• Michael C Quong, Bernard Thébaud, and Warren H Finlay.
• Department of Electrical and Computer Engineering, University of Alberta, 9107 116 Street, Edmonton, Alberta T6G2V4 Canada. mquong@ualberta.ca
• Resp Care. 2006 Nov 1; 51 (11): 1244-50.

BackgroundA substantial percentage of the aerosol produced by a nebulizer is lost down the expiratory limb of the ventilator circuit. We describe a method for the capture, return, and re-aerosolization of that undelivered aerosol.MethodsWe designed an expiratory-limb setup in which an "entraining jet" of gas accelerates unused aerosol and propels it toward an impaction surface. The deposited solution is then returned to the nebulizer reservoir via a feedback tube. As a result, more of the initial dose is delivered to the patient. The fraction of the dose delivered to a filter connected to a passive neonatal test lung was measured with and without the aerosol-recycling components activated. We used a deltaP (difference between the peak inspiratory pressure and the positive-end-expiratory pressure) of approximately 7.5 cm H2O, tidal volume of approximately 6 mL, respiratory rate of 40 breaths/min, and an inspiratory-expiratory ratio of 1:2.3.ResultsThere was a statistically significant improvement with the feedback return to the reservoir, with up to nearly 60% more aerosol delivered.ConclusionThis improvement in aerosol delivery is encouraging, but more comprehensive studies are needed before such a device could be implemented clinically.

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