A woman checks a Safe-T-Vue sensor on a blood bag
By Chris Caulfield | February 02, 2022

Busy Blood Banks Need More Assurance That Blood Products are Viable Before Transfusions. This Might Help.

Thousands of blood banks are starting to rely on irreversible temperature indicators to confirm blood products have not become too warm during refrigeration, storage and transport.

Some say the pandemic is the public health crisis of our generation. But if you ask blood banks, they might disagree.

Just hours before I sat down to write this, the American Red Cross declared its first ever national blood crisis. The U.S. is currently experiencing the worst blood shortage in a decade, with dangerously low inventory levels attributed to multiple factors. Ongoing blood and plasma shortages in Europe, Africa and other regions also have regulatory bodies working with non-government organizations and the healthcare community to consider new directives and practices that can reduce or prevent an equal crisis.

Preserving every blood donation has become a global priority.

As such, many blood banks are turning to technology-monitoring tools to ensure units being distributed to hospitals and ambulatory surgery centers remain consistently below the prescribed temperature limit (usually 6°C or 10°C) and can be administered to the patient. Interestingly, though, some organizations are going a step further and leveraging these irreversible temperature indicators for reverse logistics. They are required to confirm unused units returned to the blood bank have not exceeded temperature thresholds – as defined by AABB Standards and 21 CFR 640 – and allowing them to make an informed redistribution decision.

Experts Say the “30-Minute Rule” Can’t Always be Trusted

All blood banks have a responsibility to ensure donated blood and blood products are safe before they are used. Extensive lab testing is conducted to identify certain proteins or infectious disease pathogens are not present when donated blood is accepted into the blood bank system.  Once it is processed and made available for use, the primary hazard for the blood is heat exposure during storage or transportation that can negatively impact patient outcomes during blood transfusions. Despite this risk, many organizations still rely on the “30-minute rule” to monitor cold chain performance and confirm blood product viability.

However, many clinicians, researchers and others in the healthcare community have questioned the reliability of this “test” method in recent years.

As one published paper notes, “The quality of [red blood cells] RBCs depends on the storage conditions. The 30-minute rule could be shortened or lengthened if the acceptable temperature threshold is breached or maintained. The unknown factor is that one cannot confirm that the cold chain (system used to prevent biologic entities from deterioration by exposure to unacceptable temperatures) was maintained.”

In turn, we have received many calls from laboratories and blood banks that want to put the 30-minute rule to the test in their own facilities and supply chains using Zebra’s Safe-T-Vue® 10, manufactured by Temptime. Safe-T-Vue is an irreversible temperature indicator that provides an easy-to-read visual cue if a blood product has reached or exceeded the indication temperature to support compliance with blood handling requirements.

What customers have since confirmed is that the rule may work for smaller blood banks supporting just a few transfusions, but it generally cannot be trusted as “truth” in more fast-paced hospitals where blood is issued to the operating room (OR), emergency department or individual floors. With the units typically transported in coolers, blood banks, hospital workers and others involved in the logistics process cannot be confident the returned blood units have been kept at the appropriate temperature. As such, blood banks can’t re-inventory those units for re-issue, so they must dispose of them.

This is the fundamental problem with the “30-minute rule.” It does not provide the verification that the blood has been kept below the required temperature during the entire time it has been outside the blood bank. This leads to unnecessary waste of blood because those units may have remained in the proper temperature range the whole time and could have been restocked for future use.  Though waste is never ideal, these are live-saving blood products we’re talking about.

We’re Far Beyond Proof of Concept

As I mentioned, blood banks, labs, hospitals and others in the blood products supply chain contact us when they are seeking a trusted technology to assure that every unit is being properly handled from a temperature perspective. They have heard about the blood temperature indicators and want to see if they meet the performance requirements and can provide the level of confidence needed in the maintenance of the cold chain – adding a new level of trust in both their shipping and return receipt processes, as well as blood product prep ahead of transfusions.

Rightfully so, many organizations want to test the Safe-T-Vue technology for themselves in their real-world environment versus relying solely on references. I remember one customer in particular that conducted a performance qualification and comparison study of two different types of blood temperature indicators with the goal of evaluating which would best meet its needs. It supported multiple blood banks of varying sizes and wanted to ensure it was using a product that would be right for all.

The customer ultimately chose Zebra’s Safe-T-Vue® 10 because it was simpler to interpret temperature excursions and was more accurate. That’s because with the Safe-T-Vue, as the blood bag begins to warm up, the indicator goes from white to red speckled to fully red. It’s very clear and easy to read.

Once the organization settled on the Safe-T-Vue indicator, though, it decided to take its research a step further with a comprehensive qualification study to verify it would work across several scenarios. To do that, its team simulated real blood bags by using a mixture of water and 10% glycerin. The team tested different volumes of bags and put the Safe-T-Vue on different areas of the bag. It used NISD probes to monitor internal temperatures and to compare how the indicator reacted.

Not surprisingly (at least to us), the customer’s findings showed that regardless of where Safe-T-Vue indicators were placed or volume of the blood bags, the results were the same. In all instances, the color of the indicator began to turn speckled at around 9º or 9.5ºC and were fully red at 10ºC. The team also conducted subsequent qualification studies with similar findings. Four years later, it tested Safe-T-Vue indicators on thawed frozen plasma and then, four years after that, on low titer whole blood.

Minimized Risk of Wasting Valuable Blood Supplies, Including Plasma

The primary reason for using blood temperature indicators, of course, is to prevent heat exposure blood products from being used, reduce blood product waste, and preserve blood products. It’s estimated that RBCs cost about $350 per bag, not including the labor involved for bringing it into inventory, which also adds to the overall expense. With Safe-T-Vue, there’s no question as to whether the blood product has stayed below 10ºC – eliminating the risk of disposing of units that are still viable because of any temperature control uncertainty.

This particular organization found that using the Safe-T-Vue for five-day plasma also saves critical time. It takes about 30 minutes to thaw plasma, which is done in a water bath as bags are agitated. Once thawed, the plasma is put in the refrigerator to cool, then a Safe-T-Vue is applied to the bag so it’s ready to dispense. That means plasma is always on hand, and there is no need to take the time to thaw it and then cool it to the appropriate temperature at the time it’s needed.

This is important considering that nearly 5,000 units of platelets and 6,500 units of plasma are needed daily in the U.S. alone, according to the latest American Red Cross estimations.

The Risk of Following “the 30-Minute Rule”

When it comes to blood products, extreme care must be given to make informed decisions. Even if we weren’t facing a blood or plasma crisis, we wouldn’t want to lose even a single unit due to subjective decision-making. Yet, this is a likely scenario if we leave it up to “time” to tell us whether a blood product is inside or outside an acceptable temperature range. That is why U.S. regulation does not include "time" as an appropriate single characteristic to determine whether a unit could be restored back into inventory and continual “temperature” measurement has become the standard.  

In other words, no one should be making a life-changing call based on the 30-minute rule.


Editor’s Note:

You can learn more about the Safe-T-Vue and how it can help you better monitor and manage your blood products here.

I also recommend you check out this infographic.

Healthcare, Best Practices,
Chris Caulfield
Chris Caulfield

Chris Caulfield is the Vice President, Temptime Operations. He oversees all aspects of the Temptime operations in Morris Plains, NJ.  Chris joined Temptime Corporation in 2000 and most recently served as Vice President, Global Customer Development where he worked directly with Temptime’s global pharmaceutical and vaccine manufacturing customers, global health agencies, and ministries of health. Chris earned a B.A in Economics, as well as a minor in political science, from Villanova University (Villanova, PA).

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