Resonance Raman Spectroscopy Tissue Oxygenation Measurements in Neonates

Introduction: Current oxygen monitoring by pulse oximetry has limitations and cannot provide estimates of the oxygen content in the microvasculature, where oxygen is used. Resonance Raman spectroscopy (RRS) provides noninvasive microvascular oxygen measurement. The objectives of this study were to (i) measure the correlation between preductal RRS microvascular oxygen saturations (RRS-StO2) and central venous oxygen saturation (SCVO2), (ii) develop normative data for RRS-StO2 measurements in healthy preterm infants, and (iii) determine the effect of blood transfusion on RRS-StO2. Methods: Thirty-three buccal and thenar RRS-StO2 measurements were performed in 26 subjects to correlate RRS-StO2 with SCVO2. Thirty-one measurements were performed in 28 subjects to develop normative RRS-StO2 values, and eight subjects were enrolled in the transfusion group to assess changes in RRS-StO2 with blood transfusion. Results: There were good correlations for buccal (r = 0.692) and thenar (r = 0.768) RRS-StO2 versus SCVO2. The median RRS-StO2 in healthy subjects was 76% (IQR 68.7–80.8). There was a significant increase of 7.8 ± 4.6% in the thenar RRS-StO2 after blood transfusion. Conclusions: RRS appears to be a safe and noninvasive means of monitoring microvascular oxygenation. Thenar RRS-StO2 measurements are more feasible and practical to use than buccal. In healthy preterm infants, the median RRS-StO2 was calculated based on measurements across various gestational age and gender. More studies evaluating the effects of gestational age of RRS-StO2 in various critical clinical settings are needed to confirm the findings.