TY - JOUR T1 - Symmetrical-Waveform High-Frequency Oscillation Increases Artificial Mucus Flow Without Changing Basal Mucus Transport in In Vitro Ovine Trachea JF - Respiratory Care SP - 435 LP - 441 DO - 10.4187/respcare.00809 VL - 56 IS - 4 AU - Stanislav Tatkov AU - Rodger J Pack Y1 - 2011/04/01 UR - http://rc.rcjournal.com/content/56/4/435.abstract N2 - BACKGROUND: The efficacy of symmetrical-waveform high-frequency oscillating (HFO) air flow for airway secretion clearance is controversial and debated in the literature. METHODS: We conducted in vitro experiments with ovine tracheae to investigate the effects of symmetrical-waveform HFO on tracheal transport of artificial mucus. We mounted each trachea as an intact tube, with a 15o head-down tilt, infused artificial mucus (10 mL over one hour) at the caudal end of the trachea, and measured mucus-transport velocity as the time between the beginning of infusion and the first appearance of artificial mucus over 2 near-infrared sensors at the rostral end of the trachea and by measuring the amount of mucus emerging. In a second series of experiments we opened each trachea flat and with video microscopy we measured the transport velocity of plaques over the endogenous mucus sheet. RESULTS: In the intact-trachea preparation, HFO at 20 Hz and 50 cm H2O increased mucus-transport velocity from 5.8 mm/min to 7.8 mm/min. HFO led to nearly half the artificial mucus being cleared during the infusion period. In the opened-trachea experiments the mean control transport velocity was 8.7 mm/min, and HFO, at 14 Hz or 20 Hz (and 50 cm H2O), did not significantly alter that velocity. CONCLUSIONS: Symmetrical-waveform HFO increases mucus-transport velocity and mucus clearance when a thick layer of mucus is present. This may be important when considering the mechanisms of mucus clearance and using HFO for secretion clearance. ER -