tailieunhanh - Ebook Key topics in neonatology (2/E): Part 2

(BQ) Part 2 book “Key topics in neonatology” has contents: Maternal drug abuse, mechanical ventilation, metabolic acidosis, multiple pregnancy, necrotising enterocolitis, neonatal surgery, n eural tube defects, n eurological evaluation, patent ductus arteriosus, and other contents. | Jaundice All neonates have a transient rise in bilirubin, and some 30–50% become visibly jaundiced. Preterm and term infants become jaundiced for similar reasons as follows: • increased bilirubin load on the liver due to a high red cell mass, the shorter survival of the neonatal erythrocyte, and the increased intestinal reabsorption of bilirubin (the enterohepatic circulation) • decreased hepatic uptake of bilirubin from the circulation • impaired bilirubin conjugation. The bilirubin excretory pathway is therefore both overloaded and operationally inefficient, leading to a transient unconjugated hyperbilirubinaemia that peaks around day three, fades rapidly over the next three days, and clears by days 10–14. Hyperbilirubinaemia is more pronounced and almost universal in preterm infants, as a result of hepatic and gastrointestinal immaturity. The delayed initiation of enteral feeds in sick preterm infants (which further enhances the enterohepatic circulation) and the slower maturation of hepatic bilirubin uptake and conjugation contribute to the greater magnitude and duration of jaundice in these infants. Jaundice in neonates is considered as either physiological or pathological. Physiological jaundice is the consequence of transient immaturity and the inefficiency of the bilirubin conjugation and excretory pathways. Prematurity, bruising, polycythaemia, breast-feeding, and other factors can increase physiological jaundice (sometimes to the point of needing treatment). Jaundice is pathological and important if: • It is in the first 24 h of life—haemolysis until proven otherwise. • It is associated with another illness. • The bilirubin concentration is above the normal range. • It has become prolonged (>10 days at term; >14 days in preterm infants). Term infants The 97th percentile for bilirubin concentration in the first few days of life in the well, breast-fed term baby is approximately 250 µmol/l, and it is 210 µmol/l in the formulafed baby. These thresholds of .