Passive Upper Airway Thermoregulation and High-Speed Assessment for Conventional versus Menthol Cigarette: Implications for Laryngeal Physiology

Abstract

Purpose: This investigation combined measures of upper airway temperature (UAT) with high-speed laryngeal imaging in an individual who smoked a filtered conventional and menthol cigarette to identify laryngeal vibratory differences with upper airway temperature change. It was hypothesized that (1) average UAT differences between trials would be similar with UAT change ≤2°C and (2) high-speed parameters would not differ between trials. Method: In a repeated measures design, UAT was measured continuously during smoking. High-speed laryngeal imaging was conducted immediately after each smoking trial and 10 minutes post. Results: Average UAT and end-inspiratory temperature during the menthol trial was unexpectedly low. Immediately following both trials, there was an increase in phase asymmetry, vibratory amplitude (greater magnitude of change for the nonmenthol trial), and the opening phase of the glottal cycle and a decrease in fundamental frequency compared to the baseline. During recovery, parameters returned to the baseline for the nonmenthol trial, however, fundamental frequency continued to be lower and vibratory amplitude continued to be larger at recovery for the menthol trial. The measure of oscillatory onset time did not change across the trials immediately post cigarette trial and during recovery suggesting that smoking resulted in changes in sustained vibratory function rather than the onset behavior. Conclusions: Preliminary findings suggest that continuous thermal mapping and high-speed laryngeal function assessment may provide new information about the manner in which laryngeal tissue responds to passive thermal perturbations with direct implications for laryngeal epithelial and skeletal muscle function. Future large-scale studies are needed to investigate this in detail.