Chirurgia dróg oddechowych Syndrom brachycefaliczny – wprowadzenie

Pathophysiology of obstructive airway disease in the brachycephalic dog

The genesis of the brachycephalic syndrome is thought to be due to anatomic changes which lead to increased inspiratory resistance (Aron and Crowe 1985; Leonard 1957; Cook 1964; Hobson 1995; Koch 2003). In order to obtain sufficient oxygen, brachycephalic dogs must generate higher negative pressure. With significant negative pressure, the soft tissues are drawn into the lumen resulting in collapse of the upper airway (Thews 1983). Other manifestations of brachycephalic syndrome, such as everted laryngeal saccules, partial collapse of the dorsonasal pharynx, laryngeal collapse, and even collapse of other parts of the cartilaginous respiratory tract, obstruct the lumen even more. All these properties contribute to clinical signs and lead to further deterioration that may ultimately cause syncopal episodes and death from suffocation (Aron and Crowe 1985; Cook 1964).

It is known that the nose is the greatest source of flow resistance in the total airway system (Ohnishi and Ogura 1969), particularly in carnivorous species (Negus et al. 1970). Passage through the nasal cavities accounts for 76.5% of total airflow resistance whereas, in comparison, the larynx (4.5% of resistance) and the more distally situated trachea, bronchus, and bronchioli (19% of resistance) contribute only a modest amount.

While closed-mouth breathing, the nasal passage has to be overcome both during ins- and during expiration but only during inspiration while panting [...]

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