Physiology and Pathophysiology of Nasal Breathing
The respiratory function of the nose is to warm, humidify, and clean the inhaled air. The basic condition for that is an undisturbed nasal air passage. The physical knowledge to understand the different causes for an increased nasal resistance is reported
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Gunter H. Mlynski
Keywords
Respiratory function • Nasal airflow • Nasal functional architecture • Nasal resistance • Flow behavior • Turbulence regulation • Nasal cycle • Rhinosurgery
Core Messages
• Normal respiratory function in the nose requires low physiological nasal airflow resistance and adequate contact between the air and a large mucosal surface in a narrow flow channel. • Narrowing of the nasal airways and/or severe turbulence can cause a pathological rise in nasal resistance. • Since resistance to flow rises exponentially with increasing stenosis, even slight narrowing in the area of the isthmus can lead to severe nasal obstruction. This fact is often overlooked. • In terms of respiratory function, the nasal flow channel can be divided into an inflow area, a functional area, and an outflow area.
G.H. Mlynski, PhD Department of Otorhinolaryngology, Head and Neck Surgery, University of Greifswald, Walter-Rathenaustr. 43–45, D–17475, Greifswald, Germany e-mail: [email protected]
• In the inspiratory flow direction, the inflow area consists of the vestibulum, the isthmus, and the anterior cavum. After passing over the head of the inferior turbinate and the septum in the anterior cavum, the airstream is directed to the turbinate region and distributed over its entire cross-sectional surface and the degree of turbulence is regulated. • In the functional area, the nasal turbinates not only represent a large surface, but through their adaptation in shape and size, they also create a uniform slit space between the septum and the lateral wall of the cavum, which promotes warming, humidification, and cleansing of the inspired air. • The inspiratory outflow area consists of the nasopharyngeal meatus, the choanae, and the nasopharynx. Here the airflow becomes increasingly laminar and is redirected in the direction of the deeper air passages. • A large thermal energy and humidity gradient is required between the mucosa
T.M. Önerci (ed.), Nasal Physiology and Pathophysiology of Nasal Disorders, DOI 10.1007/978-3-642-37250-6_20, © Springer-Verlag Berlin Heidelberg 2013
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and the airstream for effective warming and humidification of the air in the nose. These conditions are assured by the nasal cycle. • The division of the nose into two sides by the septum makes it possible to alternate between working and resting phases to improve gradients of thermal energy and humidity. • The nasal septum is rarely straight within the generally asymmetrical human skull. By means of a “physiological deviation” of the septum and adaptation of the configuration of the turbinates, a symmetrical slit space results on each side of the nose. Cyclical congestion of the turbinates makes it possible to have adequate working and resting phases. • Adopting a more physiologically sophisticated perspective in functional rhinosurgery leads to the result that: – Physiological septal deviations would not be straightened. – Pathological septal deviations would not be fully straightened, but instead transformed into p
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