2004 OPEN FORUM Abstracts
EVALUATION OF PNEUMATIC NEBULIZERS IN AN UPRIGHT AND ANGLED POSITION. Mike Rejaey, RRT; Dean R. Hess, PhD, RRT, FAARC.
Massachusetts
General Hospital and Harvard Medical School, Boston MA.
Background:
Pneumatic jet nebulizers are available from many manufacturers. To
our knowledge, there have been no published reports of the effect of
nebulizer position on its performance.
Hypothesis: Albuterol
delivery differs among commercially available nebulizers and is
affected by nebulizer position.
Methods: A double-sided test
lung (Michigan Instruments; Grand Rapids, MI) was used to simulate
spontaneous breathing. One side of the test lung was attached to a
ventilator (Puritan-Bennett 7200) and lifted the contralateral side
to simulate spontaneous breathing. The lung model simulated breathing
at 12 breaths/min, I:E ratio of 1:2 with a sine wave pattern, and
tidal volume of 0.5 L. The breathing pattern was confirmed with a
pneumotachometer placed at the opening to the lung model. The
nebulizer was filled with 4 mL containing 2.5 mg of albuterol and
operated at 8 L/min until nebulization was complete. To measure
albuterol output from the nebulizer, a Puritan-Bennett D/Flex filter
was attached to the mouthpiece. To measure particle size, the inlet
of a cascade impactor was placed at the mouthpiece and a bias flow
equal to the aspiration rate of the impactor was added between it and
the test lung. Nebulizers from 3 manufactures were assessed (n = 3
each): Airlife Misty Max 10™ (Allegiance Healthcare, McGaw
Park, IL), Micro Mist® (Hudson, Temecula, CA), and VixOne
(Westmed, Lakewood, CO). Albuterol washed from the filter and from
the stages of the cascade impactor was measured by UV
spectrophometry. Fine particle mass was calculated as the mass of
particles with a size < 4.7 microns. Nebulizers were evaluated in
both an upright (vertical) position and turned 60 degrees to the
side.
Results: There was a significant difference in fine
particle mass output of the nebulizers in both the upright (Figure 1)
and angled (Figure 2) positions (P < 0.001 in each case). There
was a significant decrease in nebulizer output when nebulizers were
operated at an angle (P < 0.001). There was a significant
interaction effect between nebulizers and nebulizer position (P =
0.003), meaning that operating the nebulizer at an angle affected the
performance of some nebulizers more than others.
Conclusions:
Albuterol delivery differs among commercially available nebulizers.
The output of the nebulizer may be decreased significantly if the
nebulizer is not held in a vertical postion. The impact of these
findings on patient outcomes should be confirmed in clinical studies.
(Supported, in part, by an unrestricted grant from Cardinal
Healthcare).
