In vitro comparison of five nebulizers during noninvasive ventilation: analysis of inhaled and lost doses

Background: Few studies on performance comparison of nebulizer systems coupled with a single-limb circuit bilevel ventilator are available. Most of these data compared the aerosol drug delivery for only two different systems. Using an adult lung bench model of noninvasive ventilation, we compared inhaled and lost doses of three nebulizer systems coupled with a single-limb circuit bilevel ventilator, as well as the influence of the nebulizer position.

Method: Three vibrating mesh nebulizers (Aeroneb(®) Pro, Aeroneb(®) Solo, and NIVO(®)), one jet nebulizer (Sidestream(®)), and one ultrasonic nebulizer (Servo Ultra Nebulizer 145(®)) coupled with a bilevel ventilator were tested. They were charged with amikacin solution (500 mg/4 mL) and operated at two different positions: before and after the exhalation port (starting from the lung). The inhaled dose, the expiratory wasted dose, and the estimated lost dose were assessed by the residual gravimetric method.

Results: The doses varied widely among the nebulizer types and position. When the nebulizer was positioned before the exhalation port, the vibrating mesh nebulizer delivered the highest inhaled dose (p<0.001), the jet nebulizer the highest expiratory wasted dose (p<0.001), and the ultrasonic device the highest total lost dose (p<0.001). When the nebulizer was positioned after the exhalation port, the vibrating mesh nebulizers delivered the highest inhaled (p<0.001) and expiratory wasted doses (p<0.001), and the ultrasonic device the highest total lost dose (p<0.001). The most efficient nebulizers were NIVO and Aeroneb Solo when placed before the exhalation port.

Conclusions: In a single-limb circuit bilevel ventilator, vibrating mesh nebulizers positioned between the exhalation port and lung model are more efficient for drug delivery compared with jet or ultrasonic nebulizers. In this position, the improved efficiency of vibrating mesh nebulizers was due to an increase in the inhaled dose and a reduction in the exhaled wasted dose compared with placement between the ventilator and the expiratory port. Because of the high total lost dose, the ultrasonic device should not be recommended. Nebulizer placement before the exhalation port increased the inhaled dose and decreased the expiratory wasted dose, except for the jet nebulizer.