Correlation of abdominal rSO2 with superior mesenteric artery velocities in preterm infants

OBJECTIVE: Near-infrared spectroscopy (NIRS) is used to monitor brain and kidney perfusion in at-risk premature and term neonates. Although NIRS holds potential for bedside monitoring of intestinal perfusion, there is insufficient evidence showing correlation with mesenteric blood flow. To determine if an association exists between abdominal regional oxygen saturation (A-rSO(2)) and mesenteric blood flow, we compared changes in A-rSO(2) to changes in blood flow velocity in the superior mesenteric artery (SMA) before and after feedings in very-low birthweight infants. STUDY DESIGN: A-rSO(2) was continuously monitored midline below the umbilicus for 3 days in 18 stable 25 to 31 week bolus-fed infants (median BW 1203 g, median age 5 days). We compared change in SMA velocity from immediately before to 10 min and 60 to 120 min after feeding with change in A-rSO(2) over the same time. Spearman's rank correlation was used to ascertain if a significant association existed. RESULT: Change in A-rSO(2) was significantly associated with change in systolic, diastolic, and mean SMA velocity from fasting to 60 to 120min after feeding (P = 0.016, 0.021, 0.010) and from 10min after a feed to 60 to 120min after feeding (P = 0.009, 0.035, 0.032). CONCLUSION: In very preterm infants, A-rSO(2) reflects blood flow in the SMA and can provide non-invasive continuous monitoring of intestinal perfusion. Further studies are indicated to determine the sensitivity of NIRS to detect early intestinal pathology in this population.