Physiology of the Nasal Cartilages and Their Importance to Rhinosurgery

Cyclic congestion and decongestion in the two nasal cavities is seen in connection with the respiratory function of the nose. The turbulent behavior of nasal airflow is a prerequisite for adequate contact of inspired air particles with the mucosa. The aim of this study was to gain insight into this turbulent behavior of nasal airflow during the nasal cycle. The nasal cycle in 10 healthy human subjects was investigated using endoscopic imaging, rhinoresistometry, and acoustic rhinometry every 20 minutes over a time period of up to 15 hours. The following parameters were recorded for each nasal cavity: airflow resistance, hydraulic diameter, friction coefficient lambda as an indicator for the wall configuration triggering turbulence, transition from laminar to turbulent flow, and the minimal cross-sectional areas. In addition to the known cyclic change of flow resistance and nasal width, a periodic change in the turbulence behavior was observed. In the resting phase, mainly laminar flow was found. During the working phase, the onset of turbulence occurred already at low flow velocities. The increase of turbulence during the working phase is caused by the increase in cross-sectional area in the anterior cavum due to decongestion of the mucosa of the head of the inferior turbinate and the septal tuberculum. Rhinoresistometry and acoustic rhinometry complement each other. The combination of the two methods provides insight into the functional changes during the nasal cycle and into nasal physiology in general. The authors therefore advocate a combination of the two methods for functional evaluation of the nasal airway.

This study was performed to determine the various processes involved in the behaviour of hyaline cartilage during the wound healing period after trauma or surgery of vulnerable structures like the nasal septal cartilage and the cricoid. The results of different procedures (perpendicular and parallel to the cartilage surface) in young and young-adult animals were analyzed: septal incision at different locations (young-old), cricoid split (young-old), suturing cartilage, closing defects with autologous cartilage (young), biomaterials (young) and newly engineered cartilage in 4- and 24-week-old rabbits (series of ten animals). Cartilage of the young rabbit and child have similar hyaline cartilage with a varying distribution in thickness. Thinner areas are more susceptible to malformations. Incisions through younger cartilage give rise to some new cartilage formation covered by a new layer of perichondrium: through older, differentiated cartilage the incision causes superficial but permanent necrosis. Edges of cut cartilage mostly do heal by formation of fibrous junctions. This forms a weak spot, sensitive to deviations. The same fate goes for the healing between the autologous graft and the surrounding pre-existent cartilage. Trauma parallel to the surface, leads to inconsistent quantity of neocartilage. With ageing the wound healing and regenerative capacities decrease. In general, biomaterials are less accepted by the surrounding tissues and would impede further growth. Only newly engineered, and thus less differentiated (younger) cartilage of hyaline nature, appeared to be well accepted at the interface with the edges of a cartilage defect. There are indications that the release of growth factors might play a role in cartilage wound healing. In the child as well as the adult, wound healing of hyaline cartilage structures is incomplete, and surgery remains 'experimental' surgery. The clinical implications of gradual loss of the regenerative capacity of hyaline cartilage should be further investigated.