Scientists have, for years, been trying to develop artificial blood that would be free of all microbes that affect people; none of these products is available yet. In the meantime, experts believe the safest blood is your own. Procedures for collecting and using it include:
* Autologous transfusion: In the month prior to elective surgery, the patient donates three or four units (about a pint each) of his or her own blood, which is given back after the operation.
It is appropriate when the patient is healthy enough to give that much blood and has enough time, prior to the operation, to do it.
* Intraoperative autologous transfusion: During the operation, blood suctioned from the wound is collected in a sterile reservoir, washed and centrifuged to recover the oxygen-carrying red cells, which are then given back to the patient. Somehospitals have their own IAT equipment and technicians; others can request the machine and operator from the Red Cross or other blood technology agencies.
This is appropriate when blood from the operating site is not likely to contain contaminants. It is not used during surgery on the bowel, and it is not used during cancer surgery, for fear of spreading cancer cells. It is not perfect, either, warned Dr. Robert Wenk, medical director of transfusion medicine at Sinai Hospital: Three deaths have been associated with the technique, he said.
* Hemodilution: While the patient is being anesthetized, two units of blood are drawn; the patient is then given enough saline and albumin to maintain proper blood volume. The blood lost during the operation is thereby diluted with this unnecessary fluid; afterward, the patient is transfused with his own two units.
"We think hemodilution should be used more often," said Dr. Paul Ness, director of the blood bank at Johns Hopkins Hospital.
* Directed donation: A patient in need of transfusion rounds up relatives and friends to donate their blood; it must, of course, be of a blood type compatible with the patient's. More controversial than autologous transfusion, directed donation may be encouraged, discouraged, or grudgingly accepted by hospitals.
* Frozen autologous transfusion: Healthy people have several units of their blood frozen, to be used in case they need a transfusion at some future date. There are blood banks that offer this service, for a fee, though none, apparently, are operating in Maryland.
The advantage is the safety of having your own blood. "But what happens if you get hit by a truck in another city?" Dr. Wenk asked. "How are they going to get your blood out of a frozen blood store and get it to you in time?"