Citing a lack of clear guidelines for ordering blood transfusions during surgery, Johns Hopkins researchers say a new study confirms there the frequent use of transfused blood in patients who do not need it.
The resulting overuse of blood is problematic, the researchers say, because blood is a scarce and expensive resource and because recent studies have shown that surgical patients do no better, and may do worse, if given transfusions prematurely or unnecessarily.
“Transfusion is not as safe as people think,” said Dr. Steven M. Frank, leader of the study described in the journal Anesthesiology.
“Over the past five years, studies have supported giving less blood than we used to, and our research shows that practitioners have not caught up,” said Dr. Frank, an associate professor of anaesthesiology and critical care medicine at the Johns Hopkins University School of Medicine. “Blood conservation is one of the few areas in medicine where outcomes can be improved, risk reduced and costs saved all at the same time. Nothing says it’s better to give a patient more blood than is needed.”
The exceptions, Dr. Frank said, are cases of trauma, haemorrhage or both, where infusing blood quickly can be lifesaving.
General guidelines from three different medical societies govern when a surgical patient should get blood, but they tend to be vague, Dr. Frank said. In a healthy adult, a normal haemoglobin level — the quantity of red blood cells carrying oxygen through the body — is roughly 14 grams per decilitre. The guidelines state that when a patient’s haemoglobin level falls below six or seven grams per decilitre, a patient will benefit from a transfusion, and that if the levels are above 10, a patient does not need a transfusion. But when blood levels are in-between, there has been little consensus about what to do.
The recent studies, Dr. Frank said, suggest that physicians can safely wait until haemoglobin levels fall to seven or eight before transfusing, even in some of the sickest patients.
A Department of Health and Human Services committee complained last year of “both excessive and inappropriate use of blood transfusions in the US,” noted that “blood transfusion carries significant risk that may outweigh its benefits in some settings,” and stated that misuse adds unnecessary costs.
For the new study, Dr. Frank and his colleagues examined the electronic anaesthesia records of more than 48,000 surgical patients at the Johns Hopkins Hospital from February 2010 to August 2011. Overall, 2,981 patients (6.2 per cent) were given blood transfusions during surgery. The researchers found wide variation among surgeons and among anaesthesiologists, compared to their peers, and how quickly they order blood.
For example, patients undergoing cardiac surgeries received blood at much lower trigger points compared to patients having other surgeries. Patients undergoing surgery for pancreatic cancer, orthopaedic problems and aortic aneurysms, on the other hand, received blood at higher trigger points, often at or above 10 grams per decilitre.
The amount of blood transfused, Dr. Frank said, did not clearly correlate with how sick the patients were or with how much blood is typically lost during specific types of surgery. Blood is lost during many operations, though haemoglobin levels don’t often fall to the point where blood transfusion is necessary, he said.