Science-- there's something for everyone

Saturday, December 24, 2011

Less blood needed

Most healthy people have hemoglobin levels that fall between 12 and 18 grams per deciliter of blood (g/dl). Currently, patients undergoing surgery are routinely given blood transfusions if their hemoglobin levels drop below 10 g/dl or if they have any of a number of other risk categories, such as old age or heart disease.  Jeffrey Carson of Robert Wood Johnson Medical School and a large team of colleagues tested whether these rules could be safely relaxed for patients undergoing hip surgery.  This turned out to be the case, even for elderly patients.

Matched patients around eighty years old who required hip surgery were randomly assigned to two groups of about a thousand people each. The liberal group automatically received blood transfusions if their hemoglobin levels dropped below 10 g/dl. The restricted group did not receive blood unless their hemoglobin levels fell below 8 g/dl, or they showed clinical signs of anemia.  All patients were allowed transfusions at the discretion of their doctors.

Thirty and sixty days later, the patients were surveyed on their ability to walk.  The doctors hypothesized that maintaining a higher hemoglobin level might have allowed patients to work harder at their rehabilitation, resulting in greater independence two months after surgery.  Other consequences, such as rates of heart attack, pneumonia and death were also determined for the two groups. 

As I’m sure you’ve guessed, there were no significant differences between the two groups in either ability to walk unassisted, length of hospital stay or clinical outcomes. However, the patients in the restricted group used 65% fewer units of blood.  This is important because many hospitals suffer from a critical lack of transfusable blood.  If most surgical patients could safely be given little or no blood, it would free up the supply for patients who truly need transfusions.