What is “stop temperature?”

Return to Refrigerator Challenge” generates new questions from blood banks

This was the most common question we received from blood bankers in an unprecedented response to our January 2017 VUEPOINT.  In that issue of VUEPOINT, we shared the results of a “Return to Refrigerator Challenge” – where a major university hospital conducted a test to compare two blood temperature indicators.  Their intention was to evaluate indicator performance when unused blood was returned to the blood bank.

Although this was the first time we discussed stop temperature in a VUEPOINT, it’s not the first time we’ve received questions about it from our blood bank contacts. To address those issues, we researched what stop temperature means for indicator manufacturers who use this specification. We found that stop temperature appears to relate to the chemical indication behavior.  This means that if the blood product temperature is below the stop temperature, the indicator does not change color.

How does a 10oC indicator with an 8oC stop temperature behave?

The 10oC indicator used in the challenge has a specified stop temperature of 8oC.  If the blood product begins to exceed the stop temperature (8oC), the 10oC indicator’s chemical indication material melts back to its liquid state. This melting reaction gives users a visual indication that the blood product is no longer in compliance. This type of indicator may signal that the blood product is out of compliance once it exceeds 8oC, even if it never reaches 10oC, as shown in this example.

What does this mean to blood banks using a stop temperature type indicator?

Now that we understand what stop temperature is, the question is what does the specification – and indicator performance – mean to blood banks?  Specifically, what happens if the blood product is hovering around the 8oC stop temperature for any period?

Tests shared by blood banks, combined with our studies, have shown that under a wide range of exposures and times – once the indicator exceeds its stop temperature of 8oC, the indicator may be irreversibly tripped.  In multiple tests, the blood product temperature was being internally monitored to confirm that it remained below the indication temperature of 10oC before being returned to the blood bank refrigerator.  After the blood bags were returned to the refrigerator for reissue, many indicators had tripped during the refrigeration period.

Comments and questions from blood banks based on findings

  • “Doesn’t this make it an 8oC indicator?”
  • “We have many bags that are returned to the blood bank at 8oC and they look OK. We put them in the refrigerator and they show overheated.  This is an 8oC indicator.  We are throwing out good blood.”
  • “This did not show up in the standard validation, and it never occurred to us to try this while performing the validation. After performing the ‘return to refrigerator challenge’ we found that the indicator just did not perform”.

We are grateful for comments and questions like these because they help fuel our blood indicator knowledge and testing.  Clearly, the “stop temperature” specification may be new to many blood banks and is something to be further explored.  Please share your experiences and observations so we can continue learning together.

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.

 

The Results are in: Platelet Indicator Survey

65% would definitely use a platelet indicator, and another 12% said “maybe” or in special situations

Thank you to the 115 of you who participated in our October survey about platelet management and provided your feedback on a platelet temperature indicator. We’re excited to share what we learned….. and even more excited to tell you what we plan to do about it!

A few fast facts from the survey:

  • 65% would definitely use a platelet indicator and another 12% said “maybe” or in special situations

  • 80% of those who would use an indicator want a dual range indicator (20-24oC)

  • Reasons for not returning unused platelets to inventory (most common comments): (1) Time out of blood bank, (2) Uncontrolled/unmonitored environment, including temperature and lack of agitation and (3) Spiked bags, defaced labels

  • 75% of respondents take platelet temperature on return to the blood bank (but few have temperature monitoring during the time period the platelets are out of blood bank control)

The complete Survey Results are presented at the end of this VUEPOINT post.

Interest confirmed at AABB

To further explore the topic, we had a chance to talk about platelet management with many of the blood bankers at AABB. What they told us only validated what we learned in the survey – with patient safety always at the forefront, blood bankers need a better way to both (1) assure temperature compliance and (2) preserve precious platelet supplies. A temperature indicator would monitor platelet “temperature history” for the entire period it is out of blood bank control.

You’ve spoken and we’ve heard you

These recent interactions have revealed a potential new product need in the market. At Temptime, we have initiated the first steps of our new product development process focusing on a dual-range indicator for platelets. We are working to develop a deeper understanding of your needs and identifying potential product and technology solutions..

Get involved!

Temptime’s product development process depends on user input and field trials. If you’d be interested in providing input to the initial design and specifications for this new product development, we welcome your participation. Please email us and we will be in touch with you.

Survey Results

Q1: “Comments” Summary

  • 5-6 responses relative to time away from blood bank, lack of monitoring
  • 3 responses specific to agitation

Q1: “Other” Summary

  • 11 relative to time out of blood bank
  • 7 storage/uncontrolled environment
  • 7 spiked or modified bag/label
  • 5 “no swirling” observed
  • 4 noted “agitation” concerns

Q2: “Other” Summary:

  • 13 relative to time away and/or lack of monitoring/controlled environment (some specified >30 mins, > 2 hours)
  • 11 expired

Q3: Most common Text Responses summary:

  • 36 take temp with thermometer or temperature plate
  • 20 take temperature with IR thermometer
  • 16 “take temperature” (unknown how)
  • 13 use “touch/feel”
  • 7 report platelets returned in cooler, on ice or from fridge
  • 5 report that temp is monitored every 4 hours or constantly, or kept in temperature controlled chamber
  • 4 discard due to time

Q6: Most common Text Responses summary:

  • 6 report low usage or returns
  • 5 reference cost
  • 3 indicate would take temperature if unsure, indicator not needed 

Q8: Most common Text Responses summary:

  • 17 expired/outdated
  • 10 wrong/poor storage, including use of coolers
  • 7 time away from blood bank/control
  • 3 agitation concerns
  • 3 spiking bag and returned

Blood Bank Refrigerator Setpoints Matter

Learn about these important time/temperature correlations relative to your day-to-day blood bank operations.

Understanding the time pressures of busy blood banks, it would be fair to say that ANY time/temperature “advantages” – such as revisiting the refrigerator setpoint – might be worth consideration. Learn more in this VUEPOINT.

by Jeffrey Gutkind, Temptime

Over the past several months I’ve had the opportunity to visit some of the largest blood banks across the nation. In the course of talking with blood bankers about maintaining blood temperatures during storage, issue and transport, I observed a wide range of refrigeration setpoints, anywhere from 1.5oC to 4.7oC.

Reviewing my observations from these visits and reflecting on the AABB standard of 1.0oC to 6.0oC for storage, it brought me back to the “starting” temperature for blood when it’s removed from the refrigerator.

    • How does even a degree or two at a higher or lower storage temperature affect the blood temperature as it is dispensed and issued from the blood bank?
    • More importantly, how does the refrigerator setpoint affect how much TIME you have before the blood reaches 6oC?

To answer these questions, we asked Marielle Smith, Technical Service Scientist, to run a simple test in our lab.

How long does it take for refrigerated blood products to reach 6oC?

Blood Storage Temperature: 2°C vs. 4°C

The following table and graph show the time it takes for the core temperature of a refrigerated blood bag to warm to 6°C when removed from refrigerated conditions (2°C or 4°C) and placed on a counter-top at room temperature.1

The graph demonstrates that the lower the refrigerated storage temperature, the more time it takes for the blood bag to reach 6°C when warming at room temperature conditions. While these results are specific to the test method and setup used, they should be typical.

In terms of practical, day-to-day blood bank operations, what does this tell us?

Based on this test data, it suggests that blood bankers have over twice as much time to get blood issued and dispensed when the refrigerator setpoint is lower (2oC vs. 4oC). This represents a significant advantage for refrigerating blood at lower temperatures and longer times out of refrigeration before the blood goes out of specification.

Knowing that AABB guidelines state blood can be stored at 6oC for up to 42 days and transported between facilities below 10oC, and at the same time understanding the time pressures of busy blood banks, it would be fair to say that ANY time/temperature “advantages” such as revisiting the refrigerator setpoint might be worth consideration.

What do the blood refrigeration experts have to say?

After researching refrigerator setpoint specifications for a number of different vendors, we found that the factory setpoint is typically 4.0oC. Not being a refrigerator expert, I decided to reach out to Colleen Holtkamp Market Manager from Helmer® Scientific, to learn more. Colleen graciously provided these thorough answers to my questions, as well as thoughtful guidance for your consideration on setpoints, alarms and refrigerator specifications. (Colleen’s responses are in blue following the questions).

1. What is the typical factory setpoint temperature of your refrigerators when they go into the field? Are these setpoints easily changed, or does it have to be reset by the factory?

“The typical setpoint for Blood Bank Refrigerators is 4oC. Per AABB Standards, the acceptable temperature for storage of whole blood and most red cell components is 1oC to 6oC. Setting the temperature to 4ºC, close to the middle of the range, is standard practice for blood bank refrigeration.

It should be noted that the alarm setpoints are important, as well. AABB Standards state that alarms should be set to activate before blood components are exposed to unacceptable conditions. For example, since the lower limit for blood storage is 1oC, it makes sense to set the low alarm to 1.5oC (and since the upper limit is 6oC, a high alarm setting of 5.5oC is appropriate).

The ability to change the temperature setpoint depends on the manufacturer/brand of the refrigerator, as does the process for changing the alarm settings (instructions should be included in the refrigerator’s user manual).

Helmer Scientific Blood Bank Refrigerators enable the operating setpoint and alarm settings to be changed at the facility (they do not have to be reset by the factory). With temperature and alarm settings, it’s important to remember that while it should be reasonably convenient to modify them, it shouldn’t be so easy that they tend to be changed by mistake. A safeguard such as password protection for the refrigerator settings offers the best of both worlds – security and ease of use.”

2. Is there some type of statistic that you would use to say if the door is open for 3 minutes per hour; it will take XX minutes to get back down to the original setpoint?
As an example: If the refrigerator is set to 3.0oC and the door is open for 2 minutes, how long will it take for the refrigerator to get back down to the 3.0oC setpoint?

“There isn’t a standard method for measuring temperature recovery after a door opening. It can be impacted by variables such as ambient temperature and how much cold product is stored in the refrigerator at the time. What is important is that the unit has a heavy-duty, forced air refrigeration system and that the fan stops running while the door is open so that it does not blow out the cold air. In addition, the refrigeration system should be powerful enough to circulate the air inside the cabinet multiple times shortly after the door is closed, ensuring quick temperature recovery.

Another consideration is the importance of alarms. Having both a door open alarm and a high temperature alarm provides two layers of protection against temperature excursions due to door openings.”

3. What is the typical tolerance for blood bank refrigerators? (we found this information difficult to find in our online research).

“Blood Bank requires the tightest temperature uniformity of any cold storage application. The typical temperature uniformity specification for Blood Bank Refrigerators is +/-1oC. While not necessarily a regulatory requirement, many Blood Banks have written this specification into their internal protocols/SOPs. Therefore, it has become a community standard that drives performance expectations for Blood Bank Refrigerators.

Before a Blood Bank considers changing refrigerator setpoints from 4oC to 2oC, it is critical to think about the following information. If a blood refrigerator is set to 2oC, with uniformity of +/-1oC, the temperature inside the unit might reach the lower limit of the acceptable range (1oC). Also, if the low alarm is set to 1.5oC (which is advisable because AABB standards state that alarms should activate before blood is exposed to unacceptable conditions), it may be triggered by operation at 2oC. Helmer Scientific’s priority is to optimize the temperature of the blood bag while it is stored in our units. The setpoints and alarms are established to protect the blood while it is in the refrigerator.”

When it comes to blood bank refrigeration setpoints, what have we learned?

• The typical factory setpoint for blood bank refrigerators when delivered from the manufacturer is 4.0oC
• The ability to change the refrigerator setpoint at the blood bank varies by manufacturer
• Blood that is stored at 2oC takes over twice as long (approximate, based on our test) to reach 6oC at ambient, when compared to blood stored at 4oC
• Temperature recovery of refrigerators is affected by a number of variables (door opening, amount of stored cold product, ambient operating temperature)
• Low and high alarms, as well as open door alarms, are important and recommended by the manufacturers

If you have any recommendations, experiences, questions or ideas relative to refrigerator storage temperatures and your blood bank, we’d love to hear from you. Please POST A COMMENT or email us.

Jeffrey Gutkind
jeffg@temptimecorp.com

1Test Details
At each storage temperature, a total of six (6) simulated blood bags were tested. Each 600mL PVC blood bag (Charter Medical) was filled with 350mL of a mixture of 10% glycerol and 90% water, to simulate red blood cell volume. The bags were removed from refrigerated storage (at 2°C and 4°C) and then placed lying flat on a counter-top at room temperature (at approximately 21°C with 30% R.H). The temperature was measured by placing a calibrated temperature-sensing probe in the center of the simulated blood mixture inside the bag and the temperature was monitored using a calibrated Oakton Thermistor Thermometer. Temperature readings were recorded at 1 minute intervals. The data represents the time needed for the simulated blood mixture (10% glycerol with 90% water) to warm to 6°C.

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