Ontogeny of bilirubin-binding capacity and the effect of clinical status in premature infants born at less than 1300 grams.

BACKGROUND: Bilirubin is toxic to the brain and enters the brain in unbound form. Serum unconjugated, unbound bilirubin may be a good predictor of bilirubin encephalopathy. Unbound bilirubin levels may depend on the bilirubin-binding capacity of albumin, which has not been described for neonates of <28 weeks' gestation. OBJECTIVE: The purpose of this work was to determine the ontogeny of bilirubin-binding capacity and the effect of clinical status in very preterm neonates. METHODS: A total of 152 neonates (23-31 weeks' gestational age; 440-1300 g) were enrolled prospectively. At 5 days of age, total serum bilirubin and unbound bilirubin were measured with the unbound bilirubin-A1 analyzer (Arrows Co, Osaka, Japan) and albumin with the Bromocresol-purple method. Scatchard plots were used to estimate bilirubin-binding affinity and capacity. Clinical status for each infant was rated as high, moderate, or low risk by using a modified Score for Neonatal Acute Physiology model. Low risk was considered clinically stable. RESULTS: Unbound bilirubin has a significant, direct correlation to total bilirubin and is greater in unstable than in stable neonates. For the entire cohort, bilirubin-binding capacity had a direct relationship to gestational age. The bilirubin-binding capacities of infants in the low- and high-risk groups also had a direct relationship to gestational age. Bilirubin-binding capacity was greater in the low-risk group (20.8 +/- 4.6 mg/dL; 356 +/- 79 micromol/L) than in the moderate- (17.8 +/- 3.5 mg/dL; 304 +/- 60 micromol/L) or high- (17.3 +/- 3.4 mg/dL; 296 +/- 58 micromol/L) risk groups. Bilirubin-binding affinity did not differ by clinical risk status or gestational age. CONCLUSIONS: In very preterm, very low birth weight infants, bilirubin-binding capacity is directly proportional to gestational age. Bilirubin-binding capacity is lower and unbound bilirubin higher in unstable than in stable neonates. These data may be useful in guiding the management of hyperbilirubinemia in very low birth weight infants.

Is retinopathy of prematurity increasing among infants less than 1250 g birth weight?

OBJECTIVE: Retinopathy of prematurity (ROP) is a complication seen in many very low birth weight infants. Severe ROP has been called a "marker" for severe disability. The purpose of this study was to evaluate the occurrence and severity of ROP among infants < or =1250 g birth weight treated in the Special Care Nursery at Women & Infants' Hospital over a period of 7 years from 1994 to 2000. STUDY DESIGN: This was a retrospective review of ROP data combined with neonatal follow-up data. Of the 1002 infants born with birth weights <1250 g, ophthalmologic data were available for 739 of 839 survivors. Analysis of variance and chi2 along with logistic regression were used to analyze outcomes. RESULTS: An increase in the overall occurrence of ROP was identified (40% to 54% linear trend, p=0.007). The occurrence of threshold ROP ranged from 2% to 5% (NS). Infants at greatest risk of ROP were those micropremies with birth weights <750 g (p<0.001). CONCLUSION: Severe ROP continues to be a significant morbidity among infants <750 g.

Congenital familial hypertonia.

1. This complex of symptoms appears to be congenital, familial, and hereditary. It is apparently transmitted by a dominant gene, probably on chromosome 5. 2. Hypertonicity with rigidity of all voluntary muscles usually presents at birth. 3. Feeding problems are due to dysphagia or laryngospasm associated with aspiration and dyspnea. 4. Respiratory problems are characterized by apneic episodes due to muscle spasm. 5. Prolonged episodes of muscular rigidity secondary to sudden stimuli result in frequent falls, characteristically en bloc, like a statue. 6. Continuous electromyographic activity even at rest (with absence of fasciculations) improves after intravenous diazepam.