In Vitro Comparison of Aerosol Delivery in High-Frequency Assisted Airway Clearance Devices With Integrated Nebulizers

BACKGROUND: High-frequency assisted airway clearance systems combine positive expiratory pressure or oscillatory positive airway pressure with integrated nebulizers to improve the delivery of aerosols and assist with airway clearance. This aerosol study evaluated lung delivery efficiency during positive expiratory pressure and oscillatory positive airway pressure therapy of 2 high-frequency assisted airway clearance/nebulizer systems.

METHODS: Aerosol delivery was evaluated during positive expiratory pressure therapy of 10 cm H₂O and oscillatory positive airway pressure therapy of 20 cm H₂O with the BiWaze Clear and the Volara high-frequency assisted airway clearance/nebulizer systems. The handset and nebulizer were attached to an anatomic upper-airway model via a mouthpiece and placed into a plethysmograph. A tracheal filter was placed to capture the inhaled aerosol. A vacuum filter entrained fugitive aerosols from the plethysmograph. After nebulization of technetium in 3.0 mL normal saline solution, the components were scanned by using scintigraphy and the decay-corrected radiation counts were referenced to the initial nebulizer technetium charges.

RESULTS: Aerosol delivery during positive expiratory pressure therapy of 10 cm H₂O resulted in higher lung deposition with the BiWaze Clear versus the Volara (28 vs 6.2%; P < .001; 95% CI 16.5–27.7), and higher fugitive losses (23.7 vs 2.8%; P = .004) and nebulizer losses (55 vs 3.3%; P < .001) with the Volara than with the BiWaze Clear. Aerosol delivery during oscillatory positive airway pressure of 20 cm H₂O resulted in a higher lung deposition with the BiWaze Clear versus the Volara (16.3 vs 7.3%; P = .005; 95% CI 3.3–15) and higher fugitive (22.3 vs 3.8%; P = .02) and nebulizer (58.8 vs 7.2%; P = .004) losses with the Volara. There were no differences at the other locations during testing.

CONCLUSIONS: The BiWaze Clear system showed greater delivery efficiency than did the Volara during positive expiratory pressure and oscillatory positive airway pressure. The high residual nebulizer dose and fugitive aerosol losses through the handset leak valve contributed to the lower delivery efficiency observed with the Volara. The nebulizer type, circuit design, and handset are important factors when targeting effective aerosol delivery to the lungs with high-frequency assisted airway clearance therapy.