Give blood! Somebody else needs it more than you do.

We've been going through a lot of blood in the NICU lately. It's been crazy busy and the babies are smaller and sicker than usual. Packed cells, platelets, sometimes back-to-back transfusions. It's amazing how much blood a 500 gram (little over a pound) baby can use over the course of a week. They only need it by teaspoonfuls, but they need it frequently. Fortunately, the blood bank can split the units so we can get several transfusions from one unit of packed red blood cells.

Packed red blood cells are the oxygen-carrying component of blood. One donor gives about 500 ml of blood in a donation. Something less than half of that is red blood cells. Most of the plasma (liquid portion) of the blood is removed so we can give more red blood cells in a smaller volume. This is done for both adults and children, but our babies are very fluid-sensitive, so we especially need packed cells for them.

Platelets are important in clot formation. Not enough platelets and the baby is at higher risk of intraventricular hemorrhage (bleeding into the brain) as well as excessive blood loss from minor injuries (like heel sticks for blood draws). We only use single-donor platelet units collected by apheresis (collection by way of a machine which removes the platelets and returns the rest of the blood to the donor).

Our blood bank reserves a unit of packed cells for each baby who needs a transfusion. They do the same thing with platelet units. The baby may get one transfusion, or several, from that one unit. It helps to limit the number of donors to which each baby is exposed. Our micro-preemies (under 750 grams) are still exposed to several donors in their first weeks of life.

We are grateful to every one of those donors. Nearly all of the blood donors are type O, Rh negative donors. With platelets, matching isn't so sensitive, so nearly any blood type can be used. However, all of them must be negative for viruses which are harmless to most adults, but which most of us have experienced, making us good donors for other adults, but not OK for babies or those whose immune systems are failing. CMV (cytomegalovirus) in particular is potentially lethal to newborns - or others with weakened immune systems. When you need O negative, CMV negative, blood, you're talking about a pretty small donor pool. Those people may find that their local blood bank is calling them every 8 weeks to make another donation.

Blood donations are down in general, but historically, they drop even lower around holidays when the need can be great. If you can make a little free time this week - or next, make an appointment with your local Red Cross or hospital volunteer donor blood collection center.

Been told you can't donate blood? Ask again. Some reasons for declining your blood will never change, but some policies have -- fairly recently. For example, cancer survivors who are in good health - even those who had chemo - are often accepted as blood donors. Those who had lymphoma or leukemia still can't donate, but many of the rest of us are being welcomed back to the donor rolls.