Experts confront the hidden hazards of transfusions
Deaths from an incompatible procedure are rare in Canada, but they do happen — and they are also entirely preventable, writes SHARON KIRKEY.
It is euphemistically known as “wrong blood in tube”: a transfusion error that ends with a patient receiving blood meant for someone else. Sometimes that patient is lucky and still gets his or her own blood type. The error isn’t even caught.
In the worst cases, however, “mismatches” can kill by causing a rapid and catastrophic reaction in which the person’s body starts destroying the red blood cells almost immediately after infusion.
Death from an incompatible blood transfusion is rare in Canada, but it happens. And every one is entirely preventable.
New Canadian research is raising fresh concerns over the sheer magnitude of the frequency and types of transfusion errors that are occurring, from the moment blood is ordered until the clamp on the IV is opened to start the transfusion.
Experts say that while vast amounts of money have been spent on making blood safer from infectious diseases since the taintedblood tragedy of the 1980s, too little has been done to make the actual transfusion of blood safer.
The Public Health Agency of Canada runs a surveillance system for transfusion injuries. The last public report the agency issued was for 2004-05.
That year, of the more than two million transfusions documented, 762 “adverse events” were reported, including 11 deaths. Seventeen cases of incompatible transfusions were documented; most involved red blood cells. More than one-third of them were life-threatening.
The top three reported injuries were: fluid overload, where patients are given more blood than their bodies can handle, causing swelling throughout the body or difficulty breathing; severe allergic reactions; and serious lung injuries that can cause respiratory distress. Overall in 2005, the risk of an adverse event was one in every 3,270 units transfused.
Another government blood surveillance system — this one tracking transfusion-related errors — identified 31,989 errors between January 2005 and December 2007 among 11 participating hospitals. Nearly 3,000 errors, almost one in 10, were classified “high severity” errors with the potential to cause serious harm, including death.
Experts say that the risks posed by transfusion errors or adverse reactions to blood exceed the risk of contracting a virus from blood by up to 10,000-fold, making it even more vital to avoid giving blood in the first place to patients who don’t need it.
Yet researchers at Toronto’s Sunnybrook Health Sciences Centre, who tracked transfusion errors over a six-year period at their hospital, found that of 23 errors that harmed patients, virtually all involved unnecessary transfusions.
In all, a total of 15,134 errors were reported over 72 months. For every error that harmed a patient there were 657 errors that were detected and intercepted before the blood could reach the patient. “Wrong blood in tube” — blood drawn from the wrong patient for matching — occurred once in every 10,250 samples collected.
“One of the leading causes of major morbidity (sickness) from a blood transfusion is just getting blood that wasn’t intended for you,” said Dr. Jeannie Callum, director of transfusion medicine at Sunnybrook.
This is how the error can happen: Two patients are sharing a semi-private room. Patient A needs a blood transfusion. A sample of blood needs to be taken to match the blood type with the donor blood. But the nurse mistakenly takes the blood sample from patient B, and then puts patient’s A name on the tube of blood that’s sent to the lab. Patient A ends up getting transfused with Patient B’s blood type. “Or, I’m a group O and someone inadvertently gives me blood that was intended for the patient in the next bed,” Callum explained. “I can have an incompatible reaction that puts me into kidney failure and can threaten my life.”
Some “wrong-blood-in-tube” mistakes are hidden and never caught because the patient is transfused with a blood type matching his or her own. “Many times, you may just get lucky,” said Dr. Alan Tinmouth, a hematologist and scientist at The Ottawa Hospital Research Institute. The error “doesn’t cause a severe reaction, or maybe the blood is still compatible. Group O blood went to a group O patient.”
In cases where the blood is incompatible, some people can survive receiving two units of mismatched red blood cells. Some die after receiving one unit. Even if transfused properly, blood is a biological product, a liquid organ transplant, that can cause reactions, particularly respiratory reactions, in recipients.
One of the major reactions is TRALI: transfusion related acute lung injury, the leading cause of transfusion-related deaths. It can happen with any type of blood product and often starts within an hour after the transfusion begins.
Most cases occur when antibodies in the blood of some donors react with incompatible proteins in the recipient, triggering an immunological reaction. The person suddenly has trouble breathing. Fluid accumulates rapidly in the lungs and blood oxygenation levels plummet. The fatality rate ranges from five to 14 per cent.
“Everyone, when they think about transfusions, always worries about infections, with good reason, (given) the tragedies that happened in the 1980s,” Tinmouth says. Today, the risks of HIV and hepatitis C from donor blood are so small, “we actually can’t measure them.”
But there are other risks, he said, including, with platelets, the risk of bacterial contamination because platelets have to be stored at room temperature. “And those bacterial infections can be very serious,” Tinmouth said.
Callum, of Sunnybrook, says more needs to be done to make sure that patients only get blood when it’s necessary and that the right blood goes to the right patient, at the right dose.
Sunnybrook is bar-coding patients in areas with high transfusion rates, including surgery patients. Handheld devices scan bar codes on patient’s wristbands, then churn out labels at the bedside when a sample of blood is drawn for matching. The patient ID band and the “bag tag” label on the blood product are also scanned before the bag is hung, “and if they don’t match, an alarm goes off that says, ‘We’ve got the wrong patient here,’ ” Callum said.
Technologists at Sunnybrook are also scrutinizing every order for blood for compliance with hospital guidelines. “We basically block transfusions that should not be occurring,” she says. In “non-bleeding,” non-urgent cases, only one unit of red blood cells is issued at a time to make sure no patient gets more blood than he or she needs.
Experts stress that serious, lifethreatening reactions are infrequent in comparison to the total number of transfusions. For example, nine deaths were reported to the federal government’s transfusion injuries surveillance system for the year 2006, for a rate of one death per 130,122 units transfused.
But 10 per cent of hospitalized patients receive blood, Callum said.
“Sometimes when the patient has had a bad reaction, we look back at how the patient was managed and we say, ‘Did that patient even need that blood product?’ ”