Tissue oxygenation monitoring using resonance Raman spectroscopy during hemorrhage

Area of Science:

• Biomedical Engineering
• Medical Physics
• Critical Care Medicine

Background:

• Noninvasive monitoring of patient hemorrhage remains a significant clinical challenge.
• Assessing tissue hemoglobin oxygenation is crucial for managing hemorrhagic shock.
• Conventional invasive methods for monitoring oxygen saturation have limitations.

Purpose of the Study:

• To evaluate the efficacy of resonance Raman spectroscopy for tissue oxygenation (RRS-StO2) in monitoring hemorrhage.
• To compare RRS-StO2 performance against invasive mixed venous (SmvO2) and central venous (ScvO2) oxygen saturation.
• To compare RRS-StO2 with near-infrared spectroscopy tissue oxygenation (NIRS-StO2) in a hemorrhage model.

Main Methods:

• Hemorrhage was induced in five swine at 30 mL/min for 60 minutes.
• RRS-StO2 was continuously measured from the buccal mucosa; NIRS-StO2 from the forelimb.
• Paired invasive measurements of SmvO2, ScvO2, and lactate were collected, with ROC analysis for predictive performance.

Main Results:

• RRS-StO2 changes closely tracked SmvO2 (r=0.917) and ScvO2 (r=0.901) during hemorrhage.
• NIRS-StO2 showed poor correlation with SmvO2 (r=0.283) and ScvO2 (r=0.142).
• ROC analysis revealed superior performance for RRS-StO2 (0.972) compared to NIRS-StO2 (0.611) in predicting elevated lactate levels.

Conclusions:

• RRS-StO2 demonstrates a significantly better ability to track central oxygenation measures during hemorrhage.
• RRS-StO2 outperforms NIRS-StO2 in predicting shock based on elevated lactate levels.
• RRS-StO2 shows promise as a noninvasive tool for monitoring patients during hemorrhage.