A method for increasing jet nebulizer delivery efficiency for aerosol drug delivery in ventilated newborns: an in vitro study.
BACKGROUND
A 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.


METHODS
We 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.


RESULTS
There was a statistically significant improvement with the feedback return to the reservoir, with up to nearly 60% more aerosol delivered.


CONCLUSIONS
This improvement in aerosol delivery is encouraging, but more comprehensive studies are needed before such a device could be implemented clinically.
Quong
Michael C
MC
Department of Electrical and Computer Engineering, University of Alberta, 9107 116 Street, Edmonton, Alberta T6G2V4 Canada. mquong@ualberta.ca
Thébaud
Bernard
B
Finlay
Warren H
WH
D000280:Administration, Inhalation; D000335:Aerosol Propellants / Q000008:administration & dosage*; D004526:Efficiency; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D009330:Nebulizers and Vaporizers
D000335:Aerosol Propellants