Sinai Hospital has launched a program to conserve one of the world's most valued resources.
Years ago, a doctor didn't give too much thought to drawing vial upon vial of blood to monitor the swings of a patient's health. If patients lost so much blood they verged on anemia, a transfusion could always provide the needed boost.
Today, transfusions remain an important weapon in a doctor's treatment arsenal. But in the age of AIDS, the small but real risk that a transfusion could cause unwanted infections has spurred research into ways to limit the amount of blood a patient must give up for medical tests.
Inside Sinai's intensive-care unit, Dr. Bart Chernow is bent on reducing blood loss to a relative trickle. The heart of it is a bedside machine that performs a battery of crucial tests on just a few drops of blood -- about 20 percent of the blood volume required by conventional laboratory equipment.
"It's time that we, as critical-care physicians, started thinking about this precious commodity -- blood -- that we take from patients," said Dr. Chernow, who left a post three months ago at the Harvard Medical School to become Sinai's chief physician.
Dr. Chernow's interest in blood preservation grew out of his observations of what happened to many patients who entered intensive-care units with blood counts already lowered by illness.
Their blood counts -- the concentration of oxygen-carrying red cells in the bloodstream -- would decline steadily. Every few hours, nurses would draw about 10 milliliters of blood -- the equivalent of two tablespoons -- to give doctors up-to-the-moment profiles of patients' improving or declining health. Five tests a day meant 50 milliliters, and in only five days of this routine patients would give up the amount a healthy person donates at a bloodmobile.
"We're dealing with very sick people who have lost their margin of safety in terms of their blood count," Dr. Chernow said. "What we've done is tip them over the edge -- and eventually, they may need a blood transfusion."
In contrast, blood donors can afford to give up a considerable amount of blood because their reserves are higher to begin with and their bone marrow is able to replenish the lost blood within a few weeks.
Three months ago, Sinai began sparing patients much of their blood loss through the miracle of microchemistry -- a burgeoning technology that has given hospitals the ability to get a blood profile from a few drops of blood.
Dr. Chernow and a research fellow, Dr. Michael Salem, tested a TV-sized microchemistry machine on 300 patients at Massachusetts General Hospital in Boston and 500 patients at Sinai. Analysis showed the machine to be as accurate as conventional equipment, which requires about five times as much blood.
As an added bonus, the portable machine rolls to a patient's bedside and displays results with a minute or two, both on a video monitor and on paper tape. When doctors send blood samples to a hospital laboratory, results take about a half-hour, Dr. Chernow said.
The machine, which costs about $40,000, has been commercially available for about two years. "I will predict that at least one-half of the ICUs in the city will use this within a year," said Dr. Chernow, who believes Sinai is the only hospital in Baltimore now using one on the floor of its intensive-care unit.
Sinai also has taken steps to limit the amount of blood it wastes. Typically, nurses drawing blood through plastic tubing end up discarding a short column of blood that inevitably remains in the tube once they have syringed out the sample they need.
But new tubing comes equipped with tiny bellows that enable nurses to pump this residual blood back into the patient's arm -- ensuring that not a drop is wasted.
Blood preservation doesn't end there. Patients with kidney failure now get pharmaceutical supplements of erythropoietin, a hormone that stimulates the bone marrow to produce red cells. Healthy kidneys secrete required amounts of the hormone, but people with failing kidneys often need blood transfusions to prevent anemia.
Despite his zeal to prevent transfusions where possible, Dr. Chernow emphasizes that the chance of contacting an infection from a transfusion -- be it AIDS, hepatitis or other viral illnesses -- is minuscule.
"The thing we're saying is that the risk is small but it's a real risk," he said.
"What we're trying to do is limit the number of times we need to take those risks."