Early Postnatal Changes in the Superior Mesenteric Artery Blood Flow Parameters in Late Preterm Newborns - A Pilot Study

Significant hemodynamic changes happen in the abdominal region at the moment of birth and during the first week of life in premature newborns. The aim of the study was to assess early postnatal changes of Doppler sonographic blood flow parameters in the superior mesenteric artery (SMA) occurring during the first three days of life in late preterm infants. 10 infants were enrolled into the prospective study. Abdominal blood flow velocities (ABFV) in the SMA were obtained at the age of 2, 24 and 72 hours (h), before feeding. Screening parameters included the peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged mean velocity (TAMV). Doppler indices (DI) - resistance index (RI) and pulsatility index (PI) were calculated. EDV changed significantly from 2 h to 24 h [-13.08 cm/s (-20.46 - -9.34) to 12.79 cm/s (11.83 - 24.72); p < 0.01] with a further statistically insignificant increase within 72 h [12.79 cm/s (11.83 - 24.72) to 17.90 cm/s (16.93 - 19.25)]. The EDV values were negative in 9 out of l0 neonates at 2 h of age. The SMA PSV showed a daily increase from 2 h to 72 h. The ABFV and characteristics of vascular resistance (DI) in the SMA change significantly in near term infants within the first 3 days. At 2 h of age a negative blood flow and elevated parameters characterizing vascular resistance were documented in the superior mesenteric artery.