No one denies that blood can save lives. But experts agree that many of the 3.5 million Americans who receive transfusions each year are taking a needless risk. Smart surgeons already use an array of techniques to avoid transfusion therapy, and researchers are racing to develop others. Here are some of the strategies, proven and experimental, that could help keep anonymous blood out of your veins:
“The safest transfusion is no transfusion,” says Dr. Bernard Horowitz, vice president of the New York Blood Center. “The second safest is your own.” Autologous transfusions (using blood the patient has banked in advance) now account for an estimated 5 percent of the U.S. total-up from less than 1 percent a decade ago. But few experts expect the proportion ever to exceed 30 percent. Accident victims and premature babies don’t get a chance to donate in advance. Moreover, blood can’t be stored indefinitely: red cells, the vital oxygen-carrying component, expire after 42 days under refrigeration or 10 years frozen. And people with serious illnesses are often too weak or anemic to provide their own. Some patients opt for so-called directed donations from friends and family members, but most blood banks discourage that practice. They worry that donors may neglect, out of embarrassment, to reveal drug habits or sexual practices that place them at risk for HIV.
For more than a century, doctors have sought to give back the blood their patients shed during surgery. No one had much luck until 1974, when the Haemonetics Corp. of Braintree, Mass., started marketing Cell Saver, a machine that salvages vital red cells from a patient’s lost blood and prepares them for reinfusion (chart). Blood salvage isn’t possible in bowel or cancer surgery, since the lost blood is often tainted with tumor cells or bacteria. And the procedure can be more expensive than transfusion. But if a hospital is willing to use its Cell Saver liberally, it can all but eliminate donor blood from orthopedic and cardiovascular surgery. Through salvage and other techniques, surgeons at Chicago’s Northwestern Memorial Hospital now perform about 80 percent of all cardiac operations without a drop of outside blood.
A shot of erythropoietin (EPO), the hormone that governs the production of red cells, can help the body overcome a shortage or loss. Bioengineers have only recently learned to synthesize EPO. But in the three years since the substance hit the market, it has become a common treatment for the anemia associated with kidney failure, AIDS treatment and cancer. Premature infants may also benefit-and some experts suspect that a few shots of EPO before surgery could help prevent transfusions in the operating room. Unfortunately, presurgical treatment would be costly–about $1,000 per patient, according to the marketer–and the benefits are still unproven.
Common sense suggests that if a person receives intravenous fluids before surgery–expanding his blood volume and reducing the number of red cells in each pint–bleeding will be less hazardous to his health. Few U.S. doctors use hemodilution, as this technique is known, but it’s common among Jehovah’s Witnesses, who refuse transfusions on religious grounds. Blood can be diluted internally or during storage; it’s simply watered down with sterile solutions such as dextran and Ringer’s lactate. Hemodilution can cause fluid overload, which strains the heart. And since diluted blood carries less oxygen, doctors avoid the procedure if a patient is already anemic. But hemodilution can reduce many patients’ need for outside blood. In a 1990 study, Dutch doctors reported using the technique on 16 patients undergoing hip replacements, major abdominal surgery and other operations. Several patients lost more than 20 percent of their blood volume on the operating table, yet none received transfusions and none suffered any complications.
Since blood screening is never fool-proof, researchers are eager to find ways to kill viruses indiscriminately. Chemical treatment can safely sterilize some blood products, such as the clotting factors used to treat hemophilia. The standard process is toxic to red cells, but researchers are now perfecting gentler sterilization techniques. Dr. Alan Rubinstein of the University of Southern California has shown that a combination of sodium chlorite and lactic acid can kill viruses without harming red cells, and researchers at New York’s Albert Einstein College of Medicine have achieved promising results against HIV with a chemical called butylurea. Future Medical Products, which holds a joint patent with the university, is now preparing to market the procedure to blood banks.
Venture capitalists have long dreamed of coming up with a substance that could take the place of natural hemoglobin, the molecule that enables red cells to transport oxygen. The appeal is obvious: no one would need to worry about viruses; trauma victims would be able to get the stuff immediately, regardless of their blood type; and manufacturers could profit mightily. Some 15 companies are now racing to develop a blood substitute, and they’re taking two basic tacks. Some firms are trying to harvest or synthesize actual hemoglobin, while others hope to replace it with compounds known as perfluorocarbons. Northfield Laboratories of Evanston, Ill., Alliance Pharmaceutical of San Diego and Somatogen of Boulder, Colo., are now conducting human safety studies, but major hurdles remain. Commercial licenses are still at least several years away. Producing a truly safe, affordable, all-purpose blood substitute could take decades.
Doctors have, by all accounts, grown warier of donor blood during the past decade, yet there’s abundant evidence that blood is still overused. Several studies have shown that a heart-bypass patient’s chances of receiving a transfusion depend on where he’s treated, not on the seriousness of his condition. And hospital audits typically deem 5 to 20 percent of transfusions unnecessary. Three federal panels have called on doctors to cut back. Some hospitals have responded by barring doctors from ordering blood without first consulting a review committee. Yet a 1990 survey found that a third of hospitals don’t even have such committees.
For now, experts agree, the best way to reduce transfusion-associated illness is simply to teach physicians more restraint. By tradition, surgeons have ordered blood whenever a patient’s hemoglobin count drops to two thirds of the normal level. In clinical guidelines published this year, the American College of Physicians affirms that healthy people can tolerate less than half the normal hemoglobin level. As three experts write in support of the new guidelines, “The age-old transfusion trigger is no longer defensible.” If your doctor tells you otherwise, it may be time to switch doctors.
Salvaging a surgery patient’s blood can reduce the need for outside transfusions.
Blood shed during surgery is sucked into a reservoir; then pumped into a centrifuge, where oxygen-carrying red cells are separated from plasma.
The plasma goes into a waste bag. Saline solution removes platelets and other debris. Red blood cells return to the patient through an IV.
