Normally this stimulates a significant increased production of erythropoietin (EPO), but this response is diminished in premature infants. Dear, Gill, Newell, Richards and Schwarz (2005) conducted a study to show that there is a weak negative correlation between EPO and Hb. The researchers recruited 39 preterm infants from 10 days of age or as soon as they could manage without respiratory support. They estimated total EPO and Hb weekly and 2 days after a blood transfusion. The study found that when Hb>10, EPO mean was 20.6 and when Hb≤10, EPO mean was 26.8. As Hb goes down, EPO goes up. While the reason for this decreased response is not fully understood, Strauss (n.d.) states that it results from both physiological factors (e.g., the rapid rate of growth and need for a commensurate increase in RBC mass to accompany the increase in blood volume) and, in sick premature infants, from phlebotomy blood losses. In premature infants this decline occurs earlier and more pronounced that it does in healthy term infants. Healthy term infants Hb rarely falls below 9 g/dL at an age of approximately 10–12 weeks, while in premature infants, even in those without complicating illnesses, the mean Hb falls to approximately 8g/dL in infants of 1.0-1.5 kg birth weight and to 7g/dL in infants <1.0 kg. Because this postnatal drop in hemoglobin level is universal and is well tolerated in term infants, it is commonly referred to as the “physiologic” anemia of infancy.
Aortopulmonary window (APW) refers to a congenital heart defect similar in some ways to persistent truncus arteriosus. Persistent truncus arteriosus involves a single valve; aortopulmonary window is a septal defect.A large number of patients with a large APW usually die within 1 year of age. It is extremely rare to find cases of APW surviving till adult age and it is still rare to surgically treat such patients who are incidentally detected in adult age because such subsets of patients invariably have associated pulmonary vascular obstructive disease in advanced stage and thus there is therapeutic dilemma to surgically correct these patients.Although cases of uncorrected APW presenting in adulthood have been reported but literature on surgically treated AP window in adult populations is limited. A rare case of successful surgical management of an incidentally detected large APW with reversible pulmonary arterial hypertension has been reported as isolated case reports. See also
Aortic window
Major aortopulmonary collateral artery, developes when native pulmonary circulation is underdeveloped

References


== External links ==