END OF BLOOD USE
But when they’re put into someone else, they can suppress the immune system.
More recent studies have shown that transfusion-related reactions have fallen since blood suppliers began washing white blood cells from blood. However, Dr. Aryeh Shander, clinical professor of anesthesiology, medicine and surgery at Mount Sinai School of Medicine in New York, says that while there has been an unquestionable reduction in fever rates, “the rest is debated.”
Shander helped create the bloodless medicine and surgery program at Englewood Hospital and Medical Center in Englewood, N.J. He says that “old habits die hard” and that too many doctors believe “something bad will happen” if patients don’t have a certain volume of blood in their system.
The biggest driver of red-bloodcell transfusions is hemoglobin, the protein in red blood cells that ferries oxygen from the lungs to tissues and cells throughout the body. Too little hemoglobin, and the person becomes anemic. Red blood cells are frequently transfused during cardiac surgery, prostate surgery, joint replacements and in patients bleeding from their intestinal tracts.
But, once removed from the body, red cells undergo changes in their shape and function. Their membranes deteriorate; some cells burst, releasing free hemoglobin, which mops up nitric oxide, the chemical that helps blood vessels relax. There are now growing concerns that “older” red cells stored for longer than a few weeks lose some of their ability to transport oxygen — the very reason they’re transfused. In Canada, red cells are stored for up to 42 days.
When he was in medical school, Ottawa critical care specialist Dr.
‘The biggest challenge is trying to change the behaviour of physicians. People are being transfused at hemoglobin levels higher than they need to be.’ DR. ALAN TINMOUTH Hematologist and scientist at The Ottawa Hospital Research Institute
Paul Hebert, whose research has transformed transfusion practices worldwide, was taught that seriously ill patients need a high level of hemoglobin to keep diseased or damaged tissues alive. So ingrained was this belief that anesthesiologists and surgeons routinely began transfusing surgery patients if their hemoglobin dipped below a certain number (100 grams per litre of blood).
In a landmark paper published in the New England Journal of Medicine, Hebert and his team found that patients who were only mildly below that hemoglobin cutoff, but who were treated aggressively with transfused blood nonetheless, were more likely to die, and had higher rates of organ failure, than patients whose doctors held back until their hemoglobin fell to lower levels.
“We found that, if you give less blood, you do better,” Hebert said. “We think that’s because many of the patients didn’t need it in the first place.”
In a study published in January 2013, Hebert and co-authors reviewed 19 trials involving more than 6,000 patients that compared higher versus lower hemoglobin thresholds in red-blood-cell transfusions. They found that patients could be transfused at hemoglobin levels of 70 or 80 grams per litre of blood without putting them at any increased risk for major complications such as pneumonia, stroke, infection, or death. If doctors were to use the lower thresholds, “I think you can reduce blood use in many settings by at least half,” said lead author Dr. Jeffrey Carson, chief of the division of general internal medicine at Rutgers Robert Wood Johnson Medical School in New Brunswick, N.J.
A recent review of blood transfusions at three Ontario hospitals found that the pre-transfusion hemoglobin levels were higher than the recommended thresholds for many patients.
Some transfusion rates have been falling since the province established a network of blood transfusion co-ordinators in 25 hospitals. A major thrust of the program is to treat patients with anemia — low hemoglobin — before surgery “so that we avoid having to transfuse them when they bleed,” said Dr. John Freedman, medical director of the program and professor emeritus at the University of Toronto.
British Columbia created the first transfusion registry in Canada in 1999; it remains one of the largest in North America. The database tracks every unit of blood that gets transfused into someone in B.C. or the Yukon.
Within the year, The Ottawa Hospital hopes to have a computerized system in place to capture where blood is going, which patients are being transfused and their hemoglobin levels at transfusion.
According to Canadian Blood Services, Canada is at the lower end of blood use worldwide, and experts say it would be dangerous to attempt to cut transfusions rates to near zero.
As well, demand for blood is expected to grow as the population ages, because older people use more blood.
While Jehovah’s Witnesses have taught doctors that the body can compensate for extraordinarily low levels of hemoglobin, levels that are too low mean the cells and tissues in the brain and other vital organs become starved of oxygen.
Hebert has watched Jehovah’s Witnesses die for refusing to be transfused, an experience that leaves the medical team feeling helpless. “But you can’t force your values on someone else,” he says.
Hebert says more research and education is needed to help doctors decide how long they can safely wait before ordering blood, how much blood they should give and when to hold off giving any blood at all.
“The problem is that we don’t have the data,” Hebert said. “In many cases, we just don’t know.”