Thermal Imaging as a Potential Diagnostic Tool of Nasal Airflow

Overview

Currently, there are no tools that can measure nasal airflow in an objective manner that is non-invasive to the patient. This clinical study aims to address this by evaluating the use of thermal imaging as a diagnostic tool for measuring nasal airflow. Proper airflow cools the nasal airway as it passes--obstructions or narrowed airways hinder flow and results in elevated temperatures along the airway and nasal tissue. It is this elevation in temperature, or more specifically, loss of cooling, that we hypothesize to be measurable with thermal imaging. Participants in this study will be asked to perform 3-4 nasal breathing cycles which will be recorded by the thermal imager.

Currently there's no non-invasive, objective method for measuring nasal airflow. The current standard, the NOSE score is an inaccurate measure of physiology (it is subjective). There is a considerable amount of data that demonstrates that the nasopharyngeal airway is the preferred ventilatory pathway for breathing at rest and during sleep. Finding a reliable measurement modality is important in light of this. The primary goal of this study is to evaluate a novel approach to measuring nasal airflow in thermal imaging. Previous studies show that higher temperatures of the nasal mucosa are related to decreased patency. The investigators hypothesize that reduced or obstructed airflow leads to the loss of the cooling oscillatory cycle present in normal nasal respiration. The investigators believe this diminished or absent cycle may be detectable via thermal imaging due to predicted elevation of mucosal temperatures (or loss of the cooling gradient). Other methods in the past aimed at measuring temperature changes introduced error due to their invasiveness (irritation of the mucosa lead to higher baseline oscillatory cycles). This is no longer an issue as the thermal imager requires no physical contact with the patient to function. There are several methods for measuring nasal patency that have been described throughout the literature. These include objective measurements such as acoustic rhinometry and rhinomanometry, as well as subjective measurements such as the Sino-Nasal Outcome Test and Nasal Obstruction Symptom Evaluation (NOSE) questionnaires. More recently, snap-on thermal imaging devices that take advantage of the processing power and high resolution of modern phones have surfaced leading to lower costs for highly-sensitive devices that we aim to use for measuring nasal airflow. The non-invasive nature of using thermal devices may lead to more accurate, objective measurements of nasal airflow as a previous study demonstrated that tactile irritation from other devices increase the mucosal temperature impeding measurement. (Bailey et al.). Other studies documented that improved sensation of nasal airflow is associated with cooler mucosal temperatures and that increased patency of the nasal passage is related to lower temperatures as well (and the opposite, decreased patency to increased temperatures). (Willatt et al.) We hypothesize that nasal airflow obstruction (NAO) leads to the loss of the cooling oscillatory cycle present in normal nasal respiration which we can detect via thermal imaging due to predicted elevation of mucosal temperatures.