. Laboratory data reveals that the problem seems to be isolated to those samples collected at the main laboratory and one satellite location. In narrowing her focus to these locations, the lab manager considers what they have in common. Because samples collected at the main lab do not require a courier service to the testing facility, transport irregularities are ruled out as a source of the problem at the main laboratory. The manager turns her attention to collection personnel assigned to the sites. Can the phenomenon be traced to one or more individuals who rotate between both places? Collector information for each of the problematic samples is tracked for an extended period, but no definite pattern with personnel emerges.
Device-specific errors. As part of her evaluation, the laboratory manager asks her staff to record the type of device used during sample collection, including the gauge of the needle.
Collection errors. The lab manager reviews common collection errors with the staff including the affect fist pumping has on potassium levels. She also stresses the importance of following the proper order of draw. The manager is aware that IV fluids containing potassium can threaten sample integrity when blood is drawn from the infused arm. But because the affected draw station involves outpatients only, IV contamination is ruled out.
Processing errors. Noting all samples in question were drawn in red-top tubes, the manager observes the staff throughout specimen handling and processing. She confirms that appropriate clotting times are observed prior to centrifugation, the tubes are spun within two hours of collection and are subjected to the proper centrifugation time and RCF. All tubes are spun with their stoppers in place, and tubes emerge from the centrifuge with good gel-barrier formation with no visible hemolysis.
Conclusion. While assessing the results of her investigation, a common variable emerges. In each case where a serum potassium result was of questionable accuracy, the red-top tube tested was always the second of two red-top tubes drawn; never the first. The lab manager realizes she had not closely scrutinized the length of time tourniquets were being applied.
She reminds her collection staff of the importance of minimizing tourniquet time and the effects of hemoconcentration on test results. She then asks her staff to document tourniquet time with every draw. Because of their new awareness of this preanalytical variable, there was a dramatic and sustained decrease in the incidence of falsely elevated potassium results at both locations.
Discussion. The case study presented is based on actual investigative notes shared by a laboratory manager whose hope is to assist others facing similar challenges to quality in their laboratories. Although spurious potassium results may have various causes, this scenario illustrates the procedural steps that may be necessary to achieve a successful resolution.
[Editor's note: This fall, the Center for Phlebotomy Education will introduce SmartCharts™, our latest way to help you and your staff renew physician confidence in the results your lab releases, reclaim your productivity, enhance your quality assurance activities, and teach key concepts every student and new-hire must grasp. SmartCharts™ provide concise summaries for referencing and posting in your facility on the most error-prone preanalytical processes, including sample handling and processing, troubleshooting elevated potassium results, analyte stability, and draws during IV starts. More details will be announced in an upcoming issue.]
The To the Point® series of CE downloads provides phlebotomists and other healthcare professionals with accurate and affordable phlebotomy continuing education that is easy to use. Each download consists of multiple articles on a variety phlebotomy topics, and is available in two versions:
1) P.A.C.E.® for the individual who needs formal continuing education credit;
2) In-House Use for managers/instructors to distribute and grade as an internal education exercise for their staff/students.
Highly researched and regularly updated, all material provided is current and consistent with the latest CLSI standards and OSHA guidelines, just what you expect from the most dependable source of accurate information on blood collection procedures in the industry. Articles and corresponding test questions within each volume include:
The Center for Phlebotomy Education is an approved provider of continuing education credit through the ASCLS P.A.C.E.® program.
This Month in Phlebotomy Today
Here’s what subscribers to Phlebotomy Today, the Center for Phlebotomy Education’s paid-subscription newsletter currently in its 12th year of publication, are reading about this month:
For subscription rates and to subscribe to Phlebotomy Today, click here. The current month’s issue will be emailed to you immediately upon subscribing.
On a Personal Note... It's back!
Long-time subscribers of our flagship publication, Phlebotomy Today, will remember a regular feature in which its editor took willing subscribers far away from the usual fare of technical articles, and down a road less traveled in a series of personal essays. Well, that editor was me, and I'm back.
I never really went anywhere, but in May of 2008, after six years of monthly musings, time became an obstacle. As the demands placed on me as Executive Director of the Center for Phlebotomy Education grew, I found myself with less and less time each month to write off-topic conversations. In May of 2008, something had to give; that "something" was my personal notes.
Time is still an obstacle, but now I have help in the form of a managing editor, Lisa O. Ballance, MT(ASCP), CLC(AMT) who now does most of the heavy lifting on each issue. It is only because of her skillful research and artful writing that I am able to get back to what was for many their favorite part of the newsletter. Thank you, Lisa.
My "On a Personal Note" pieces may not be monthly, but they will be regular, I promise. Now and then I may even dig back into the archives and repost those that readers found particularly enjoyable at the time. Maybe you will, too.
To those for which these essays are new, it might be polite to let you know what you can expect should you follow me. Depending on how the muses strike me, I may be humorous or I may be poignant; I might reminisce one month and share a dream the next; I'll share my struggles and my frustrations, my joy and my weaknesses, my hopes and my victories, and my fears and my failings. And yes, I'll share my faith from time to time. So be warned. But I won't insist mine is right and yours is wrong. So be assured.
Another thing I won't do is share my politics. I'm not one of those who feels just because one has an audience one needs to influence how they think. You are my blessing, not my opportunity to advance an agenda. The only agenda I have is to help you and everyone who works with you and for you to draw blood samples properly and safely. That's it. And if you follow me on my Personal Notes, my only agenda is to make you glad you did.
Not everyone has time for such diversions, so my Personal Notes won't be contained within each issue; only linked. That way, you can quickly scroll on past if you don't have the time for a diversion. But I hope you sample at least the first few.
To reinstitute this Phlebotomy Today tradition, I thought it best to start with my very first installment, the inaugural "Personal Note" shared with my readers in October, 2002. If you have a moment, follow me.
Q: When TPA is being given into a triple-lumen catheter, we flush with 20 mL of saline, and discard 10 mL of blood. We are finding that we have unreliable results. Should we collect from one of the opposite cannulas or refuse to collect from the device period? If we opt to draw from the line, what is the appropriate protocol?
A: Neither textbooks nor the CLSI standard address the administration of the clot-buster medications like TPA in the context of a line draw. But it makes sense to have a policy that states all ports of a line into which TPA is administered should be off limits. As evidenced by your own experience with skewed results, even flushing and discarding large volumes doesn't guarantee a clean specimen.
Drawing from the opposite arm would be preferable. If not possible, draw below the IV on the same arm. Regardless of where you perform the venipuncture, pressure to the site should be applied and bleeding carefully guarded prior to bandaging.
Each month, PT-STAT! will publish one of the hundreds of phlebotomy FAQs in the growing database of questions and answers available in Phlebotomy Central, the members-only section of the Center for Phlebotomy Education's website. For information on joining Phlebotomy Central, click here.
Last month, we asked visitors to our website and our Facebook page about the steps their facilities are taking to reduce the volume of blood drawn from patients susceptible to anemia induced by diagnostic blood sampling, also known as iatrogenic anemia. Over 41 percent of those surveyed indicated that their facility has not yet taken action to reduce patient blood draw volumes. However, of this group, 27 percent noted that their facility uses previously collected samples for “add-on” tests, where appropriate.
For facilities where measures have been instituted, use of add-on tests was the most prevalent practice reported (62%), followed by use of pediatric-size evacuated tubes for susceptible patient populations (41%). Education also plays an important role with nearly one-fourth (24%) of survey participants indicating that in-services for clinicians on phlebotomy overdraws are/were conducted in their facilities. Monitoring blood volumes drawn from susceptible patients and having triggers in place that prompt action when blood volume limits are exceeded were noted by 14 percent of respondents. Rounding out the list of actions taken to decrease sampling volumes was the collection of capillary samples, which was reported by 10 percent of survey participants.
Survey participants were also asked to which patient population(s) are these measures applied. The top response was neonatal patients (64%), followed by geriatric (60%), oncology (40%), and patients being treated for myocardial infarctions (28%). Seventeen percent of respondents indicated these measures are applied to all patient populations.
Reinforcing the need to implement strategies to limit blood loss due to diagnostic sampling is a recent study appearing in the Archives of Internal Medicine. Of 17,676 patients admitted to 57 U.S. hospitals due to an acute myocardial infarction, the study revealed 20 percent of the patients developed moderate to severe anemia during their hospital stay. The average blood volume collected from those who developed anemia was 173.8 mL. Researchers found that for every 50 mL of blood drawn, the risk of anemia increased by 18 percent.
This month’s survey question:
Ernst Accepts Board Positions
The Center for Phlebotomy Education's Executive Director, Dennis J. Ernst MT(ASCP), has accepted invitations to join the editorial advisory boards of two leading laboratory publications. Editors with Advance for Administrators of the Laboratory and Advance for Medical Laboratory Professionals issued Ernst invitations to join their respective boards in August.
Ernst has written over a dozen articles for Advance publications, and has been quoted in over 30 Advance articles.
"Dennis Ernst is such a thought-leader in phlebotomy and safety, and very well-respected by peers," says Lynn Nace, Editor of Advance for Administrators of the Laboratory. "It will be a pleasure to have him part of the ADVANCE editorial advisory team."
Last Month on Facebook
During the month of August, fans and visitors to our Facebook page shared their thoughts on the following topics:
Looking for an online community to post questions or to simply satisfy your hunger for phlebotomy talk between newsletter issues? Visit and “Like” our Facebook page and you’ll never miss out on another discussion. Your peers need your input, and you need theirs.
What Should We Do?
[Editor’s Note: "What Should We Do?" gives you the opportunity to ask our team of technical experts for advice on your most pressing phlebotomy challenges. Whether technical or management in nature, we'll carefully consider solutions and suggestions based on the industry's best practices so that you and those in other facilities with the same problem can benefit, all the while maintaining your facility's anonymity. What Should We Do? is your opportunity to ask us for suggestions on the best way to handle your real-life dilemmas.]
Our response: Blind sticking is well outside of the standard of care for phlebotomy. Permitting it puts a facility at great risk for liability for patient injury. The Clinical and Laboratory Standards Institute’s (CLSI) venipuncture standard (H3-A6) clearly states:
CLSI illustrates two drastically different orientations of the vascular anatomy in its venipuncture standard. In some patients, antecubital veins are arranged in an "H" pattern, while in others it's an "M" pattern. How does the blind-sticker know which anatomy they’re dealing with?
Being well-versed in vascular anatomy isn't enough. Does the person who performs blind-sticking know where the nerves are that pass through the antecubital area? If he/she is blind-sticking, probably not.
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