Microcirculation in preterm infants: profound effects of patent ductus arteriosus.

Objectives: To assess potential effects of a hemodynamically significant persistent ductus arteriosus (sPDA) in the skin microcirculation in preterm neonates.

Study Design: In 25 patients (<32 weeks of gestation; birth weight <1250 g) with sPDA (n = 13) or no significant PDA (non-sPDA; n = 12) functional vessel density and vessel diameters were investigated prospectively. Sidestream dark field imaging was performed in the skin of both arms from the third day of life until PDA closure or until day 7 or 8 for the non-sPDA group.

Results: Before PDA treatment, functional vessel density was significantly lower in the sPDA group compared with the non-sPDA group. In the sPDA group, there were significantly fewer large vessels (diameter >20 microm) and significantly more small vessels (diameter <10 microm). After successful PDA treatment, these differences disappeared. In both groups, functional vessel density differed significantly between the left and right arm, persisting even after successful treatment. Regression analysis showed an inverse linear correlation between the hemodynamic echocardiographic findings and functional vessel density (P <.005).

Conclusion: sPDA causes major changes in the microcirculation of premature neonates; functional vessel density is reduced, with a shift in perfusion from larger toward smaller vessels. The redistribution of flow might be a compensatory mechanism to preserve physiologic metabolism.