Implications of mouth breathing on the pulmonary function and respiratory muscles

ABSTRACT The mouth breathing syndrome is characterized by a set of signs and symptoms, which may be present in subjects who replace the adequate and efficient nasal breathing mode by mouth or mixed breathing mode for more than six months. Mouth or mixed breathing mode may be associated to changes in the ventilatory function and mechanics. This review aims to further investigate the consequences of mouth breathing on the pulmonary function and respiratory muscles, emphasizing the development of such changes from childhood to adulthood. Eighteen articles were selected through PubMed and Web of Science databases and they were grouped in the text, covering the following topics:1) Implications of mouth breathing on the pulmonary function and 2)Implications of mouth breathing on the respiratory muscles. Based on the information from the articles analyzed, it can be noticed that a few studies rejected or did not find any relationship between pulmonary changes and mouth breathing. It is suggested that the muscular imbalance produced by these changes may contribute for the mechanical disadvantage of the diaphragm muscle and the increase of accessory inspiratory muscles work. Nevertheless, studies with more judicious methods, including objective and reproducible evaluation of the respiratory muscles are still needed.