Clinical and genetic risk factors for moderate hyperbilirubinemia in Brazilian newborn infants

OBJECTIVE

To identify clinical and genetic risk factors for moderate hyperbilirubinemia during the first week of life.

STUDY DESIGN

Using univariate and multivariate multiple regression analyses, the RR for clinical factors, the African variant of glucose-6-phosphate dehydrogenase (G6PD) deficiency (G202A/A376G), and (TA)(n) UGT1A1 polymorphisms were established in a cohort of 608 Brazilian newborn infants. Hyperbilirubinemia was monitored until 134.5 ± 49.8 h of life (IQR, 111.0 to 156.7). The dependent variable was total bilirubinemia (TB) ≥12.9 mg per 100 ml estimated by transcutaneous or plasma bilirubin measurements.

RESULT

The African variant of G6PD deficiency and (TA)(7)/(TA)(7) and (TA)(7)/(TA)(8) polymorphisms present in 6.1 and 12.0% of newborns, respectively, were not risk factors for moderate hyperbilirubinemia. Coexpression of G6DP deficiency and UGT1A1 polymorphisms occurred in 0.49% of the subjects. Independent clinical predictors for TB≥ 12.9 mg per 100 ml were gestational age <38 weeks and reference curve percentiles >P40th.

CONCLUSION

In this study, G6PD deficiency and UGT1A1 gene promoter polymorphisms were not risk factors for moderate hyperbilirubinemia. Genetic factors may vary considerably in importance among different populations.

[Prolonged esophageal pH monitoring utilization in the diagnosis of pathologic reflux in neonates]

OBJECTIVES: To present indications and results of prolonged esophageal pH monitoring in diagnosing pathologic gastroesophageal reflux in newborns during their stay in the neonatal unit. METHODS: This retrospective descriptive-analytical study of 85 prolonged esophageal pH monitoring in neonates was performed, between October 1995 and March 1998, in a tertiary intensive care unity. A Digitrapper MKIII device, pH probes with one or two channels, and antimony electrodes were utilized. The probe was placed 3 cm above the gastroesophageal junction. RESULTS: The main indications of this esophageal pH study were hypoxemia episodes demanding supplemental oxygen, and caffeine resistant apnea. The means -/+ SD of birth-weight and gestational age in the patients evaluated were, respectively, 1,204-/+460 g and 30.5 -/+ 2.9 weeks. There was no statistical difference observed in newborns with and without pathologic gastroesophageal reflux according to clinical manifestations and monitoring conditions. Forty-eight newborns (56.4%) presented 17.6-/+9.1% of the whole examination time with a pH below 4. Of these patients, 31.1% presented birth-weight below 1,000 g. Duodenogastroesophagic was diagnosed in two cases. Of the studied premature with chronic lung disease, 66.7% presented pathologic reflux. CONCLUSION: Prolonged pH esophageal monitoring is helpful in the differential diagnosis of the unspecific and very frequent clinic manifestations in very low birth-weight infants.

Gastric emptying of a liquid meal in experimental chemical pneumonitis

Gastric emptying of a liquid test meal was studied in an experimental model of chemical pneumonitis. In the first phase, 160 microliters of a hydrocarbon mixture was injected iv into 10 young adult rats, and the same volume of saline solution was injected into 10 controls. Arterial blood gases and lung dry and wet weight were determined. In the second phase, gastric emptying of a 5% (w/v) glucose solution marked with phenol red (6 mg/dl) was studied 5, 10, 20 and 30 min after orogastric infusion of the test meal. Gastric retention was determined by measuring the concentration of the marker in the residual test meal recovered from the stomach after killing the animal. Thirty-two experimental and 32 control animals were paired and eight pairs were used at each time. The wet weight and external volume of the lungs were determined in all animals and 20 experimental animals were analyzed histopathologically. The animals of the experimental group developed intense macro- and microscopic pulmonary alterations. PaO2 values (mean +/- SD) at the first (70.7 +/- 5.9 mmHg) and fifth hour (71.1 +/- 8.5 mmHg) were significantly lower than the respective values obtained for the control group (109.5 +/- 13.5 and 113.9 +/- 11.2 mmHg). Gastric retention at 5, 10, 20 and 30 min was significantly higher in animals with pneumonitis (median: 59.1%, 55.4%, 45.3%, 27.2%) when compared to respective values for the control group (median: 47.5%, 46.6%, 24.1%, 19.3%). These results indicate a delay in the gastric emptying of liquids in serious pulmonary disorders.(ABSTRACT TRUNCATED AT 250 WORDS)