Turner: Evaluation of the efficacy of thawing canine fresh frozen plasma using a microwave plasma defroster
Transfusions are often given in veterinary medicine in cases of severe, life-threatening blood loss, trauma, and clotting dysfunction. Clotting dysfunction, or coagulopathy, is often caused by reduced levels or absence of blood-clotting proteins, known as clotting factors. Canine fresh frozen plasma (FFP) is the preferred transfusion product to replace deficient clotting factors in these clinical situations. Canine FFP is prepared by blood banks by separating whole blood into two separate fractions: red blood cells (becoming packed red blood cells) and plasma. Immediately freezing the plasma fraction allows for preservation all of its beneficial proteins, including labile factors that can degrade over time. Fresh Frozen Plasma can be shipped, stored and used by veterinarians for up to one year as long as it remains frozen until needed and thawed immediately prior to use.
Storing plasma in the frozen state extends its shelf life for storage and facilitates shipment, but presents a serious obstacle when animals with life-threatening emergencies require immediate transfusion. Currently, the standard practice for thawing canine FFP is to defrost the product in a warm water bath. This method has been reported in human and veterinary studies to take between 17 and 35 minutes. Prolonged thaw times of up to 70 minutes have been experienced anecdotally at the authors’ institution. This is an unacceptable lag in treatment that can result in patients deteriorating or even dying while waiting for transfusions. To reduce the delay of plasma transfusions in human medicine, various microwave defrosters were developed. This technology has been shown to be an effective and fast method of thawing human FFP.1–8 Many human hospitals have implemented microwave plasma defrosters in order to decrease total defrost time (as low as 5 minutes), thereby decreasing time to life-saving transfusions. Although this technology has proved to be useful in human medicine, no studies have evaluated the use of this potentially life-saving technology for canine patients using a purpose-built microwave plasma defroster. A single study in the veterinary literature attempted to modify a kitchen microwave oven for transfusion use, but were unable to produce a clinically useful product.35
This study attempts to prove that a purpose-built microwave plasma defroster will be a time-effective method of thawing canine FFP resulting in a thawed plasma that is clinically useful. Determination of clinical utility is verification that clotting proteins/factors were preserved in the thaw process. The canine FFP units for the study will be donated from excess stock by the Blue Ridge Veterinary Blood Bank (a member of the American Association of Blood Banks). This blood bank is comprised of 100% volunteer donor animals that belong to families not associated with the blood bank. Animals are not housed on site, not sedated for donations, and are assessed for willingness to cooperate prior to donation. Animals unwilling to cooperate are not used for donation.
Units of plasma will be thawed via plasma microwave defroster per manufacturer instructions. Time to thaw will be recorded and final thawed temperature will be registered using both surface and immersion thermometers. Plasma defrosted in the microwave plasma defroster will be sent to a comparative coagulation laboratory for evaluation of coagulation tests (clotting times and clotting proteins/factors). These values will be compared to the laboratory's normal values. Units with values within the laboratory’s reference ranges will be considered adequate for clinical use.
If the author’s hypothesis is proven, this study will provide the foundation for this life-saving technology to be introduced into veterinary medicine.