OBJECTIVENeonatal sepsis can cause multiple organ dysfunction syndrome, especially including myocardial injury and heart failure. In this study, the authors observed the changes and the levels of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide in myocardial injury of neonatal sepsis at the different stages to search for the early diagnostic index of myocardial injury and heart failure in patients with neonatal septicemia.

METHODThe levels of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide were determined in 96 newborns with neonatal septicemia according to the diagnosis and treatment program of neonatal septicemia in 2003. The 96 cases were divided into myocardial injury group and non-myocardial injury group. Every newborn was tested for the levels of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide with enzyme-linked immunosorbent assay (ELISA) on the second day, fifth day and tenth day of septicemia and in the different gestational age infants. Meanwhile, the results were compared to creatine kinase isoenzyme and troponin I.

RESULTThe levels of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide were significantly different between myocardial injury group and non-myocardial injury group at the fifth day (P<0.05), especially the levels of plasma N-terminal pro-B-type natriuretic peptide were significantly elevated at the early stage (on the second day) between the two groups (P<0.05). On the fifth day, the values of plasma N-terminal pro-B-type natriuretic peptide were (315.5 +/- 69.7) pmol/L in myocardial injury group, but the value of non-myocardial injury group was (179.3 +/- 27.5) pmol/L. On the fifth day, the results of plasma brain natriuretic peptide, N-terminal pro-B-type natriuretic peptide and troponin I were significantly different and had statistical significance between the myocardial injury group and non-myocardial injury group (P<0.05), while the results of creatine kinase isoenzyme had no statistically significant difference (P>0.05). The values of plasma brain natriuretic peptide were respectively (215.5 +/- 69.6) pmol/L and (119.3 +/- 37.4) pmol/L, While N-terminal pro-B-type natriuretic peptide were (315.5 +/- 69.7) pmol/L and (179.3 +/- 27.5) pmol/L in the two groups. The value of troponin I was (1.57 +/- 0.39) microg/L in the myocardial injury group and that in the non-myocardial injury group was (0.55 +/- 0.2) microg/L. The values of creatine kinase isoenzyme were (33.3 +/- 10.1) u/L in the myocardial injury group, but that of non-myocardial injury group was (17.4 +/- 8.5) u/L. In the different gestational age infants, the values of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide of premature infants were the highest in the three groups. The values of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide were (159.5 +/- 39.6) pmol/L and (238.5 +/- 49.7) pmol/L in premature infants.

CONCLUSIONThe levels of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide evidently increased in myocardial injury of neonatal sepsis, especially in premature infants. The increase of plasma brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide may be helpful in early diagnosis of the myocardial injury of neonatal sepsis associated with cTnI. N-terminal pro-B-type natriuretic peptide may become a useful index to diagnose the myocardial injury and should be widely used in the neonatal intensive care unit.