265 - Resonance Raman Spectroscopy Reveals Tissue-Level Oxygenation Differences in Suspected Coarctation of the Aorta: A Pilot Neonatal Study

Publication Number: 4261.265

Alyssa R. Thomas, Brigham and Women's Hospital, SOUTH BOSTON, MA, United States; Lorelei Robinson, Geisel School of Medicine at Dartmouth, Hanover, NH, United States; Nancy Braudis, Boston Children's Hospital, Boston, MA, United States; Padraic Romfh, Pendar Medical, Cambridge, MA, United States; John Kheir, Boston Children's Hospital, BOSTON, MA, United States

Background: Coarctation of the aorta (CoA) can lead to life-threatening systemic hypoperfusion following ductal closure. Conventional screening via blood pressure and pulse oximetry gradients may miss evolving CoA. Resonance Raman spectroscopy (RRS) measures microvascular post-extraction oxy-hemoglobin saturation (RRS-ShbO₂) using vibrational spectroscopy and may be sensitive to evolving perfusion deficits in neonates with suspected CoA.

Objective: To assess the feasibility of non-invasive RRS monitoring and characterize peripheral tissue oxygenation patterns in infants with suspected CoA, stratified by surgical need.

Design/Methods: Pilot prospective study of infants admitted to the CICU due to pre- or post-natal concern for CoA. Study approved by IRB-P00044159. After parental consent, infants with suspected CoA underwent 15-min RRS measurements three times daily on the palm of the right hand (pre-ductal) and the sole of either foot (post-ductal). Pulse oximetry and blood pressure were recorded. Post-ductal ShbO₂ values and pre-post ductal (PPD) gradients were compared between infants who did and did not undergo surgery using Student's t-tests. A generalized estimating equation was used to model the association between ShbO₂ and surgery, accounting for repeated measures. ROC analysis using the lowest post-ductal ShbO₂ on/after DOL 3 identified the optimal diagnostic threshold by maximizing the Youden Index; sensitivity, specificity, and area under the curve were calculated.

Results: Fifteen infants were enrolled at a median of 1-day old (IQR 1-6); eight underwent neonatal CoA repair. RRS measurement was well tolerated with no adverse events. Mean post-ductal RRS-ShbO₂ was significantly lower in CoA infants: day 0-2 (non-CoA: 47% ± 19% vs. CoA: 24% ± 15%; p< 0.0001); day 3-5 (61% ±19% vs. 40% ±18%; p=0.0008) and day >5 (73% ±11% vs. 47% ±15%, p< 0.0001). RRS-ShbO₂ PPD gradients resolved by day 5 in the non-CoA group but persisted in CoA infants (day >5: 3% vs. 25%, p=0.0002). Across all days, a 10-point lower post-ductal RRS-ShbO₂ was associated with a 60% increase in the odds of CoA surgery (OR = 1.60; 95% CI: 1.17-2.20; p=0.005), independent of within-patient repeated measures. In a patient-level analysis, post-ductal RRS-ShbO₂ < 39% on day ≥3 identified all infants who underwent coarctation surgery (100% sensitivity) with 80% specificity (AUC=0.83).

Conclusion(s): Persistent post-ductal desaturation in CoA infants as detected by RRS reflects evolving arch obstruction, altered perfusion, and right-to-left ductal shunting. RRS offers a feasible, non-invasive, real-time adjunct to assess impaired perfusion.

Figure 1. Infant with suspected coarctation of the aorta (CoA) with RRS probes in place
Figure 1. Illustration of infant with RRS probes in place on superficial skin of right palm and sole of foot, showing example pre- and post-ductal RRS values with ductal restriction in the setting of an evolving CoA.

Figure 2. RRS-ShbO₂ by day of life
Figure 2A: Mean foot (post-ductal) RRS-ShbO₂ by day of life (DOL) in newborns who did not undergo surgery (non-CoA; yellow) or did undergo surgery (CoA; red). 2B: Pre- (hand) -post-ductal (foot) ShbO₂ gradients by DOL in non-CoA versus CoA group.

Figure 3. ROC Curve
Figure 3. ROC curve showing the predictive performance of patient-level lowest post-ductal (foot) RRS-ShbO₂ on or after day 3 of life for CoA surgery in infants undergoing monitoring for evolving arch obstruction. The threshold of post-ductal RRS-ShbO₂ <39% identified all infants who underwent surgery with 100% sensitivity and 80% specificity (AUC = 0.83).