Laboratory Evaluation of Four Different Devices for Secretion Mobilization: Acapella Choice, Green and Blue Versus Water Bottle

BACKGROUND: Secretion removal is a key issue in patients with respiratory diseases, and is
known to be most effective at vibration frequencies of 13 Hz and with the greatest amplitudes
possible. The Acapella devices and the water bottle are used for secretion removal in daily clinical
practice but without detailed knowledge on optimal settings. The aim of this study was to evaluate
the 3 different Acapella devices and the water bottle at various settings and flows to determine the
optimal devices and settings for effective secretion removal. METHODS: Three different Acapella
devices were tested at flows of 6, 12, 20, 30, 40, and 50 L/min, and at all 5 settings. The water bottle
was filled with 5, 10, or 15 cm of water, and tested at flows of 3, 6, 10, 12, and 20 L/min. For all
devices and combinations of settings, we measured the frequency and amplitude of the vibrations,
as well as the required pressure to generate vibrations. RESULTS: Setting 4 was the best for all 3
Acapella devices, and the filling height of the water bottle should be 5 cm. At these settings, all
devices elicited vibration frequencies between 12 and 15 Hz, which is theoretically optimal for
secretion mobilization. The resistance pressures of the devices to elicit these vibrations were between 5 and 11 cm H2O. However, the Acapella devices elicit higher vibration amplitudes (5– 8 cm
H2O) than the water bottle (1.8 cm H2O) CONCLUSIONS: Setting 4 was optimal for all 3 Acapella
devices. The Acapella devices may be more efficient for secretion mobilization than the water bottle,
because they elicit greater amplitude of vibrations. Key words: airway clearance therapy; bronchial
clearance; chest physiotherapy; evaluation of devices; mucus; oscillating positive expiratory pressure;
respiratory secretions