Aerosol Efficiency With Oscillatory Lung Expansion Systems

Abstract

Background:

Oscillatory lung expansion (OLE) therapy combines multiple airway clearance modalities, including positive expiratory pressure (PEP), high-frequency oscillations (OSC), and therapeutic aerosol delivery. This descriptive study in vitro aimed to evaluate aerosol drug delivery efficiency using gamma scintigraphy during simulated PEP and OSC therapy using the BiWaze Clear (ABM Respiratory) and Volara (Hillrom) OLE systems.

Methods:

We quantified regional deposition of inhaled aerosols to the upper airways, lungs, residual losses to the OLE system components, nebulizers and fugitive aerosol loss to the atmosphere with both PEP of 10 cm H₂O and OSC of 20 cm H₂O. A 3D printed adult upper airway cast was attached to a simulated trachea and adult lung model. A filter was attached between the tracheal outlet and the lung model to capture inhaled aerosols. The OLE handset, nebulizer, and mouthpiece were attached to the upper airway model and placed into a sealed plethysmograph. A vacuum filter placed on top of the plethysmograph was used to entrain fugitive aerosols. Each device was configured to nebulize 2.5 mL of saline labelled with Technetium (^99mTc) pertechnetate. Following nebulization, the different regions of interest were scanned for radiation counts and corrected for background radiation and decay.

Results:

The BiWaze Clear had a 5-fold greater delivered lung (filter) dose with PEP and 3-fold greater dose with OSC than the Volara (Figure). Depositional losses in the handset and mouthpiece were low. The residual nebulizer losses were high (>50%) with the Volara and low with BiWaze Clear (<7%). The depositional losses within the dual-lumen (closed) circuit/filter of BW Clear coincided with a lower concentration of fugitive aerosol released to the atmosphere than Volara. In contrast, the Volara had low deposition in the single-limb (open) circuit, with ∼1/3 of the nebulizer dose dispersed through the handset leak valve as a fugitive aerosol.

Conclusions:

These are the first studies in vitro to evaluate aerosol delivery with these novel OLE/aerosol systems. The major finding demonstrates high efficiency aerosol delivery (12-25%) with BiWaze Clear. We attribute these findings to the use of a vibrating mesh nebulizer, low nebulizer residual and the lack of an integrated leak in the nebulizer handset. In conclusion, some OLE systems may be capable of targeting sufficient pulmonary aerosol dosages during concurrent airway clearance therapy.