A Distinct Difference Between Air and Mucosal Temperatures in Human Respiratory Tract

Area of Science:

• Respiratory physiology
• Thermophysiology

Background:

• Temperature-sensitive ion channels in airway sensory nerves are well-documented.
• Airway temperature influences respiratory functions, but direct mucosal measurements are lacking.

Purpose of the Study:

• To directly measure airway mucosal temperature during the respiratory cycle.
• To investigate the accuracy of peak exhaled breath temperature (PEBT) as an indicator of airway tissue temperature.

Main Methods:

• Utilized a miniature, rapid-response temperature probe for direct mucosal temperature measurements.
• Measured temperatures in the trachea, major, lobar, and segmental bronchi during bronchoscopy in eight human subjects.

Main Results:

• Airway mucosal temperature was stable and did not fluctuate with respiration.
• Mucosal temperature increased progressively from the trachea to segmental bronchi (35.7°C to 36.9°C).
• Directly measured mucosal temperatures were significantly higher than PEBT (31.7°C).

Conclusions:

• Airway mucosal temperature is distinct from exhaled breath temperature.
• PEBT is an inaccurate proxy for airway tissue temperature due to thermal conductivity differences.
• Understanding this temperature discrepancy is vital for accurate clinical diagnosis of airway inflammation.