Tissue oxygenation monitoring using resonance Raman spectroscopy during hemorrhage

Abstract

RRS-StO2 seems to have significantly better ability to track central oxygenation measures during hemorrhage as well as to predict shock based on elevated lactate levels when compared with NIRS-StO2.

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

“…In the future, variations in RRS measurements in both these populations should be investigated in the context of cardiac hemodynamics specifically with relation to a patent ductus arteriosus, which may explain day-to-day changes seen in the RRS measurements. It is also unclear whether the buccal mucosa is an appropriate monitoring site, as it required the investigator to manually maintain the probe in place for all measurements, and differences in buccal vascular orientation exist compared to limb circulation [11,25]. We also did not investigate the effect of heating the plantar surface of premature neonates on RRS measurements.…”

“…The scattered light was captured in the charged-coupled spectrometer each second, producing different spectral peaks linearly proportional to oxy- and deoxyhemoglobin concentrations. These peaks were converted to a ratio of oxyhemoglobin to total hemoglobin by averaging data from 20 to 180 individual spectra [11,17,18,19]. The first 5 min of data were excluded to allow skin surface adequate time to “auto-fluoresce” to diminish signal-to-noise ratio.…”

“…This produces distinct spectral peaks that are converted to a ratio of oxyhemoglobin to total hemoglobin. RRS correlates better with serum indicators of tissue health (ScvO 2 and lactate) compared to NIRS in an animal hemorrhage model [11]. In this pilot study, we examined the feasibility of measuring RRS tissue oxygenation (RRS-StO 2 ) and generated descriptive data within gender and racial sub-groups of neonates.…”

“…While some NIRS sensors, designed to measure cerebral, renal, and splanchnic tissue oxygenation, are convenient, others are cumbersome when applied to a neonate, making prolonged monitoring challenging [7,8,9,10]. Additionally, the NIRS spectra of myoglobin are indistinguishable from that of oxy- and deoxyhemoglobin, which might account for the majority of the NIRS signal based on proton magnetic resonance data [11,12,13]. Additional optical methods used to assess peripheral perfusion include perfusion index, laser Doppler flowmetry, orthogonal polarization spectroscopy, and resonance Raman spectroscopy (RRS).…”

“…Additional optical methods used to assess peripheral perfusion include perfusion index, laser Doppler flowmetry, orthogonal polarization spectroscopy, and resonance Raman spectroscopy (RRS). RRS is a technology that has been studied primarily in animals and adults to monitor peripheral tissue oxygenation [11,14,15,16]. The spectroscopic basis lies in the concentration-dependent vibrational enhancement of oxy- and deoxyhemoglobin in the deep-violet wavelength region (∼400 nm).…”