Atrial natriuretic peptide, volume and blood pressure regulation during exchange transfusion of the neonates.

Plasma concentrations of atrial natriuretic peptide (ANP) and hemodynamic parameters were investigated in five premature infants undergoing exchange transfusion. Baseline values of ANP were elevated being 51.7 +/- 21.2 fmol/ml. Volume depletion by withdrawal of 10 ml blood did not cause changes in systolic blood pressure (79.4 +/- 4.3 vs 71.4 +/- 5.6 mmHg) and heart rate (115 +/- 5.2 vs 115 +/- 2.4 l/min). ANP levels in plasma remained unaltered (53.4 +/- 24.9 fmol/ml). Volume load of 10 ml blood transfusion increased central venous pressure by 33 per cent and ANP concentration in the plasma nearly by 30 per cent, while heart rate and blood pressure remained unchanged. Our data indicated that the heart of premature infant responds to acute volume load by increased ANP-release, while volume depletion seems not to influence hormone regulation.