Skin Puncture or Venipuncture? Pros & Cons, Part 1
One of the first decisions specimen collection personnel have to make with every patient is whether to perform a skin puncture or a venipuncture. Most of the time, a venipuncture is mandated by the volume of blood required to complete the battery of tests ordered. Other times, it's not as cut and dried. For example, a physician orders a CBC and bilirubin on a newborn. Some would argue that blood from a venipuncture is the "gold standard" and that blood from a skin puncture is subject to more preanalytical errors and less likely to be accurate. Myth or reality? In this 2-part series, we'll look at the pros and cons of each method of specimen collection. This month the focus will be on sample quality.
One of the disputable concepts, especially in the minds of physicians, is that blood obtained by venipuncture renders a more accurate representation of the patient's circulating blood than that obtained by skin puncture. This conception may be based on the presumption that all venipunctures are performed correctly and cleanly and all capillary punctures are contaminated by hemolysis and tissue fluids. Although the latter concern may be justified, when properly performed, skin punctures can render a sample just as representative of the circulation as that obtained by venipuncture. (Note: skin punctures or incisions performed on edematous sites or from dehydrated patients may not yield representative results regardless of technique.)
To assure the best sample is obtained, collectors who perform skin punctures should prewarm the site for 3-5 minutes with a warm compress not to exceed 42 degrees Celsius. Massage can also be used in conjunction with prewarming. When properly prewarmed, the flow of blood through the tissue has been reported to increase seven-fold.(1) Although some argue that prewarming takes too long to perform, advocates of prewarming argue that time spent increasing the circulation of an infant's heel can equal the time spent milking blood from a site that hasn't been prewarmed. The difference being only that the blood obtained from the prewarmed site is more likely to yield accurate results, less likely to be rejected because of hemolysis or clot formation and of an overall higher quality than that obtained without prewarming in the same amount of time.
Besides prewarming skin puncture sites, wiping off the first drop of blood makes the specimen even more comparable to venous blood. Since the trauma of the puncture or incision inevitably releases tissue fluids into the lanced tissue, wiping away the first drop is seen as a means to minimize if not eliminate the potential for tissue fluid to alter results. Except for a few bedside testing devices that require first-drop testing, collectors should wipe away the first drop that emerges from a skin puncture or incision with a clean gauze pad before collecting the specimen that will be sent to the lab for testing.
By prewarming the site and wiping away the first drop of blood, capillary blood can closely approximate venous blood in specimen quality and dispel the myth that venous blood is the only specimen that can accurately represent the patient's physiology. But keep in mind, even when capillary specimens are collected cleanly with minimal trauma, they remain a mixture of blood from capillaries, venules, arterioles with some interstitial and intracellular material, the proportion of which is dependent upon technique. Because of this composition, capillary specimens show lower concentrations of potassium, total protein and calcium and higher concentrations of glucose.(1)
But when venipunctures are performed haphazardly and without regard for the established standards, a capillary specimen can even yield more accurate results as long as other well established considerations remain intact, considerations such as properly mixing specimens containing additives during or immediately following collection. Since capillary specimens flow through ruptured capillary beds, platelets are more likely to clump together and precipitate clot formation in the collection tube than during venipuncture. Gently tapping or flicking collection tubes as they are being filled may inhibit clotting during the collection process and prevent specimen rejection. However, collectors must be adequately protected against exposure when mixing blood during collection if the collection device being used is open-ended (e.g., devices with scoop-like openings) and require filling without a cap.
Careful attention to the increased potential for capillary specimens to clot during collection can not only prevent specimen rejection, but remove a significant downside to collecting specimens by skin puncture.
Editor's Note: In September, Part 2 of this series will discuss the pros and cons of capillary collection and venipuncture in regards to patient and collector safety.
1) CLSI. Procedures and Devices for the Collection of Diagnostic Capillary Blood Specimens; Approved Standard—Sixth Edition. CLSI document GP42-A6. Wayne, PA: Clinical and Laboratory Standards Institute; 2008.
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What Should We Do?: Mixing tubes
Dear Center for Phlebotomy Education:
Mixing tubes properly is a big problem in our facility. With different numbers of inversions for different tubes, it's hard to teach and hard for our staff to retain, much less implement. We need an easier way to get the point across that will actually be incorporated into our staff's practices. If I could just simplify our procedure manuals to say that all tubes should be mixed 10 times, that would solve the problem. But some publications say 3-5 times, some 5-6, and some 8-10. I don't want to cause problems with sample quality, but we need some kind of standardization that works. What should we do?
We can understand your interest in simplifying the mixing sequence to get better compliance. But it's really not as complicated as you think.
Your reference that some say 3-5 inversions is likely pertaining to citrate tubes. It's typical for manufacturers to limit inversions for coags because excessive agitation can activate platelets, which would then release factors that could alter coag results. Also, sodium citrate is a liquid additive, which mixes much more readily, and doesn't require the same number of inversions to prevent coagulation as tubes with dry anticoagulants that adhere to the walls of the tube.
But there are good reasons some tubes should not be subjected to that many. So you really wouldn't want to apply a 10-inversion rule across the board. Nor would you want to adopt a 5-inversion rule to tubes that have dry anticoagulants for the opposite reason. The lower number might lead to rejected samples because of clotting if all the additive isn't mixed off the walls of the tube into the sample.
So you really need to apply whatever the manufacturer recommends. That's likely to be 5-8 for all tubes except sodium citrate, which requires only 3-5. Tubes for Quantiferon, however, require vigorous shaking.
So there really can't be one recommendation that works for all tubes. That's just the nature of preanalytic quality. If you're getting a lot of clotted tubes due to inadequate mixing, you need an inservice or remedial training for those whose technique is contributing to the problem. Rejected samples are a huge problem for every lab. In the case of clotted samples, it's entirely preventable.
Got a challenging phlebotomy situation or work-related question? Email us your submission at WSWDpanel@phlebotomy.com and you just might see it as a future case study. (Names and identifiers will be removed to assure anonymity.)
Product Spotlight: Lecture Collection DVDs
If you've been waiting for our industry-leading DVDs to go on sale, your patience is being rewarded. The complete set of the Applied Phlebotomy Lecture series is now half price! For the month of August only, you'll save almost $300 when you purchase the following titles as a set:
- Seizing Control of Blood Culture Contamination Rates
- Ending Hemolysis in the ED... and Everywhere Else
- Mastering Pediatric Phlebotomy
- Potassium Results Your Physicians Can Trust
- Delivering World-Class Customer Service
- Successful Strategies for Difficult Draws
The six-set Applied Phlebotomy Lecture Collection is a series of studio-recorded adaptations of presentations given by Dennis J. Ernst MT(ASCP), NCPT(NCCT), the Center for Phlebotomy Education's director. The DVDs were produced in 2014 and 2015, and are in use at healthcare facilities and educational institutions around the world. All titles still reflect the current industry standards. According to Ernst, these titles will not be affected by the upcoming revision of the CLSI venipuncture standard, expected to be released in the spring.
"The information on these DVDs is timeless, and represents the body of knowledge for each subject," says Ernst. "Being immersed in the preanalytic realm, we have spared no expense to make these as accurate and comprehensive as possible. We know budgets are tight, and want to make sure every educator and manager has access to this critical information."
Each DVD provides access to an online CE exercise educators can use to assess comprehension as an in-house CE exercise. P.A.C.E. continuing education credit is also available for a nominal additional fee.
From the Editor's Desk
One week ago, the Phlebotomy Channel launched the world premiere of the 3rd edition of Basic Venipuncture, the industry's best selling phlebotomy training video.
The process started 18 months ago when I started looking for a production company. One after another came to our offices and did their tap dance. One after another tripped over their own feet. It took six months, but I finally turned to our local NBC affiliate and found they had a department that did outside production. They turned out to be the best production crew I could have ever hoped for.
When you're filming a medical training video for a procedure as highly technical and detailed as a venipuncture, the tiniest details have to be perfect in every regard. Not only am I a perfectionist when it comes to training materials, our customers (that would be you) demand perfection and know what it looks like. So it's no wonder there were seven sessions filming five actual venipunctures, 15 script revisions, 12 rounds of post-production edits, eight actors and hundreds of hours of preparation, execution, direction, and reviewing footage.
The only thing that stands in the way of this project and you being able to use it where you work and teach is subscribing to the Phlebotomy Channel or waiting for the DVD, which we anticipate being ready to release in October.
I think you're really going to like this revision, mostly because it's entirely new. The easy road for us would have been to simply update the content from the second edition that was impacted by the revised CLSI venipuncture standard published last year. Truth be told, only three minutes of the 32-minute video needed to be updated. But you know us well enough by now to know we don't "cheap out" when it comes to creating our educational materials.
Besides, I know many of you have been using Basic Venipuncture since it first came out in 2004. You've seen the same images, watched the same animation, and heard the same narrator read the same lines hundreds of times as you show it to class after class, student after student, and new employee after new employee. You probably have it memorized.
We thought you need something entirely new and fresh. We're not about regrinding hash and pawning it off to you as a new dish every time you enter our "restaurant," we're about creating a new culinary feast with fresh ingredients. That's what you want; that's what you deserve; that's what you're getting.
I am especially grateful to Alan Elliott, the laboratory administrator at Baptist Floyd Health in New Albany, Indiana for making his facility available for all five filming sessions. Alan and his staff were exceptionally accommodating throughout the four months of filming. Not only that, but we were able to talk him into putting on a hospital gown and playing patient. It's the only time you'll ever see Alan Elliott laying down on the job. We're also grateful to Greiner Bio-One and VeniStat for providing educational grants.
There are hundreds of changes in the revised venipuncture standard issued last year. This is the only video that reflects the current version, the version to which you and your staff and students will be held accountable. Basic Venipuncture has been the gold standard in phlebotomy training videos for 14 years, and has been shown in thousands of healthcare facilities and academic programs worldwide. This will be the first video in our Applied Phlebotomy series filmed in high definition. That means with this revision the gold standard shines like never before.
If you don't already subscribe to the Phlebotomy Channel, you can wait until October for the DVD. But if you're an early-adopter and have to have the latest and greatest when it hits the street, subscribe now and you, too, can be on the bleeding edge of phlebotomy education, so to speak.
Personally, I've never been an early adopter. I always wait to see what the market thinks of a new product before I invest. That's why I've never bought a Pet Rock, laser disc or frozen entrees from Colgate. On the other hand, I was also slow on the uptake when cell phones and Blackberrys first came out. I'm getting better, though. I just updated my windows operating system from having to slide the pane up to opening it with a crank handle.
Dennis J. Ernst, editor
Standards Update: Sample labeling
The newly revised venipuncture standard released by the Clinical and Laboratory Standards Institute in April, 2017 is the most comprehensive revision in the document's history. With over 140 new mandates, facilities have a lot of changes to implement. This series discusses one or more substantive changes each month.
You pride yourself in strictly adhering to the standards and your facility's policy on patient identification. You realize a mistake in this first step of a blood draw can kill a patient, so you make no exceptions. Not ever. You've seen how devastating it was for others throughout your career, and you have vowed never to let that happen to you, or any patient you draw. You have never misidentified a patient, and you probably never will.
But patient identification errors are not the only type of deadly ID error those who draw blood samples commit. Tube-identification errors can be just as deadly.
According to the latest version of the CLSI venipuncture standard, released one year ago this month, those who draw and label blood samples must compare the labeled tube to the patient's ID band before leaving the patient. If your patient is an outpatient in a facility that does not routinely put ID bands on outpatients, the standard requires you to show the labeled tube to the patient and seek confirmation that the information on the tube is accurate. If the outpatient is not capable of confirming the label on the tube (e.g., if the patient is sedated or otherwise cognitively impaired, has a language barrier, is an infant, etc.), the collector must have a caregiver, friend or family member confirm the information on the patient's behalf.
In many facilities, phlebotomists leave the laboratory with preprinted labels for a multitude of patients, especially for morning draws. Meticulously assuring the patient is the right patient does not guarantee the label they put on the tube is the right label, though. By comparing the tube with the ID band or securing patient confirmation, potentially deadly ID errors are prevented on the front and back end of the procedure.
Editor's note: Readers are urged to obtain their own copy of the standard as soon as possible and begin implementing all new provisions immediately. The document, Collection of Diagnostic Venous Blood Specimens (GP41-A7), is the standard to which all facilities will be held if a patient is injured during the procedure or suffers from the consequences of an improperly performed venipuncture. It can be obtained from CLSI or the Center for Phlebotomy Education, Inc.
Phlebotomy CE Day 2018: San Francisco
The Empowered Healthcare Manager
Every month we run an excerpt from our editor's popular blog, The Empowered Healthcare Manager.
In healthcare, the wall between laboratory and nursing departments is legendary. Call it "professionism." To nurses, lab people just don't get it. To the lab, nurses just don't get it. They're both right, and they're both wrong.
They're both right because the other side really doesn't get it. (If they got it, there wouldn't be a wall.) They're both wrong for pointing fingers instead of trying to get it.
Nursing personnel provide 90+% of direct patient care; laboratories provide 70% of the physician's objective information that guides their decisions. From a patient's perspective, when these two stakeholders of their care do not work in harmony, 100% of their care is compromised. It's a lose-lose-lose proposition. The worst part if it all is that when these two groups do not to work in harmony, it's because they choose not to. That's beyond sad.
Facilities that are the most successful in tearing down this Berlin Wall of Healthcare are those that choose not to tolerate professionism. They are extreme communicators. They interact on purpose, not just because their paths cross. They view the wall as the impediment to quality care, not each other, and unite to obliterate it. They know every brick, why it's there, and how to remove it. Then they remove it. Brick by brick, the wall comes down.
The walls between departments didn't go up easy, and won't come down that way either. Professionism is the mortar. Erradicate it and the wall tumbles down under its own weight. That's when lose-lose-lose becomes win-win-win.
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Tip of the Month: One Touch Too Many
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