Several members have asked questions about blood warmers:

1. One member wanted to know how transfusion services monitor blood warmer use. According to the AABB Standards (20th ed.) state under 3.5.2 "When blood or components are warmed, warming shall be done so as to not cause hemolysis." The member wants to know how others document compliance; do you require documentation of blood warmer temperatures with each use? If so, do you document a single temperature reading at the outset of transfusion or do you record serial temperatures? Do you require documentation of the serial number of the warmer used? Do you document in the patient's chart or in a separate log and do you keep records on file in the Transfusion Service? The inquiring member is currently documenting preventive maintenance but relies on anesthesia records for documentation of warmer use and temperatures. His hospital does NOT require documentation of blood warmer serial numbers. In response to the above question, the following was submitted by a blood bank physician at a large teaching hospital in Los Angeles. The responding member states that her institution has centralized the maintenance of blood warmers. Biomedical Engineering is responsible for making sure all blood warming devices function according to the manufacturer's specifications. Biomed engineering gives a report on the blood warmers on a quarterly basis at the Transfusion Committee. About four years ago this member's institution was cited for not having documentation of maintenance for many blood warmers. Since centralizing the maintenance, the compliance with blood warmer maintenance documentation has been 100%. The equipment is checked for physical condition, such as cracks, filters, leaks, alarm, and indicator etc., and for electrical safety. A functional check is also performed to make sure that operating water temp is between 41 C and 42 C (temperature specification varies with the manufacturer) to allow for a certain amount of heat loss to occur as the blood flows out of the warmer and into the patient. The specifications for one of the blood warmers includes that the "over temperature" alarm is set at 44.9 C.

2. A second member wants to know if any one has experience with the use of a blood warming system called the "hotline" for exchange transfusion in newborns? No members provided any input to this question.

3. A third member has asked for advice regarding the Ranger Blood/Fluid Warming System. The inquiring member's hospital is considering purchasing this blood warming system. If purchased, the inquiring member indicates that the blood warmer would be used for the apheresis cell separator's extra corporeal circuit. The Ranger Blood/Fluid Warming System distributes an "AABB Fact Sheet" to support its specifications for a 41 C set point for the operating temperature. However, the following alarm set points are built into the operations of this device: Over temperature primary set point = 43 C; Over temperature secondary set point = 46 C; Under temperature set = 33 C. The inquiring member asks if anyone is using this warmer, and if so, "why would a manufacturer design a warmer that operates at a non-physiological temperature and so close to the safety edge?" No member provided input.

4. A fourth member wants to know what is the experience of the blood banking community, with respect to the maximum temperature that is safe for blood to be warmed, before there is risk of damage and shortened red cell survival? Again, no member gave input to this question.

5. A fifth member commented that at her institution, for each therapeutic or research apheresis procedure, once the blood warmer has achieved its optimum temperature, this observation is recorded on a procedural flow sheet. The assigned number and manufacturer of the blood warmer is also documented on the flow sheet. The member states that they are not requiring documentation of the serial numbers of each blood warmer. These become permanent records and are kept in the patient or donor's chart at the blood center.

6. Finally, the EDITOR suggests that you read a recent guidance document that represents the FDA's current thinking on the review of premarket notification submissions for blood and plasma warmers used in blood establishments.

ADDENDUM Aug. 24, 2001

7. A member commented that at her hospital they implemented a centralized system for maintenance of blood warmers. Under this system, their Biomedical Engineering Department is responsible for assuring that all blood warming devices function according to the manufacturer's specifications Biomedical engineering gives a report on the blood warmers on a quarterly basis at the Transfusion Committee. About four years ago this facility was cited for not having documentation of maintenance for many blood warmers. Since centralizing the maintenance of the blood warmers, their compliance has been 100%. The equipment is checked for physical condition, such as cracks, filters, leaks, alarm, and indicator etc., and for electrical safety. A functional check is also performed to make sure that operating water temperatures are between 41C and 42C (the temperature specification varies with the manufacturer) to allow a certain amount of heat loss to occur as the blood flows out of the warmer and into the patient. The specifications for one of the blood warmers (the rapid infuser) calls for the over temperature alarm to be set at 44.9C.

Please send further questions and comments (in particular, for the unanswered questions posed in questions #2 to #4 above) to the address below.

ADDENDUM Dec. 24, 2003

8. Editor's Note: Another aspect of this issue has just been posted.

Please submit comments to the e-Network Forum.

Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator