Direct Measurement of Tissue Oxygenation in Neonates via Resonance Raman Spectroscopy: A Pilot Study

Abstract

Background: The ability to monitor tissue oxygenation in neonates remains a challenge due to limited blood supply and the reliance on invasive procedures. Resonance Raman spectroscopy noninvasively measures tissue oxygenation (RRS-StO₂). Peripheral tissue oxygenation using this novel technology has not been described in neonates. Objectives: To examine the relationship between short-term RRS-StO₂ measurements and central venous saturation (ScvO₂) and pulse oximetry (SpO₂) in preterm and term neonates. Methods: Ninety-seven term neonates had buccal and plantar RRS-StO₂ measurements performed. In 15 preterm neonates, similar measurements were obtained in conjunction with ScvO₂ in the first week of life. Simultaneous SpO₂ and heart rate were also recorded. Results: In healthy neonates, buccal RRS-StO₂ values negatively correlated with the day of life. No correlation existed between buccal and plantar RRS-StO₂ values and ScvO₂ or SpO₂. Greater intra-patient plantar RRS-StO₂ variability was seen in preterm neonates with increasing respiratory support. Conclusions: Neonatal RRS-StO₂ measurements are feasible short term but do not correlate with ScvO₂ and SpO₂. Healthy neonates had greater differences and variability in RRS-StO₂ values, illustrating an evolving microcirculation not detected with pulse oximetry. Greater RRS-StO₂ variability in sick neonates requiring respiratory support may indicate microcirculatory instability despite being within target SpO₂ ranges. Further study is needed to establish if RRS-StO₂ monitoring is an accurate representation of tissue oxygenation.

Resonance Raman Spectroscopy Tissue Oxygenation Measurements in Neonates

“…In their study, it was on the bottom of a warmed left foot with data collected for 10 min, whereas in our study, the measurement was done closer to the heart, at a preductal site and for at least three times as long. In Iyengar et al [15] study, the RRS-StO2 in other stable preterm infants receiving various buccal RRS-StO2 respiratory support (74.2%) was very similar to the median value for a mixed population of healthy newborns (75.6%) in our study. Preterm infants receive one or more RBC transfusions during their stay in the neonatal intensive care unit that can be associated with increase in morbidity and mortality [22,23].…”

“…There are a limited number of studies carried out in healthy adults, and these showed that the average S CV O 2 ranged from 75 to 76.8% [20,21]. In another study in neonates, Iyengar et al [15] found that in full-term infants, the average RRS-StO2 was 88.4% at the buccal site and 52.7% at the plantar surface. The difference between their peripheral measurement and ours may be due to the placement of the probe.…”

“…Recently, RRS applied in adults showed a good correlation of RRS-StO2 measured in the buccal mucosa against S CV O 2 [14]. A similar study carried out in newborns to correlate S CV O 2 with RRS-StO2 in the lower extremity did not find a correlation [15].…”

“…At each site, values were recorded every second while the probe was in place. A picture with the thenar probe placed has been published before [15].…”

Monitoring of blood oxygenation in brain by resonance Raman spectroscopy

“…Tiba et al demonstrated that RRS tracks the central venous Hb oxygenation under hemorrhage in the buccal mucosa of swine better, than NIRS . Iyengar et al used RRS to monitor tissue oxygenation in neonates . Authors of all detailed in vivo RRS‐based studies of blood oxygenation used laser excitation at 405 to 407 nm.…”