(26) Evaluating the association of hemoglobin and kidney oxygenation in preterm neonates

Background: Decreased kidney oxygenation, as measured by near infrared spectroscopy (NIRS), is associated with development of acute kidney injury (AKI) in premature neonates. Due to high oxygen demands of the kidney, it is possible that low hemoglobin could lead to significantly decreased kidney oxygenation and subsequent injury. Given the high rates of anemia in preterm neonates born < 32 weeks’ gestational age (GA), we sought to establish the relationship between hemoglobin levels and kidney oxygenation.

Objectives: To determine the association between hemoglobin and kidney oxygenation in neonates < 32 weeks of GA.

Design/Methods: A prospective observational study of preterm neonates born at < 32 weeks GA monitored with Invos NIRS neonatal sensors was performed from 2021-2023. All participants received standard of care continuous NIRS monitoring typically beginning within 96 hours of birth and lasting until the neonate (1) no longer required intravenous fluids or medications, (2) was on fully fortified feedings, and (3) did not have hemodynamically significant patent ductus arteriosus. Hemoglobins were measured at the discretion of the medical team. The association between mean hemoglobin and mean kidney oxygenation within the first 14 days of age was analyzed. Spearman’s rank coefficient was calculated to measure the strength and direction of association.

Results: Of 95 neonates evaluated, 93 were included for analysis (2 excluded for missing data). The mean birthweight was 1242 g and mean GA 28.3 weeks (Table 1, Demographics). The range of number of hemoglobin measurements was 1-9 with a median of 2 per neonate and mean hemoglobin concentration (standard deviation) of 15.5 g/dL (SD 2.5). The median number of hours of kidney oxygenation monitoring was 211 hours. The mean kidney oxygenation was 64.2% (SD 9.4, Figure 1). A significant correlation between mean hemoglobin and mean kidney oxygenation was found (Spearman’s correlation = 0.60, p < 0.01, Figure 2). There was also a significant correlation between GA and both hemoglobin and kidney oxygenation (Spearman’s correlation = 0.40 and 0.50 respectively, p < 0.01, Figure 3).

Conclusion: In preterm neonates, decreased hemoglobin correlates with decreased kidney oxygenation. Further research is necessary to determine if early management of neonatal anemia improves kidney oxygenation and decreases the risk of AKI.