Effect of combined high-frequency oscillatory ventilation on rabbit alveolar type-2 cells.

The effects on lung tissue of high-frequency oscillatory ventilation combined with intermittent mandatory ventilation (HFO-IMV) were compared with those of conventional mechanical ventilation (CMV) by matching the mean tracheal pressure. Pulmonary alveolar type-2 cells and subcellular organelles from rabbit lung were morphometrically examined by electron microscopy. The volume and surface densities of lamellar bodies in alveolar type-2 cells from the animals ventilated with HFO-IMV were decreased significantly compared with those from the animals either ventilated with CMV or breathing spontaneously (control group). The cell surface to volume ratio in the HFO-IMV group showed a significant increase compared with the CMV groups, whereas other variables showed no differences between the three groups. These results suggest that the secretion of surfactant from alveolar type-2 cells was enhanced in HFO-IMV-treated animals compared with CMV-treated and control groups.