RESUMO
Abstract Objectives: To analyze breathing modes with infrared thermography. Methods: Cross-sectional observational exploratory study conducted in 20 female participants with a mean age of 26.0-years. The thermograms were made following the principles of the American Academy of Thermology and the Brazilian Thermology Society. The camera FLIR A315 (FLIR Inc., Santa Barbara, CA) was used for the tests. The recordings consisted of the participants breathing normally through the nose for 2 min and simulating oral/oronasal breathing for another 2min. The thermograms were analyzed with the FLIR Tools software. An ellipse was placed between the nostrils and the lip commissures to obtain the mean temperatures. The collection was made by two independent researchers, and the normalized non-dimensional temperature was calculated. Results: The temperature in nasal breathing is higher than in oral/oronasal breathing both for inhaling and exhaling when measured in the region of the mouth. The exhaling temperatures were higher than the inhaling ones in oral/oronasal breathing (through the nose and the mouth) and nasal breathing (only through the nose). The temperature difference between exhaling and inhaling (ΔT) was greater in oral/oronasal breathing when measured in the region of the mouth. Conclusion: The thermographic assessment of breathing modes may be made by comparing the mean temperatures of the mouth, using an ellipse. Level of evidence: Study without consistently applied reference standards.