2006 OPEN FORUM Abstracts
THE EFFECT OF REPEATED NEBULIZATION OF NORMAL SALINE THROUGH A SMALL VOLUME NEBULIZER ON DELIVERED PARTICLE SIZE
Sorenson
HM. Fling D, Wilson W, Rodriguez A, and
Lombardo A . The University of Texas
Health Science Center, San Antonio, TX.
Background: There is tremendous growth in the inhaled
drug market both in the USA and worldwide.
The
pulmonary drug delivery market is projected to exceed $36 billion in sales by
2006. Small volume nebulizers (SVN) are
used in many hospitals to deliver aerosolized medications to pulmonary
patients. Stable pulmonary patients also
use SVNs in the home for extended periods of time. To effectively deliver
aerosol to the parenchyma, devices should deliver a stable mist with particles
in the range of 0.5µm to 4.70µm. Because
most medications delivered by SVNs are diluted in normal saline (0.9%), this
study was conducted to determine if repeated nebulization
with normal saline had any effect on the delivered particle size.
Method: SVN treatments similar to those given in a hospital were simulated in the laboratory using normal saline. A Hudson RCI MicroMist SVN was used. 3.0 mls of 0.9% saline was nebulized using an
air flowmeter set at 8 LPM, a total of 42 times, equivalent to 7 days of Q4
treatments. Between simulations, all of
the nebulizer components were placed on a paper towel and allowed to air dry. An
additional 42 breathing treatments were simulated with the same SVN to mimic 14
days of Q4 treatments. The average run
time for 42 and 84 simulations respectively was 9.13 minutes and 9.15
minutes. Particle size was measured
using a Model 3321 Aerodynamic Particle Sizer manufactured by TSI, Inc. Measurements were made after 42 uses and
again after 84 uses. For comparison
purposes, particle size from a new Hudson RCI MicroMist SVN was also
measured.
Results: See Table 1.0
Conclusion: This study indicates that repeated nebulization of normal saline through an SVN
results in change in particle size; in number per cm3, surface area
per cm3 and in mass per meter3 (shown on table below).
There were significant differences in particles between the new SVN, one used
42 times and then reused an additional 42 times. Significant changes happened between the 42nd
and 84th simulated treatment. Measurements were not done between the 42nd and
84th nebulization. Limitations to this study include the use of two different SVNs.
Failure to initially measure particle size required the use of a new Hudson RCI MicroMist SVN at the completion
of the study, to determine particle size from an unused SVN; additionally,
repeated measurements were not done; only a single measurement was done on the new SVN, once after 42 uses and again
after 84 uses. Based on the results of this study it is our
conclusion that a study similar to this should be repeated. If the results are comparable, further
studies may be warranted to explore what role different medications added to
normal saline have on
particle size generation from repeated use of SVNs.
Table 1.0 Nebulizer
Study; Mass (mg) per Cubic Meter
| N | Mean (SD) | SEM | Median | Range | P-value | |
| After 0 nebulizations | 51 | 0.59 (0.92) | 0.13 | 0.12 | 0 to 3.77 | |
| After 42 nebulizations | 51 | 0.56 (0.87) | 0.12 | 0.13 | 0 to 3.7 | |
| After 84 nebulizations | 51 | 3.61 (6.41) | 0.9 | 0.32 | 0 to 25.7 | |
| Change from 0 to 42 | 51 | -0.04 (0.07) | 0.01 | 0 | -0.27 to 0.02 | 0.091 |
| Change from 0 to 84 | 51 | 3.02 (5.49) | 0.77 | 0.2 | 0 to 21.93 | <0.0011 |
| Change from 42 to 84 | 51 | 3.05 (5.55) | 0.78 | 0.19 | 0 to 22 | <0.0011 |
| Linear trend | <0.0012 |
1. Sign test
2. Repeated measures linear
model of log (mass) on usage (0, 42, 84)