Increases in total respiratory resistance during forehead temperature stimulation

Area of Science:

• Physiology
• Respiratory System Mechanics

Background:

• Understanding the physiological responses to thermal stimulation is crucial for respiratory research.
• Forehead temperature changes can influence autonomic nervous system activity and respiratory control.

Purpose of the Study:

• To investigate the effects of moderate forehead temperature stimulation on total respiratory resistance.
• To examine the time course, stability, and influencing factors of these respiratory changes.

Main Methods:

• Two experiments with 38 healthy participants involved applying moderate (20-23°C) and cold (8-11°C) water bags to the forehead for 60 seconds.
• Continuous measurements included oscillatory resistance (R(os)), heart period (HP), respiratory sinus arrhythmia (RSA), and ventilatory parameters.

Main Results:

• Moderate forehead temperature stimulation induced phasic increases in R(os), particularly during the initial 20 seconds, which were replicated across trials.
• These increases were mainly attributed to the inspiratory component, suggesting minimal upper airway artifact contribution.
• Heart period (HP) showed the most significant increase, while respiratory sinus arrhythmia (RSA) did not change significantly. Ventilatory adjustments did not mediate the R(os) increases.

Conclusions:

• Forehead temperature stimulation can transiently alter respiratory resistance in healthy individuals.
• The observed changes are primarily linked to the inspiratory phase and accompanied by significant cardiac autonomic adjustments (increased HP).
• Individual responses exhibit moderate within-session stability, indicating potential for personalized physiological assessments.