Air sac cannulas are indicated in birds with upper respiratory obstruction or for ventilation during surgical procedures involving the head and neck. Proper technique, knowledge of potential ...

THIN-WALLED expansions of the tracheæ known as air sacs occur in those insects which have well-developed powers of flight. Misconception as to the function of these structures is common.

Because the Sacramento Valley is shaped like a bowl, smog presents a critical problem in the summer, when an inversion layer traps pollutants close to the ground, causing unhealthy air quality levels.