Endoscopic sensing of alveolar pH

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Pulmonary Physiology

Background:

• Accurate measurement of alveolar pH is crucial for understanding respiratory function and disease.
• Existing methods for alveolar pH measurement are limited or invasive.
• Novel sensing technologies are needed to advance pulmonary diagnostics.

Purpose of the Study:

• To develop and validate an endoscope-deployable optrode for real-time alveolar pH measurement.
• To demonstrate the capability of the system for multi-site pH sensing in an ex vivo lung model.
• To investigate the relationship between alveolar pH and mechanical ventilation.

Main Methods:

• Utilized functionalized gold nanoshell sensors with surface-enhanced Raman spectroscopy (SERS) for pH sensing.
• Designed an asymmetric dual-core optical fiber optrode to minimize fiber-generated Raman signals.
• Employed an ex vivo ovine lung model for testing the optrode's performance and accuracy.

Main Results:

• Achieved a ~100-fold increase in SERS signal-to-fiber background ratio.
• Demonstrated multi-site alveolar pH sensing with high accuracy (± 0.07 pH units).
• Successfully detected alveolar pH changes in response to ventilation parameters.

Conclusions:

• The endoscope-deployable optrode represents a significant advancement for in situ alveolar pH monitoring.
• This technology enables precise, real-time assessment of respiratory acini pH.
• The findings provide a new tool for studying lung physiology and the impact of ventilation on alveolar microenvironment.