A comparison of two methods for determining nasal irritant sensitivity

Area of Science:

• Environmental Health
• Respiratory Physiology
• Sensory Science

Background:

• Nasal irritation from air pollution causes significant symptoms like rhinorrhea and congestion.
• Individual sensitivity to nasal irritants varies, but a standardized clinical index is lacking.
• Objective measures are needed to quantify nasal irritant sensitivity.

Purpose of the Study:

• To compare two objective methods for assessing nasal irritant sensitivity: CO2 detection and CO2-induced respiratory pattern disruption.
• To determine the more reliable and clinically applicable method for measuring individual nasal irritant sensitivity.

Main Methods:

• Twenty healthy adults were exposed to varying concentrations of carbon dioxide (CO2) via nasal cannula.
• Two methods were used: a CO2 detection task and monitoring respiratory pattern changes using a flow thermocouple.
• CO2 pulses were synchronized with the inspiratory phase and presented alongside filtered air.

Main Results:

• All subjects could detect CO2, establishing CO2 detection thresholds.
• Only 65% of subjects showed CO2-induced respiratory pattern disruption, which was inconsistently observed.
• CO2 detection thresholds proved to be a more objective and reproducible measure of nasal irritant sensitivity.

Conclusions:

• Carbon dioxide detection threshold is a more objective and consistently applicable endpoint for assessing individual nasal irritant sensitivity.
• This method holds promise for clinical use in evaluating responses to air pollutants.
• Further research may refine the use of respiratory pattern disruption but CO2 detection is currently superior.