But Why? Fingersticks and Common Sense

In my hospital nurses were required to order a stat lab serum glucose whenever they had a critically High or Low Fingerstick result. My question was...Why?

But Why? Fingersticks and Common Sense

Ordering a Stat Serum Glucose to Confirm Glucometer (Fingerstick) Reading

This is a case where the policy did not seem to make sense.

At my facility, the blood glucose monitoring procedure called for the nurse to order a stat serum glucose in the event of a critically low or high fingerstick value.

(Critical blood glucose values at my facility are defined as less than 50 mg/dL or greater than 500 mg/dL for adults and less than 25 mg/dL or greater than 200 mg/dL for neonates).

Let's say you perform a fingerstick on your adult patient which results in a value of 48 (critically low value). According to the procedure, you would immediately call Lab for a stat serum glucose. If the patient were symptomatic, you would also immediately implement the Hypoglycemic Protocol and administer either D50 or oral carbs, depending on if they can safely swallow or not.

As an educator preparing to do competency testing at our annual Skills Fair, I, of course, planned to teach from the policy and procedure- but I have to say, this made no sense to me.

My question was "What is the rationale for ordering a stat serum glucose when the fingerstick result is critically low or high?" I asked several key people in Lab and Nursing.

Here are 3 conversations I had with various decision-makers while attempting to understand the rationale:

Conversation #1

Me: "What is the rationale for ordering a stat serum glucose when the fingerstick result is critically low or high?"

Answer: "To verify the low result"

Me: "Samples must be drawn at the same time or within a few minutes of each other to have a valid comparison. How long does it take Lab to get to the floor for a stat? Realistically?"

Answer: "For a stat? 15-30 minutes"

Me: "Right....."

Conversation #2

Me: "What is the rationale for ordering a stat serum glucose when the fingerstick result is critically low or high?"

Answer: "Well, the machine might be wrong. We have to check it"

Me: "Actually our machines are top-performing and we have the most recent model. They even correct for low hemoglobin and hematocrit. They are checked regularly by Bio-Medical Engineering and Quality Controls (QC) are performed every 24 hours. If we assume the glucometers are inaccurate perhaps we shouldn't use them on patients."

Conversation #3

Me: "What is the rationale for ordering a stat serum glucose when the fingerstick result is critically low or high?"

Answer: "We don't want to treat a patient if it's wrong"

Me: "Oh..except...wait, we do treat them based on the fingerstick results. Our protocol/policy says to treat symptomatic hypoglycemia. Are you saying we should wait for Lab to come draw and call the result before we give D50 to a symptomatic hypoglycemic patient ?"

In the end, the only real argument was 'Well... because we've always done it that way"

My colleague and fellow Educator Debbie and I embarked on a mission to change the policy. Our goal was to ensure patient safety, and to not impede nurse workflow with unnecessary interventions.

We know that blood glucose values can change quickly depending on the clinical condition of the patient. We sought out Lab's expertise and discovered that glucometer results are considered to be accurate and acceptable if the comparison serum glucose specimen s within 15 mg/dL for results less than 75 mg/dL or +20 mg/dL for glucose results greater than 74 mg/dL.

We re-wrote our policy accordingly. Now it reads: "If a critical value is obtained":

  • Repeat the (fingerstick) test to confirm the result
  • If test result is not confirmed, i.e., the second test value varies by more than 10%, obtain a stat Lab draw
  • Notify MD if test is confirmed and the result is outside expected parameters for that patient
  • Select or enter a relevant comment in the glucometer
  • Follow Hypoglycemia Protocol for symptomatic patients

It makes sense and allows the nurse to intervene quickly and care for his/her patient.

Take a look at your policies. If they don't add value, don't help patients and/or aid in nurse workflow... it may be time to make a change!

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Nurse Beth

About Nurse Beth, MSN

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Nurse Beth works in acute care and is the career guru at the Ask Nurse Beth career advice column. She has an award-winning blog, nursecode.com

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Specializes in Travel, Home Health, Med-Surg.

This is the same policy at the hospital I work at, never made sense to me either. Even though nurses do recheck the sugar with the glucometer we are still required to obtain a STAT lab. So, before treating the patient we 1) call lab (who of course is too busy to come), 2) hunt down supplies to draw lab ourselves, 3) recheck glucometer again (might be different after all that time), 4) actually treat patient on results. I don't know about you, but I prefer to treat the patient FIRST based on glucometer readings and patient s/s. After all this the patient could be in a coma...doesn't make sense...

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Specializes in GENERAL.

Drawing a serum blood glucose for an ultra high FS reading sounds reasonable to me.

Comfirmation is the key and and as matter of good practice all wacko blood values should be evauated with at least two jaundiced eyes.

On the other hand if someone did a FS on me dead-on as portrayed in the graphic for this story, Cat-scan should be notified stat for someone to be ruled out for a closed head injury.

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Specializes in Oncology.

The reason is because glucometers become less accurate in lower ranges. In very high blood glucoses, a meter may not even be able to report a result. For immediate treatment it is important to treat the patient, but accurately gauging how severe the hypoglycemia was may be important for considering further treatment changes or risk to the patient moving forward.

You may find this article interesting. It talks T length about the technical challenges related to accuracy of blood glucose meters- mainly related to sample size and the differences between capillary and venous blood. I'd also like to turn your attention to the accuracy parameter section, though.

" For instance, the International Organization for Standardization and the U.S. Food and Drug Administration has set accuracy criteria to ±20 mg/dl (1.11 mmol/liter) for levels 100mg/dl (5.6 mmol/liter) for at least 95% of results."

Plus or minus 20 if you get a meter glucose reading of 43 means the plasma glucose is somewhere between 23 and 63. That's a clinically significant difference, no?

There are other accuracy standards, but the hypoglycemia range is consistently allowably the least accurate due to the limits of the technology.

Read the article. I think you'll have a better understanding of why this policy exists.

Glucose Meters: A Review of Technical Challenges to Obtaining Accurate Results

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Specializes in Nephrology, Cardiology, ER, ICU.

Great article. Agree we need to use evidence based practice and delete the phrase "because that's the way we've always done it" from our vocabulary

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Great discussion-this has interested me before. I am interested in what others have experienced in this area. It was always my understanding that fingerstick is not as accurate as serum. I have certainly seen differences between the two numbers. Although not usually drastic, it is nice to have the most accurate number possible when planning the overall care of the patient, I would think. Especially in instances such as DKA or HHS.

Thanks blondy2061h, MSN, RN for the article on the meters.

Here is a link to a study that was done in a ICU between bedside fingersticks versus plasma from the Journal of Intensive Care Medicine:

Accuracy of bedside capillary blood glucose measurements in critically ill patients | SpringerLink

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Blondy2061h - best answer.

This can also be applied to other POC devices like the iSTAT and pulse oximeter. Accuracy can vary in different situations. This is also why many labs are repeated as soon as a patient arrives at a hospital even if they were just done enroute by the transport team. Or, prior to initiating or verifying the treatment they initiate, the team will do the labs at the other hospital with the main lab or a POC device calibrated and used in an ideal environment.

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Specializes in critical care, ER,ICU, CVSURG, CCU.

If patient receiving IV vitamin C , finger stick glucose monitor sticks not accurate, that being said most are. Not on a form of IV Vit c...,,

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Specializes in retired LTC.

Just bringing up another perspective - in LTC we freq get the abnormal HIs and LOs. We don't have the luxury of any confirming STAT lab. We just repeat and proceed with whatever our standard of practice called for.

No offense, but it sounds like 'much ado about something'. I mean why would a STAT lab be so necessary for a hospital setting but not be viewed as just as critical for a LTC setting? Is LTC second class? Aren't our pts just as 'worthy' of this new attempt at 'evidence-based practice'?

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No offense, but it sounds like 'much ado about something'. I mean why would a STAT lab be so necessary for a hospital setting but not be viewed as just as critical for a LTC setting? Is LTC second class? Aren't our pts just as 'worthy' of this new attempt at 'evidence-based practice'?

It is a safety policy across the board since treatment initiated might include insulin drip or other drips which are outside of a LTC setting. I also bet if in doubt you ship out for the hospital to verify your clinical assessment and lab value.

Some policies have to be standard in a hospital since many patients are new to us and are acute which means their disease processes have yet to be defined as well as all the acute treatments including medications which cause changes in labs. Hopefully by the time the patient has is ready for LTC, the known disease processes are stabilized and your clinical judgment catches the abnormals.

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Specializes in orthopedic/trauma, Informatics, diabetes.

If we have a critical high or low, we retest and treat. I have 2 T1 sons. If i waited 15-30 minutes to treat a low, they could end up in a coma. We retest and treat, symptomatic or not (for lows). Always treat for the low immediately.

For highs they treat, if it is over 500, they are going on an insulin gtt. Our high to notify provider is 350/lows

I don't deal with a lot of adults with DKA b/c they would be in ICU. My son was in PICU for dka 2 weeks ago, they test for ketones every void test BG every hour while on insulin gtt.

I am at very large teaching hosp. Even a stat blood test would take too long. two fingersticks would be enough.

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Specializes in Oncology.
Just bringing up another perspective - in LTC we freq get the abnormal HIs and LOs. We don't have the luxury of any confirming STAT lab. We just repeat and proceed with whatever our standard of practice called for.

No offense, but it sounds like 'much ado about something'. I mean why would a STAT lab be so necessary for a hospital setting but not be viewed as just as critical for a LTC setting? Is LTC second class? Aren't our pts just as 'worthy' of this new attempt at 'evidence-based practice'?

Care in lots of settings is tailored to what is available there. Patients in small rural hospitals are not "second class" but a lot of times they're treated differently than at tertiary care teaching hospital due to availability of resources.

Further, if a patient is in LTC vs acute care a certain level of stability is assumed. You wouldn't seen someone to LTC needing q2h glucose checks with an insulin drip.

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