260 - Correlation between near-infrared spectroscopy (NIRS) and lactate levels in neonates on coarctation watch: A prospective observational study

Publication Number: 4256.260

Margaret Christian, Hassenfeld Children's Hospital at NYU Langone, Jersey City, NJ, United States; Jaclyn McKinstry, NYU Langone Health, New York, NY, United States; Sean M. Bailey, Hassenfeld Children's Hospital at NYU Langone, New York, NY, United States; Erin Cicalese, New York University Grossman School of Medicine, New York, NY, United States

Background: Near-infrared spectroscopy (NIRS) measures regional oxygen saturation, which is indicative of tissue perfusion. Multiple centers have adopted NIRS in place of routine blood gases for neonates on arch watch. However, studies on the association between NIRS and lactate levels in neonates with concern for aortic coarctation are lacking.

Objective: Determine if there is a correlation between cerebral or renal tissue oxygen saturation measured by NIRS to lactate levels.

Design/Methods: This is an observational, prospective study. Neonates ≥34 weeks gestational age with concern for aortic coarctation were approached for enrollment. Exclusion criteria: cyanotic congenital heart disease, suspected/confirmed trisomy 13 / 18, hydrops.

NIRS sensors were placed on the forehead for cerebral monitoring and the flank for renal monitoring. Infants were monitored with routine blood gases per the institutional arch watch protocol. NIRS monitoring continued until coarct was ruled out or the infant underwent arch repair.

Correlation between lactate level and NIRS was analyzed by generating the line of best fit and determining the R-squared. Cerebral-to-renal oxygenation ratio (CROR) was calculated as the ratio of cerebral NIRS to corresponding renal NIRS. Correlation between lactate level and CROR was studied as above. Renal NIRS were compared across groups separated by lactate levels (ie lactate 0.5-1, 1-1.5 etc). T-test or Mann-Whitney U test was used to determine statistical significance based on whether the data followed a normal distribution.

Results: Included a total of 107 blood lactate samples with corresponding NIRS values from 4 neonates undergoing coarct watch. Cerebral NIRS (1) at time of lactate draw and (2) averaged over 2 / 5 / 10 minutes prior to lactate draw had a weak positive correlation with lactate levels [R2 = 0.05, 0.09, 0.1, 0.07 respectively]. Renal NIRS had a weak negative correlation with lactate levels [R2 = 0.02, 0.01, 0.01, 0.01 respectively]. CROR demonstrated a positive correlation with lactate level [R2 = 0.3]. Renal NIRS were significantly lower at lactate levels 3.5 - 4 as compared to 1.5 - 2 [NIRS at time of lactate draw: 33.5 ±16 vs 67 ± 9.7, p< 0.001; 2 minute average prior to lactate draw: 32.2 ± 16.7 vs 65.5 ± 8.4, p< 0.001; 5 minute average prior to lactate draw: 32.8 ± 15.6 vs 65.6 ± 7.4, p< 0.001].

Conclusion(s): There is a correlation with higher lactate levels corresponding to lower renal NIRS. This could safely allow for decreasing the frequency of blood draws during coarctation watch amongst neonates who are particularly susceptible to the physiologic effects of anemia.

Renal NIRS vs Lactate Group
Figure 1: Comparison of renal NIRS across lactate groups