Validating Temperature Indicators: The “Return to Refrigerator” Challenge

Learn more in this VUEPOINT about indicator comparison tests we conducted based on reports from blood banks experiencing indicators “tripping” after returning blood products to the refrigerator

by Jeffrey Gutkind, Temptime

We are often called on by blood banks to answer questions about temperature indicators and support their validation requirements.  They also interface with us when they are having “issues” with an indicator, whether it’s Safe-T-Vue or a competing product, and are looking for insight and possible solutions.

Temperature indicators “tripping” after return to refrigerator

Several times over the past year we’ve interacted with blood banks experiencing a specific temperature indicator problem.  Here’s how it goes – the unused blood is returned to the blood bank and the indicator shows that it is still in compliance, that it hasn’t exceeded its 10oC indication temperature.   Great!  So, the blood is returned to the blood bank refrigerator for future reissue.

Then, at a later time, the when the blood is removed from the refrigerator for reissue –the indicator has “tripped” or turned color.  How could this be?  If the temperature was in compliance going IN to the refrigerator, how could it then be out of compliance AFTER being refrigerated?

The “Return to Refrigerator Challenge”

Blood Temperature Indicator Comparison

Figure 1: “Return to Refrigerator Challenge” Temperature Indicator Test Setup

In response to this influx of concern from blood banks, we decided to conduct a comparison test.  Fortunately, we had an opportunity to work with a major university medical center to gather validation data focused specifically on the “return to refrigerator” portion of the blood product’s journey. We refer to this test as the “Return to Refrigerator Challenge.”

The purpose of the challenge was to simulate a typical blood product journey – blood being issued to another department, such as the OR, and removed from the cooler for a brief period of time, and then returned to the blood bank.   A temperature probe would be placed in the blood bag, and the performance of two types of 10oC indicators would be compared.

  1. A probe was inserted into a (simulated glycerol-water) blood bag, which was placed in the refrigerator until it reached 4.2oC.
  1. The bag was removed from the refrigerator. Five Safe-T-Vue 10 indicators and five ‘Indicator A’ were affixed to the blood bag. (Figure 1)
  1. The blood temperature was allowed to reach 8.5oC. The indicators were observed and observations recorded (Figure 2).
  1. The blood bag was placed back in the refrigerator at 4.2oC (to simulate blood being returned to the blood bank for reissue) for 30 minutes.
  1. After 30 minutes, the blood bag was removed from the refrigerator. The indicators were observed and observations recorded (see Figure 2).

Figure 2: “Return to Refrigerator Challenge” Indicator Pass and Fail Data

*Note: Accuracy of Safe-T-Vue 10 is +/- 0.4oC and published accuracy of Indicator A is +/- 0.5oC

Challenge proves need to validate indicator performance throughout journey

Comparing the performance of the two indicators (Figure 2), it was apparent that the Safe-T-Vue indicator had accurately performed as expected and within the specifications.   Two of five ‘Indicator A’ had prematurely indicated (at 8.5oC) prior to refrigeration, and all five had failed to perform to specification after refrigeration at 4.2oC for 30 minutes.

Based on the manufacturer’s published accuracy specifications, Safe-T-Vue performed successfully, whereas ‘Indicator A’ failed to perform to specification.  Not only did 2 out of 5 ‘Indicator As’ “trip” at 8.5oC, all five of the indicators had tripped within 30 minutes of being refrigerated at 4.2oC.   This may be due to Indicator A’s published “stop temperature” of 8.0oC.

Is it necessary for you to conduct your own “challenge?”

This “return to refrigerator challenge” proved that the Safe-T-Vue indicator could be validated for returning blood products to the blood bank. If you have confidence in the performance (to specification) of the indicators you are using, then you probably don’t need to conduct your own “challenge.”  But, if you’ve had issues like we described early in this VUEPOINT, where indicators are mysteriously changing while under refrigeration, you may want to conduct the “challenge” to be certain that the indicators are performing as specified.

Validate critical points in your process to confirm indicator performance

The typical, standard validation should help you identify indicators that do not perform to specification (for example the two Indicator A’s that tripped at 8.5oC, which does not meet the published specification of +/- 0.5oC).   The closer look of the “challenge” could be used to confirm additional failure to perform to specification, particularly in situations where the indicator performance seems odd or questionable.

As always, we welcome your feedback on this topic.  And if we can provide validation support or help you address any temperature indicator issues, please contact me.

Jeffrey Gutkind

HELP not HYPE: Being truly useful to blood banks

VUEPOINT posts and website top-ranking pages prove that delivering blood bank help is timeless and valuable

The Williams Labs web site was created with a single goal – provide a place where people involved in blood banking can find information to help them perform their jobs more easily and with better results.

We are delighted that blood bankers from around the world – some who are Safe-T-Vue users and some who are not – routinely visit williamlabs.com and read our VUEPOINT posts because we are providing relevant, useful and helpful information for blood banks.

AABB_Temperature_Standards_2016We’ve also been flattered to learn that blood bank inspectors point blood banks to our website as an easy source of information regarding transport and storage of blood products.

In this VUEPOINT, we share the links to these pages and posts as a quick guide to these informational resources. Maybe they are handy to bookmark for your daily blood bank operations – or perhaps in orienting a new employee? Whatever your reason, it’s here for you and your blood bank staff – with our continued focus on helping you do your best.

Top 5 Useful and Helpful Pages

1. AABB Temperature Standards for Blood Products: Storage and Transport
This table provides fast access to the newest 2016 AABB Reference Standard 5.1.8.A for storage and transport temperatures of blood components.

2. Simulated Blood Product RecipesSimulated_Blood_Products_Validation
We first published this VUEPOINT almost 4 years ago, and based on the web statistics, it continues to be a valuable resource for blood banks. Did you know that 10% glycerol in water is NOT “one size fits all?” You might want to read this one and learn more.

 

3. QA Documents
It doesn’t sound glamorous or intriguing, but the incredibly useful nature of having QA documents for the Safe-T-Vue products easily accessible 24/7/365 has proven to be a winner. No hype, just help.Safe-T-Vue_QA_Docs

4. Category: Storage of Blood Components
This page provides titles and excerpts of all the VUEPOINT posts in the category “Storage of Blood Components” that we’ve published over the years. Scroll down the page and you’ll quickly find information on IR Thermometers, Cooler Validation, Refrigerator Setpoints, Indicator Comparisons and more.

5. Tags: Blood Temperature
Similar to #4 “Storage of Blood Components” this page presents almost 5 years of VUEPOINT posts that have something to do with blood temperature – measuring, monitoring, and managing.

We are always looking to learn from you – about how we can be more helpful and genuinely useful by providing valuable information to blood bankers worldwide. If you have suggestions for VUEPOINT topics or questions you’d like for us to explore – and share – we would be delighted to hear from you.

Sincerely,

Jeff Gutkind

3 Things You Need to Know

About Blood Temperature Indicators

Do you trust a product to protect your blood supplies that may “auto activate?” Would you be discarding expensive blood products because of an unreliable indicator?

1. Accuracy Matters

Of the indicators on the market, one is clearly less accurate. “Indicator A” can reach endpoint at 9o, resulting in wasted blood – blood that may actually be in compliance.

2. Performance Varies Greatly

The fine print for a competing indicator clearly states that AFTER ACTIVATION, the temperature of the blood needs to be brough back down to its 8oC “Stop Temperature” to avoid premature indication.

This means that the indicator could prematurely indicate at a temperature as low as 8oC if the blood bank doesn’t take the extra step to ensure that the blood – after attaching an activated indicator – is cooled below this “stop temperature.”

3. Lower Price May Not Be Lowest Cost

Comparing indicator purchase price may make it seem like an easy choice.  however, the actual COST of an indicator that is:

  • poor performing
  • less accurate, or
  • unreliable

is dramatic in comparison to the cost of wasted blood products.

Knowing that, on average:

  • blood banks receive a significant amount of issued blood back
  • ONE unit of wasted blood may cost the blood bank $250
It only makes sense that a more reliable indicator that reaches endpoint at 9.6oC (and not as low as 8.0oC) is a more cost effective choice.

Handy Tip

Safe-T-Vue lot-by-lot QA documents are posted here on our website for easy customer access – and prove that Safe-T-Vue is manufactured to quality standards.

 

IR Thermometers: Determining Blood Product Temperature on Return to Blood Bank

Learn as we explore common misconceptions about IR thermometers and surface temperature vs. core temperature

The following PathLabTalk post describes something we encounter repeatedly in blood banks – and illustrates several problematic misconceptions about determining blood product temperature on return to the blood bank. At the same time, this post demonstrates a reliable, good practice!

“Our transfusion service is looking for an infrared thermometer that we can use to determine the internal temperature of our donor units. We issue products in validated coolers to surgery, ED, and other locations and sometimes we receive the products back that have not been used. Currently, we attach a temperature indicator to the unit, but want something more accurate that is not difficult to operate, calibrate, etc….”1

First, we congratulate this PathLabTalk poster for reaching out to the blood bank community for ideas and support. She/he has realistic, everyday needs that many may identify with. In this VUEPOINT, we present some problems and misconceptions, along with this blood banker’s good practices, that are communicated in the post.

Problem #1
Infrared Thermometers (a.k.a. Infrared “Guns”) do not measure “internal temperature”

Infrared thermometers are used to measure surface temperature without contacting the product being measured. Most specifications for these devices state “non-contact surface temperature measurement.” They do not measure “core temperature” of any product, including blood. Infrared thermometers are used in many different applications ranging from food service, to residential heating/cooling, to industrial. Typically they are used for “hard to reach” areas where contact temperature measurement is difficult/impossible.

Problem #2
A one-time temperature reading of a returned blood product provides little assurance that the blood was kept at the correct storage or transport temperature over the entire time period that it was out of blood bank control.

No matter how well everyone is trained and how conscientious they are, we all know that once the blood product leaves the blood bank, anything can happen. For example, in the OR or ED there are many critical functions being performed at once, and often over long periods of time. Blood can be taken from the cooler and left on a table for hours – and then returned to the blood bank, having had time to “cool” to what may appear to be an acceptable temperature.

The precariousness of this situation is compounded when an IR thermometer is used to check SURFACE temperature when the product is returned.
• Perhaps the blood bag was placed on an OR table for 6 hours during a long procedure, but was placed back in the cooler just long enough for the SURFACE to cool to a seemingly “acceptable” temperature…?
• Is it safe to assume that the blood temperature never reached unsafe temperatures?

Problem #3
Accuracy of IR Thermometers is affected by how they are used – due to “Distance to Target” A.K.A. FOV (Field of View) or D/S Ratio (Distance to Spot)

Accuracy specifications for most IR thermometers range from +/- 1.0oC to +/- 2oC. Looking at a few models from major manufacturers, their D/S specifications are documented as: 1 meter, 1.5 meters and 2 meters – which might surprise blood bankers using IR thermometers. The distance between the device and the target (blood product) affects the reading accuracy – and also means that the dependability and repeatability of temperature readings is “user dependent” in how they use the IR thermometer from variable distances (you’ll read about this problem in the PathLabTalk post responses). If you’d like to learn more about this particular characteristic, Grainger (industrial and facilities maintenance equipment resource) has an excellent “Quick Tip” on IR thermometers.

Good Practice

Temperature indicators provide irreversible visual evidence if the blood product exceeds its specified temperature, even if the product is “re-cooled” prior to return to the blood bank.
Attaching an irreversible temperature indicator to the blood product, as done by the PathLabTalk poster, IS one way to know if the blood was maintained at correct storage/transport temperatures. When the blood product reaches the indication temperature (typically 6oC or 10oC), the indicator provides “irreversible” visual evidence of the temperature excursion – even if the blood product is “re-cooled” after being out of blood bank control.

This elicits a similar question that we raised regarding IR thermometers – do temperature indicators that adhere to the surface of the blood product provide indication of the surface temperature or core temperature?

Safe-T-Vue indicators (Temptime Corporation) are chemical indicators, and the algorithms that are used to formulate them are based on thousands of laboratory tests that incorporate the CORE blood product temperature. While the indicator may be applied to the surface, its color response is correlated to core temperature.

Why this all matters

Bacteria are very rarely transmitted during blood component transfusion, but if they are, they usually cause severe, life-threatening adverse reactions, with the mortality rate of 20-30%.2

Periodically, there are reports of incidents likely to have caused serious injury or death, that have been linked to bacterial sepsis from blood products that were dispensed for extremely long surgeries, and returned to the blood bank unused.3 Those very products could be returned to inventory after checking the temperature with an IR thermometer, and reissued to another patient. Unbeknownst to the blood bank, the blood products may have reached temperatures that allowed for contaminants to thrive. When that unit is then reissued and transfused to the next patient, the results can be catastrophic.

Kudos to the PathLabTalk poster for good practice

In summary, we understand that it’s unrealistic to assume that blood products will be handled outside of the blood bank with the same watchful eye and expertise that trained, focused blood bankers have. And there is little certainty of blood product maintenance at appropriate storage/transport temperatures, even when using a temperature sensing device to check the product on return to the blood bank.

The most sure way to know that the blood did not reach non-compliant temperatures – that could result in bacterial sepsis – is to use an irreversible temperature indicator that stays with the blood product during its entire time out of the blood bank – as the PathLabTalk post noted.

References
1. http://www.pathlabtalk.com/forum/index.php?/topic/6436-infrared-thermometer/

2. http://cdn.intechopen.com/pdfs-wm/27955.pdf

3.  http://www.jsonline.com/watchdog/watchdogreports/problems-at-hospital-lab-show-lax-regulation-hidden-mistakes-b99585186z1-330324081.html

Tips for Better Blood Handling

Lessons you’ve taught us – and why they work!

Keeping blood cold can be a challenge. Here we present a few EASY handling procedures that can be readily incorporated into the day-to-day receiving and dispensing of blood in your blood bank – and make a significant difference.

You told us in our late 2013 survey what topics were of most interest to you and your colleagues in the blood bank. The most popular choices – by a large margin – were:

  1. Proper handling of blood products, and
  2. Use of temperature sensors in blood transport to the OR and ER/Trauma

Reflecting on the conversations and comments from visitors to our booth at the 2013 AABB in Denver, this survey validated what many of you have told us about keeping blood cold and proper handling.

In this VUEPOINT we are summarizing some of the handling procedures and ideas that blood bankers from around the world have shared with us over the years.

Tip #1

Handling blood bag by edges to prevent warming blood product Always handle blood bags by the ends where there is no blood that may be warmed by normal handling.

Why?

Holding a typical 300 – 400 cc blood bag in warm human hands for even 20-30 seconds may raise the core temperature by up to 2°C. The temperature rise is faster in smaller bags (< 350 cc) so extra care should be taken to handle small bags only by parts of the bag where no blood may be warmed by handling.

Tip #2

Always keep cold packs in the blood refrigerator. Place blood bags on a cold pack immediately when removing blood from the refrigerator – MAKE IT A HABIT!

Why?

A 350 cc blood bag that starts at 3.5 °C will reach 6.0°C in approximately 6 minutes and approximately 10°C in approximately 19 minutes depending on the temperature of its environment, and the temperature of any surface it comes into contact with (hands, lab bench, etc.).

The same bag on a cold pack, where both blood and cold pack are at 3.5°C and placed on a bench at 20°C will keep the blood below 6.0°C for approximately 14 minutes and below 10.0°C for approximately 36 minutes.

This is a no-brainer! USE COLD PACKS.

350 cc Blood Bag, temperature change with and without cold pack
3.5 °C 6.0°C 10°C
Without Cold Pack START 6 minutes 19 minutes
With Cold Pack START 14 minutes 36 minutes

Tip #3

Using an adhesive temperature indicator on the blood bag is one way to monitor – and be assured – that the blood temperature has not exceeded the upper compliance temperature of 6.0° C or 10.0°C.

Why?

Adhesive temperature indicator on blood product gives visual indication

Indicators give visual indication when the blood is approaching the 6°C or 10° C compliance temperature, and then confirm if the blood exceeded temperatures – even if the blood is “re-cooled” to a compliance temperature.

QUICK ACTIVATION TIP

Temperature indicators on blood bags in blood bank refrigerator

Some blood banks have adopted a procedure to apply the indicators to blood bags as they are put in blood bank refrigerator storage – then they can quickly activate the indicator immediately when the blood is dispensed, or activate it at the same time it is applied.

VALIDATION TIP – When validating a blood indicator be certain to use a temperature recorder that measures and indicates to within 1/10th of 1°C accuracy (0.1 °C).

 

SELECTION TIP – When choosing an indicator, be sure to pay attention to and ASK FOR proof that the product has been cleared through the 510(k) process by the FDA. This can be verified by receiving the product’s FDA 510(k) registration number from your supplier. To learn more about FDA 510(k) registration, read this VUEPOINT.

 

Do You Have Any Tips To Share?

  • Are there other procedures or ideas from your blood bank that we can share?
  • Do you have unanswered questions that we can help you get answers to?

Your peers, in hundreds of blood banks around the globe, are always eager to learn from each other. Please pass on your Tips for better blood handling, and we will be sure to post them in the next VUEPOINT.