Monitoring FFP for inadvertent thawing and refreezing

A California blood banker asks if it is a requirement or merely a recommendation to monitor FFP for inadvertent thawing then refreezing by using an indicator system such as rubber banding the bag of plasma before it is first frozen or checking the product for a change in bubble positioning. The California blood banker points out that if we are required to monitor storage temperatures of FFP and to maintain the product in a frozen state, why is that monitoring not sufficient? Do we really need to look for displaced bubbles or altered indentations?

Before sharing the above questions with the full e-Network Forum, this question was reviewed by a North Carolina physician familiar with the development of the AABB Technical Manual and the AABB Standards. The North Carolina blood banker reports that the AABB Standards do not specifically address the use of an indicator system such as rubber banding the bag of plasma before it is first frozen or checking the product for a change in bubble positioning, but that in the 13th edition of the AABB Technical Manual it states "FFP should be frozen in a manner that makes it easy to detect inadvertent thawing and refreezing". Three simple methods of accomplishing this are given (tube indentation, bubble position or rubber band indentation). The North Carolina blood banker adds that since FFP is frequently transported both between institutions and within an institution, it is possible that for periods of time the FFP is not in a completely controlled monitored environment. Thus, in the reviewing blood banker's opinion it would seem prudent to adhere to the relatively simple advice (recommendation, not requirement) of the AABB Technical Manual to assure optimal storage. Alternatively, in the case of power outage or mechanical failure, such a precaution may allow one to assess the adequacy of storage after the problem is addressed.

Editor's note: The introduction to the AABB Technical Manual reminds us that the AABB makes efforts to have its various publications consistent in regard to acceptable practices. However, for several reasons, these publications may not always be in perfect harmony. Quoting from the Technical Manual "First, as new developments in the practice of blood banking occur, changes may be recommended to the Standards for Blood Banks and Transfusion Services. It is not possible, however, to revise each publication at the time such a change is adopted. Thus, it is essential that the most recent edition of the Standards be consulted as a reference in regard to current acceptable practices. Second, the views expressed in this publication (the Technical Manual) represent the opinions of authors. The publication of this book does not constitute an endorsement by the AABB of any view expressed herein, and the AABB expressly disclaims any liability arising from any inaccuracy or misstatement."

The e-Network Forum is encouraged to comment on the use of methods to monitor for inadvertent FFP thawing/refreezing, including tube indentation, bubble position or rubber band indentation. In addition, it would be interesting to know if any e-Network members or their institutions rely on the AABB Technical Manual as a 'standards' setting document, and if so, why?

The following responses have been received.

1. A blood banker who used to work at a major teaching hospital in Los Angeles says that at his previous place of employment, they monitor for inadvertent thaw/refreeze of FFP by using an indicator system consisting of a test tube containing cake coloring dyes that have been dissolved in water and frozen in layers. If the colored ice within the test tube thaws, the layered coloring is lost. This indicator system is useful where an alarm system fails to indicate a lack of power (a problem with some older plasma freezers) or while FFP is in a transport cooler. The indicator tubes are prepared by mixing coloring agents (this particular blood bank uses blue and gold) with water. They take one of the colored solutions and pour it into plastic tubes and freeze them. After being frozen solid, a few drops of plain water are added to create an interface. The tubes are frozen again, and then the second color is added on top of the interface. The tubes are capped and frozen again. In the end, the laboratory has indicator tubes containing layered blue and gold colored ice with a clear interface. If the indicator tube is thawed, the colors mix and if re-frozen, the sharp blue/gold color separation is lost, and a combo color is seen. The tubes do not need to be held upright and are placed next to the internal thermometers. The color indicator tubes are viewed each AM when the charts and temperatures are checked. The responding blood banker suggested that at the Editor's institution, cardinal and gold colors could be substituted for blue and gold!

ADDENDA Feb. 21, 2002

2. A blood banker from the United Kingdom (UK) is of the opinion that in England FFP is not monitored by use of an indicator system, as suggested by the AABB Technical Manual. Rather the UK recommendation is that all refrigerators and freezers containing blood products for clinical use are controlled with temperature recorders and alarms which are set off if the storage device goes out of the pre-determined temperature range. If the refrigerator/freezer goes out of temperature control, products are moved to another site and if necessary to the nearest Blood Centre.
   
   
3. A blood banker from the Northeastern USA asks "isn't this a bit of overkill? If the units are in a monitored freezer that documents maintenance of appropriate temps, when is the thawing going to occur?"
   
   
4. A blood banker in Michigan wrote that while the freeze/thaw indicator used at the major teaching hospital in Los Angeles seems like a fun solution (no pun intended), the Michigan blood banker thinks that this is overkill, if the freezing device in question has an alarm with battery back up and a recording chart. She adds that when they made products themselves, they put a rubber band on the unit so that it had a crimp in the bags. Once frozen, they cut the rubber band. There are probably a number of reasons blood centers do not want to do this today. The unit was the indicator, rather than using an indicator for the freezer.

ADDENDA Feb. 24, 2002

5. A blood banker from a 'New England Medical Center' in Boston wrote the following opinion, which is in contrast to the advice written in the current Technical Manual. "The AABB's recommendation on monitoring FFP inadvetent thawing and refreezing has been a bone of contention with me. Over the years the Technical Manual Committee has weeded the book of what was once described to me by an AABB director as "blood bank chestnuts". There was a time when the Manual was filled with these prudent recommendations; most were removed years ago, but this one has remained for too long. A long time ago in a galaxy far away I conducted an experiment to disprove a blood bank chestnut, one that involved making platelet concentrates only from whole blood that had been drawn in 8 minutes or less. Now I can hear the cries or "WHAT?!!" from the younger crowd but it was assumed that fast, free flowing blood would be richer in platelets than a slower, stagnant flow. A prudent thought, you might think. A number of technologist school projects (including my own) and a few larger, more formal studies proved otherwise. The 'chestnut' disappeared from the Manual with the next edition. Colored Water, air bubbles and indentations are all fraught with good intentions, but I am forced to pose the question, Is this really necessary? In the present environment, even smaller hospital blood banks have continuously monitored refrigerators and freezers with alarm systems that by AABB standards are subjected to a quality control program. In many cases remote alarm systems are in place, allowing monitoring of storage units outside the bank's proximity or for security personnel to respond. An increasing number of institutions (even small ones) are installing centralized monitoring systems. And nearly all have their storage units hooked up to emergency power. Given these circumstances, It strikes me that to monitor an air bubble or the indentation in a unit a shockingly crude way to determine whether or not your freezer has failed. I seriously doubt any medical director would order the destruction of a freezer full of plasma on the sole evidence of a color water detector. Whatever happened to checking the recording chart daily? With regard to transport, an argument might be made for including a color water device, but only in the situation where a package is delivered, not inspected immediately, and thrown in a walk-in freezer. But for simple transport, I think it unnecessary. the Standards committee has seen not to address this. Prudently. In short, this concept is a holdover from the Elder Days of blood banking (of which, I must confess, I was a part of) a time when the layers of redundancy were considerably less. I look forward to the day when the Technical Manual Committee will retire this 'chestnut', archive it in the appropriate historical bin (where it can be properly catalogued and readily accessed, of course) and remembered with fondness by aging blood bankers like myself." The author of this quote adds that he would be pleased to address any responses that might be directed to him, if there are any.

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