The Cochrane Library: Evidence-Based Medicine November 9, 2011

Low versus high haemoglobin concentration threshold for blood transfusion for preventing morbidity and mortality in very low birth weight infants

Robin Whyte, Haresh Kirpalani
Cochrane Neonatal Group

Plain language summary

Very premature infants are extremely vulnerable and often require intensive care to survive. Anaemia is a condition in which the blood does not contain enough haemoglobin, the component of red blood cells which carries oxygen around the body. These babies become anaemic very quickly due to blood sampling and because they are unable to make blood cells quickly the haemoglobin level in the blood falls rapidly in the weeks after birth. Generally, the treatment for anaemia is blood transfusion, and many of these babies receive multiple transfusions of blood. The decision to give a transfusion usually depends on the measured amount of haemoglobin in the blood.

Physicians looking after very premature infants are unsure as to the level of haemoglobin at which they should give a transfusion. As transfusion is the introduction of another person's blood cells into the blood stream, there is a risk of infection and a risk of reaction to foreign blood components; the process requires careful monitoring and supervision to ensure safety. Some people find blood transfusion offensive or contrary to their religious values. Giving few or no transfusions reduces the risks of transfusion, but may result in low levels of haemoglobin and consequently a reduced supply of oxygen to the body which could have effects on survival, growth or development.

This review of five studies compares the effects of blood transfusion at low levels of haemoglobin to transfusion at high levels. Within the levels tested, there were no differences seen in survival, in the serious complications of prematurity, or in longer term development as measured at 18 to 21 months past the baby's due date. Allowing the baby to become a little more anaemic did not affect the baby's weight gain or breathing patterns. These conclusions are not firm, because too few babies have been studied. Our overall recommendation is not to exceed the higher levels of haemoglobin used in these trials, and thus diminish the risks of over-transfusion, but not to allow the level of haemoglobin to fall below the lower limits tested in these studies until further studies are completed.