High-frequency ventilation does not affect pulmonary surfactant, liquid, or morphologic features in normal cats.

Effects on pulmonary surfactant, liquid, and morphologic features were compared in normal cats ventilated with conventional and high-frequency ventilators for 4 h. Normal blood gases and comparable mean airway pressures (approximately 7 cm H2O) were maintained with the two techniques. Peak tracheal pressure during conventional ventilation (16.5 +/- 0.9 cm H2O) was significantly greater than that during high-frequency ventilation (8.5 +/- 1.1 cm H2O, p less than 0.00001). Pressure-volume curves were identical in control, conventional, and high-frequency ventilation groups. There was no effect on pulmonary lavage surfactant, whether measured functionally or biochemically. Likewise, lung liquid and morphologic aspects examined by both light and electron microscopy were not affected. These results provide evidence that high-frequency ventilation under these conditions does not cause pulmonary damage.