Transport of pulmonary secretions by asymmetric high frequency oscillation

Asymmetric high frequency oscillation (AHFO) was investigated as a mechanism for augmenting the clearance of excess pulmonary secretions from the airways of the lungs. In vitro and in vivo models were developed to test its ability to predictably transport pulmonary secretions. The augmentation of mucus transport by 10 Hz AHFO was investigated in the canine trachea. Ventilation of eight dogs (2 studies each) was performed with three AHFO power settings in random order and conventional mechanical ventilation (CMV) before or after the AHFO trials. Prior to each trial, 35-45 μl of canine muscus mixed with a radiotagged colloid (99Tc/sup m/) was instilled in the distal trachea. As the radiotagged mixture traveled up the trachea, tracheal muscus velocities (TMV) were recorded on six channels with a multidetector probe. CMV mean TMVs before and after AHFO were not significantly different. The mean TMV of 6.3 +/- 2.6 mm/min at 30% power AHFO was faster than the CMV mean TVM of 4.1 +/- 2.1 mm/min (p <0.05)