Perioperative Urinary NT-ProBNP Values and Their Usefulness as Diagnostic and Prognostic Markers in Children with Congenital Heart Disease

Objectives: NT-ProBNP is an important marker in patients with congenital heart disease (CHD). Preoperative NT-ProBNP values determined from a urine sample and corrected to creatinine in that same sample correlate well with the plasma values of NT-ProBNP. Changes in NT-ProBNP levels in children with CHD have a greater prognostic value than the absolute value. This study looked at the development of plasma and urinary values of NT-ProBNP from before the operation to the third postoperative day. Postoperative extubation and weaning from mechanical ventilation play a key role in the treatment of children after cardiac surgery. We looked at the prognostic value of changes in NT-ProBNP levels in predicting prolonged weaning from ventilation.

Methods: We investigated 83 children, undergoing cardiac surgery for a myriad of CHDs. The underlying condition was classified into simple versus complex CHD. Urine and plasma samples were collected at six time points; the first sample was collected on the day before the operation, the second after the child was intubated. Postoperative samples were collected during the first three postoperative days. The urinary values were corrected for the urine concentration by calculating the quotient of NT-ProBNP to creatinine. Due to a skewed distribution data was transformed into Lg10-values.

Result: Although the correlation coefficient between urine and plasma values is weaker postoperatively (r = 0.70–0.78), in comparison to (r = 0.87) preoperatively, the correlation remains significant with a two-sided significance of 0.00. Neonates had higher urinary values than older children (t-test value of −6.10 with a two-sided sig. of 0.00). The validity of NT-ProBNP in the discrimination between children with complex versus simple CHD was examined using an ROC-analysis, the area under the curve for plasma values was 0.896; while the area under the curve for creatinine corrected urine values of NT-ProBNP was 0.826. A steep decline of NT-ProBNP plasma values from the day before the operation to the time after intubation and insertion of lines, correlated with the duration of postoperative noninvasive ventilation (r = 0.9 with a two sides sig. of 0.00).

Conclusion: This study examines urinary NT-ProBNP perioperatively in children with CHD and shows potential in discriminating between complex and simple CHD. It is the first to show the prognostic role of NT-ProBNP in establishing spontaneous respiration postoperatively in children with CHD.

Publication History

Article published online:
21 February 2021