Introduction:
Anemia, described as low hemoglobin or hematocrit levels. The causes are multifactorial and include an immature hematopoietic system resulting in poor iron stores, decreased red blood cell lifespan, low erythropoietin levels, and frequent blood sampling. Anemia is often poorly tolerated, resulting in tachycardia, desaturation, apneic events, and poor feeding, and growth. When untreated, severe anemia may adversely affect organ function due to increase their cardiac output. And lead to inadequate oxygen supply, possibly resulting in anemic tissue hypoxia and injury . Anemia may also result in alterations in cerebral oxygenation and an increased risk for cerebral injury. Existing data raise concerns about the impact of anemia on both short- and long-term neurodevelopmental outcome . The underlying mechanisms for neurodevelopmental sequelae are multifactorial and incompletely understood, but known causative factors include cerebral hypoxia, ischemia, oxidative injury, and fluctuations in cerebral perfusion .It has been estimated that more than 90% of extremely low-birth-weight infants receive one or more RBC transfusions during their NICU stay . Transfusion thresholds remain controversial as RBC transfusions are associated with increased risk for ischemia-reperfusion damage or oxidative injury potentially resulting in transfusion-associated necrotizing enterocolitis, bronchopulmonary dysplasia and retinopathy of prematurity . Controversies about when to transfuse anemic preterm infants still remain . More research needs to be done to find superior indicators of perfusion and oxygenation to possibly use as transfusion markers. Hemodynamic measurements by Doppler study has the potential to provide criteria for Packed cell transfusion .