Buffered end-tidal (BET) sampling-a novel method for real-time breath-gas analysis

Area of Science:

• Analytical Chemistry
• Respiratory Physiology

Background:

• Real-time breath-gas analysis is crucial for diagnostics.
• Conventional direct on-line sampling has limitations, including short sampling times and potential for hyperventilation.

Purpose of the Study:

• To introduce and validate a novel buffered end-tidal (BET) on-line sampling method for mass-spectrometric breath-gas analysis.
• To compare BET sampling with direct on-line sampling.

Main Methods:

• Developed a tailored tube for buffering the end-tidal fraction of breath-gas during exhalation.
• Employed proton-transfer-reaction mass spectrometry (PTR-MS) for comparative measurements.
• Collected breath samples using both BET and direct on-line sampling techniques.

Main Results:

• BET sampling significantly increased sampling time (to several seconds) and improved signal quality.
• BET sampling requires only one exhalation per minute, allowing normal breathing patterns and reducing hyperventilation risk.
• Excellent agreement was found for acetone and acetonitrile concentrations between BET and direct sampling.
• High variability in isoprene concentrations was observed, attributed to exhalation depth and hyperventilation effects.

Conclusions:

• The buffered end-tidal (BET) on-line sampling method offers a robust and efficient approach for real-time breath-gas analysis.
• BET sampling enhances data quality and subject comfort compared to direct on-line methods.
• Further investigation is needed to address variability in specific biomarkers like isoprene.