Formula Predicts Blood Needs for Heart Surgery

Researchers have developed a simple formula that will enable anesthesiologists to predict, based on individual patient characteristics, how much blood to have on hand in the operating room prior to coronary artery bypass surgery (CABG).

In the study, researchers from Duke University Medical Center (Durham, NC, USA) analyzed the charts of 5,402 consecutive patients who received a bypass procedure at Duke University Hospital between 1993 and 2002. They correlated blood use during the first 24 hours after surgery with 13 different patient characteristics, such as anemia before surgery, age, gender, weight, heart and kidney function, tobacco use, and other accompanying illnesses. For the first two-thirds of the patients, they determined which characteristics led to greater blood use. They then developed the formula based on those findings and tested its predictive abilities on the last third of patients.

The simplified scoring system devised by the team would identify risk factors for transfusion. The patients who are most likely to need the most blood during or immediately following their surgery are those who are over the age of 75, those who have impaired kidney function, and those who weigh less than 121 pounds. The results were presented at the annual scientific sessions of the Society of Cardiovascular Anesthesiologists, held during April and May 2006 in San Diego (CA, USA).

"We thought there needed to be a better way to estimate blood needs, since blood is a scarce commodity that takes staff time and resources to prepare,” said George Lappas, M.D., a cardiovascular anesthesiology fellow who presented the Duke team's results.

Before a bypass procedure, blood typically is delivered to the operating room in case it will be needed to replace blood lost during surgery. The reserve blood must be matched with the patient's blood type, and it also must be cross-matched by mixing it with the patient's blood to test for adverse immunologic reactions.



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