Brain tissue oxygen evaluation by wireless near-infrared spectroscopy

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Devices

Background:

• Monitoring partial pressure of oxygen in brain tissue (PbtO2) is crucial for traumatic brain injury (TBI) management but is invasive.
• Near-infrared spectroscopy (NIRS) offers a noninvasive method to assess cerebral ischemia and hypoxia by monitoring hemoglobin parameters.
• NIRS shows potential for noninvasively estimating PbtO2 changes in TBI.

Purpose of the Study:

• To develop and evaluate a novel wireless NIRS system for monitoring rat brain hemoglobin parameters during TBI.
• To investigate the correlation between NIRS-derived hemoglobin changes and PbtO2 under varying TBI impact strengths.
• To assess the potential of NIRS as a noninvasive tool for estimating PbtO2 in TBI.

Main Methods:

• A wireless NIRS system and a PbtO2 monitoring system were employed in rats subjected to different TBI impact strengths (sham, 1.6, 2.0, 2.4 atm).
• Changes in oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), and total hemoglobin (HbT) were measured and correlated with PbtO2.
• Triphenyltetrazolium chloride (TTC) staining was used to determine infarction volume.

Main Results:

• Hemoglobin parameters (HbO2, HbR, HbT) and PbtO2 exhibited similar trends, decreasing post-impact and then stabilizing.
• A significant positive correlation was found between changes in PbtO2 and HbO2 (correlation = 0.76), but not with HbR (correlation = 0.06).
• Infarction volume showed a strong negative association with PbtO2 and HbO2.

Conclusions:

• Changes in HbO2 measured by NIRS are highly correlated with PbtO2 changes in TBI.
• The developed wireless NIRS system shows promise as a noninvasive method for estimating PbtO2 in brain tissue after TBI.
• Relative changes in HbO2 can serve as a reference parameter for noninvasive PbtO2 estimation in TBI.