TY - JOUR T1 - Tracheal mucus clearance in high-frequency oscillation: effect of peak flow rate bias JF - European Respiratory Journal JO - Eur Respir J SP - 6 LP - 13 DO - 10.1183/09031936.93.03010006 VL - 3 IS - 1 AU - M King AU - A Zidulka AU - DM Phillips AU - D Wight AU - D Gross AU - HK Chang Y1 - 1990/01/01 UR - http://erj.ersjournals.com/content/3/1/6.abstract N2 - We have reported previously that high-frequency oscillation of the chest wall (HFO/CW) enhances the tracheal mucus clearance rate (TMCR) in dogs. This enhancement of TMCR may be due in part to the expiratory bias in peak flow rate (VE/VI greater than 1) that occurs during HFO/CW. We examined this factor in 8 anaesthetized, spontaneously breathing dogs by comparing TMCR during the following manoeuvers: 1) HFO/CW, applied by means of a thoracic cuff; 2) symmetric high-frequency oscillation via the airway opening (HFO/AO), applied by means of a piston pump driven by sinusoidal signal; 3) HFO/AO with an expiratory bias in peak flow, and 4) HFO/AO with an inspiratory bias in peak flow. All manoeuvers were of 5 min duration and were performed at 13 Hz and an oscillatory tidal volume of 1.5 ml.kg-1. In the latter two manoeuvers, the piston pump was driven by a nonsinusoidal signal such that peak VE/VI was greater than and less than unity, respectively. A high-impedance, cross-current flow of warmed, humidified air was provided at the tracheal tube. The order of manoeuvers 2, 3 and 4 was randomized, while manoeuver 1 was repeated at the end. TMCR was determined by direct bronchoscopic visualization of charcoal particle transport. Each HFO manoeuver was bracketed by a control period of spontaneous breathing. We found that TMCR during HFO/CW was 2.4 x control (p less than 0.001), in line with previous results.(ABSTRACT TRUNCATED AT 250 WORDS) ER -