Keeping Blood Products Cold During Dispensing

Tests show that gel blankets significantly help maintain temps below 6oC

Test Blood Bag Warming using reusable ice packsOn a recent visit to a blood bank customer who uses Safe-T-Vue 6, we learned something that we felt was worth sharing. During the approximate 10 minutes that it often took to do paperwork and cross-matching, they sometimes experienced the Safe-T-Vue 6 (STV-6) “tripping.” This caused concern that the blood product may have been compromised by room temperature exposure, even for a seemingly short time period.

To address this problem, they began using refrigerated gel blankets (reusable ice pack sheets) to keep the blood product cool. Taking this simple step of placing the blanket around the blood bag(s) during preparation and before transport to the ER/OR has given them confidence that the blood product has been kept cool, and the STV-6 provides visual indication and reassurance that 6°C has not been exceeded.

Wanting to learn just how much the gel blanket helped, we turned to Marielle Smith, Technical Service Scientist in our Temptime Lab, to do some testing. You may be surprised by what we learned.

Read this VUEPOINT to see the test procedure and learn from the detailed data we gathered. It may inspire you to try gel blankets in your blood bank!

Tests to compare blood bag warming with and without refrigerated gel blankets

When blood banks are preparing refrigerated blood bags for transport to the OR/ER, there is limited time for blood bank personnel to record the necessary patient information (cross-check, paperwork, etc.) before the blood approaches critical temperatures. Many blood banks use Safe-T-Vue 6 for exactly this reason.

Previous studies have shown that bags warm quickly to temperatures (6.0°C in less than 10 minutes) rendering the blood unsuitable for use. Results from this new study, however, demonstrate that using a refrigerated gel blanket (such as the Thermafreeze Reusable Ice Pack Sheet) makes a significant difference in slowing the warming rate when the blood product is removed from refrigeration to typical room temperature conditions.

Test procedure setup

A test was performed to assess whether using a refrigerated gel blanket can add to the longevity of the blood bags upon removal from refrigerated storage (1°C – 4°C).

The test was setup to collect temperature data as follows:

1. Control, single bag with no gel blanket
2. Single bag with small gel blanket, cutout window (to view Safe-T-Vue 6)
3. Three bags with larger gel blanket

Six (6) bags of 350 mL simulated red blood cells volume were used for scenarios 1 and 2, and 18 bags were used for scenario 3.

Reusable Ice Pack Sheets (e.g., gel blanket) were obtained and cut into different dimensions to allow for testing either a single bag (with a window cut-out to view the Safe-T-Vue 6 indicator) or 3 bags side-by-side.

Small gel blanket with viewing window for 1 bag

Large gel blanket for 3 bags

Temperature measurement

Calibrated temperature probes were inserted into each of the simulated blood bags. Calibrated electronic thermometers (accuracy of at least ±0.1°C) were used to record the temperature of the fluid inside the filled blood bags.

After pre-conditioning in the refrigerator (maintained between 1°C to 4°C) for at least 24 hours, the bags and the gel blankets were removed and placed lying flat on a counter-top at room temperature conditions (19°C ± 1°C with 50% R.H). A timer was set to count-up mode and temperature readings were recorded at one minute intervals until the temperature inside the bag reached 6°C.

Test results

The data points on the graph below show the gradual warming of the bags as the refrigerated blood bags warm to 6.0°C in room temperature conditions when the blood bag is either wrapped in a refrigerated gel blanket, or left as is upon removal from refrigerated storage (control).


  • Without using a gel blanket, blood bags warmed from 3.2°C to 6.0°C in approximately 9 minutes
  • Using a small gel blanket (with a window cut out to allow for visual interpretation of the Safe-T-Vue 6 indicator), blood bags warmed to 6.0°C in approximately 25 minutes
  • Using a large gel blanket for testing up to 3 bags side-by-side, blood bags warmed to 6.0°C in approximately 32 minutes

Conclusions and recommendations

The results presented in this report support that a pre-conditioned refrigerated gel blanket can be wrapped around blood products to keep the blood below 6°C for an extended period of time – while blood bank personnel are preparing the blood for transport to the ER/OR.

When a simulated blood bag was wrapped in a refrigerated gel blanket upon removal from refrigerated storage (1°C to 4°C), the bag warmed to 6.0°C within about 25 to 32 minutes on a counter at room temperature conditions. As an added precaution, a Safe-T-Vue 6 indicator can be used to provide irreversible visual indication of temperature excursions beyond 6.0°C.

Order free samples of Safe-T-Vue 6

Cooler Validation: Comparison of “Manual” Thermometer vs. “Automated” Data Logger Methods

In our March 2012 survey of over 70 blood banks, many respondents generally described cooler validation as a “pain,” characterizing it as time-consuming, frustrating and even primitive.

Most blood banks revalidate their transport coolers annually. And although it is only once a year, there never seems to be a good time or resource-efficient way to do it.

Using multiple data loggers allows more accurate temperature mapping of the cooler interior.

The three key factors we hear repeated most often are:
1. Time Efficiency (technician’s time)
2. Data Accuracy
3. Simplifying Documentation

At the SCABB/CBBS meeting last month, we entertained compelling discussions with blood bankers who have switched from manual cooler validations with thermometers, to using data loggers (electronic temperature recorders). Some of them are using the Val-A-SureTM Cooler Validation Kit.

If you’ve ever considered switching to an automated validation process, we thought it might be helpful to share what we’ve learned from blood bankers across the country. In the following table (next page) we compare the traditional “manual” thermometer method to the “automated” data logger method – and capture how it has changed their validation experiences.

This graph displays temperature of the top bag vs. the bottom bag. The data is downloaded from data loggers and printed for permanent validation documentation, eliminating handwritten and transcribed data.

We’ll be giving away a Val-A-Sure Cooler Validation Kit at AABB 2015, so if you’re interested in a “free” chance to change your cooler validation method, be sure to stop by and see us!

Jeffrey Gutkind

P.S. For more on Transport and Storage Coolers, check out our Tips, Helpful Ideas and AABB Standards References on

COMZ VUEPOINT – Cooler Validation-Comparison of Manual Thermometer vs. Automated Data Logger Methods – web version (doc. 2341)

Are all temperature indicators created equal?

When it comes to cost and performance, how do you choose?

by Jeffrey Gutkind

In today’s cost-conscious healthcare environment, our immediate reaction when making a buying decision is to minimize purchase cost.   The temperature indicators currently on the market have different costs.  And there are questions you may be asking:

  • is the “cheapest” purchase price going to save the blood bank money overall?
  • are all indicators equal in terms of performance?
  • how do you know which indicator to choose?

To answer these questions, let’s take a step back and question WHY we even use temperature indicators.

Temperature indicators for blood products were originally designed to provide assurance that blood product temperatures had not exceeded AABB temperature guidelines when the blood is out of the blood bank’s control. The temperature indicator provides proof that the blood product has been maintained at proper temperature while out of the blood bank control.

Numerous visitors to our AABB booth a few weeks ago stated that 40-50% of the blood issued from their blood banks is not used. To further illustrate the challenge, a journal article recently published in Transfusion (shared in our August 2014 VUEPOINT), described a study by a blood bank that stated how most of their blood waste was from either temperature or time (away from the blood bank) excursions, and that 70% of those losses came from blood products issued to the OR in coolers.  Temperature indicators are used by blood banks worldwide for exactly this reason – to provide assurance that the blood products at no time exceeded temperature thresholds, to help maintain blood product quality and to minimize blood waste.

So, other than cost, what matters when choosing an indicator?

Let’s circle back to our initial questions of the temperature indicator cost and the temperature indicator performance.  Since the job of a temperature indicator is to provide temperature information back to the blood bank, the indicator’s temperature ACCURACY (also referred to as “tolerance”) is critical.

As an example, of the three most popular 10o C temperature indicators on the market today, each publishes a different accuracy specification:

  • Safe-T-Vue 10  +/- 0.4 o C
  • Indicator A +/- 0.5 o C
  • Indicator B +/- 1.0 o C

How does indicator accuracy influence blood product waste?

In this illustration, you can see that a 10oC indicator with an accuracy of  +/- 1.0 may actually “trip” at 9 o C, thus falsely indicating that the temperature of the blood is out of specification.  And, as we all know, the cost of wasted blood itself far exceeds the purchase price of an indicator – and minimizing blood waste (not indicator cost) is the primary objective behind using a temperature indicator.

Using an average cost of $250.00 for a single wasted blood unit, it’s easy to calculate the potential savings of using a more accurate temperature indicator.   The cost difference in temperature indicators is minimal in comparison to the cost of one wasted unit of blood.

When comparing temperature indicators to make a buying decision, be sure to make ACCURACY comparison a key factor in your selection process.  Safe-T-Vue indicators are available in 6°C and 10°C temperature indications, both accurate within +/-0.4°C.  *

As always, we welcome your comments and feedback on the ideas presented in this VUEPOINT.


Jeffrey Gutkind

* Refer to AABB standards for blood banks and transfusion services, 21 CFR 640.2, 21 CFR 640.4, and 21 CFR 600.15.

How can you monitor CORE blood bag temperature with adhesive temperature indicators?

With several indicators on the market, it’s increasingly confusing to know what to use – or who to trust.

There’s been a lot of “buzz” lately about measuring core temperature of blood units during temporary storage and transport.  Do the adhesive temperature indicators on the market, including Safe-T-Vue, measure core temperature?

The simple answer is NO.

Since all of the available temperature indicators are applied to the blood bag surface, they do not measure core temperature. As most of you know, there is no way to measure core temperature of a blood unit during temporary storage and transport without inserting a temperature probe into the “core” of the bag.

So, if the indicators aren’t sensing core temperature, what are they sensing?

These adhesive temperature indicators are actually measuring the surface temperature of the bag, not core temperature.  Safe-T-Vue also measures the surface temperature of the bag. However, through over 20,000 laboratory tests, we have developed direct correlations between blood bag surface temperature and core blood product temperatures.  This process allows us to formulate a consistently performing adhesive surface indicator, and assures that Safe-T-Vue indicator response is accurately correlated to actual core temperatures.

How can you trust the performance of a temperature indicator?

1. Published product specifications

Suppliers, like William Labs, publish the temperature accuracy of their products, usually in their product literature and on their websites.

Safe-T-Vue has correlated temperature indication to core blood bag temperature supported by over 20,000 test data results that quantitatively support the consistency, predictability and repeatability of its indicator performance.

2. QA Documentation

Some suppliers take the “proof” of temperature accuracy a step farther, by supplying their customers with QA documents and procedures, documenting the temperature data for that product, for each lot, to prove that testing was performed and the product performs to specification.  Safe-T-Vue is shipped with accompanying QA documents, which can also be accessed anytime from our website.

For added confidence and convenience, the validation procedures for Safe-T-Vue are published on the website, for those users who would like to perform their validations and replicate our work in their own labs.

3. FDA 510(k) and Quality Audits

As you know, the purpose of the FDA is to oversee safety.  Section 510(k) helps the FDA make sure new medical devices are safe and effective. New medical devices submitted under 510(k) rules must also be “substantially equivalent” to other similar marketed products.

This FDA regulation that applies to medical devices, including temperature indicators, is of critical importance.  It assures that the supplier of the product you are trusting to “do its job” is both safe and effective.  510(k) ensures the product is as safe and as effective as other 510(k) devices already on the market.

Just because a product is being sold into the healthcare market, do not assume it has been cleared by FDA 510(k).  Ask your supplier – and make them prove it.

Additionally, credible suppliers have a quality plan to support the process and accuracy claims of their products.  For example, actual and statistical verification of Safe-T-Vue data supports the product claims.  As part of the quality plan, this data is reviewed by the company’s QC staff and annually by external auditors.

What’s next?

We’ve been so stimulated by the recent conversation about core temperature, that we’re making plans now for comparative studies in early 2014, which we will be sharing with you.  Our new partnership with Temptime has expanded our time-temperature testing capabilities and laboratory expertise in healthcare, so look forward to these and other test results in the coming year.

As always, if you have any thoughts on core temperature measurement and adhesive temperature indicators, we always appreciate hearing from you.  Feel free to post a comment on the VUEPOINT post, or email us.