From detective protocols to chronic transfusions; a behind-the-scenes look at the laboratory’s role in clinical outcomes for transfusion patients
Vol. 24 • Issue 10 • Page 12
The transfusion process is a shockingly common medical procedure – especially considering the complexity of the work involved. For clinicians and physicians alike, the pressure is on and the risks to the patient can be high, which is why the role of blood banking laboratories is so vital. In a recent interview with ADVANCE, Lynne Uhl, MD, chief of the division of laboratory medicine at Beth Israel Deaconess Medical Center, associate professor of pathology at Harvard Medical School and president of the board of directors at AABB, took a look at the possible obstacles and complications of performing a transfusion.
Typically, patient transfusions go relatively smoothly, leading to positive outcomes with little-to-no adverse reactions, but that doesn’t mean complications don’t exist. An adverse reaction can be either infectious or non-infectious. Both reactions can range from mild to severe to anything in-between, depending on the circumstances of the transfusion. Infectious complications like the transmission of HIV, HCV or even Hepatitis B are extremely rare and usually weeded out during the donor screening process, but non-infectious reactions can come from any number of circumstances. On the more severe side of transfusion medicine, patients can have hemolytic transfusion reactions, transfusion-associated circulatory overload or even an anaphylactic reaction. The majority of complications, however, come in the form of mild allergic reactions.
“There are protocols that they follow for evaluating whether or not it was the blood component that caused the problem or if there’s something else in that patient’s clinical history that could be the cause for the patient’s problem that they experienced during the transfusion,” said Uhl, discussing the event of a possible adverse reaction.
During a transfusion, protocol dictates that the patient is monitored continuously every 15-30 minutes. In the event of a complication, the laboratory takes on the role of a detective in figuring out what happened and what measures must be taken to ensure the safety of the patient. Any change in temperature beyond two degrees, changes in blood pressure, changes in heart rate, an outbreak of hives – all of these symptoms point to a potential reaction to the blood component, which means the transfusion must stop, additional samples must be drawn and a clerical check is performed.
The investigation continues with the laboratory performing a series of specific steps. The ABO typing is repeated, and if indicated, so are the antibody screening and cross-match tests. Once the laboratory evaluation is complete, the findings are communicated to the physician responsible for managing the blood bank, who performs a further investigation, reviews the patient’s chart and determines the nature of the complication – all while physicians continue to care for the patient and manage treatment for any reaction with which he or she might be presenting. Adverse reactions are rarely the result of an error in the blood banking process, however, but rather an unforeseen characteristic of the donor product – such as a foreign protein on the surface of the red cell.
“Sometimes the manifestation of hemolysis may be related to something else that’s going on with the patient,” continued Uhl. “So, for example: in the OR, one of the first signs of concern for hemolysis is that the patient’s urine turns red. Well, if they’re having a surgical procedure in the area of the kidneys or bladder or something like that, that could be the explanation for the red urine.”
For patients at increased risk for alloimmunization (e.g., patients with sickle cell disease), the laboratory must be especially careful in matching the recipient to the correct donor. There is a lot of research surrounding the development of alloantibodies in these patients, and while the need for precision is already vital in transfusion, it is unprecedented in the case of sickle cell disease. While the sheer number of transfusion these patients undergo could be a factor in alloimmunization, it is also argued that this could be due more to possible discrepancies between the donor and the recipient’s blood cells.
“Is it related to the volume of transfusion or the number of units that they see over time? Yes, it may, in fact, be,” said Uhl. “I think the other consideration that we are growing to appreciate is that there are differences in the donor population from the recipient population in terms of what proteins are on the red cell surface – and, so, that disparity may put the recipients at risk for forming alloantibodies.”
Starting with the initial donation and working all the way through to recovery, laboratory personnel play a vital role in ensuring the outcomes of transfusion patients. Donor blood is tested and matched to its intended recipient through a precise screening process, and then double-checked and labeled before ever being distributed. The best way to fight a complication from a potentially adverse reaction is to work as hard as possible to prevent it before the patient is ever transfused.