Biomedical Engineering Reference
In-Depth Information
Fig. 10.10
Box-whisker plots of impactor mass by inhaler and cascade impactor configuration.
The mean is represented by the tick mark at the center of the line (
From
[
26
]—
used with
permission
)
Table 10.5
Summary statistics and 95% confidence intervals on ratio of standard deviations of
abbreviated to full configurations for metrics related to inhaler APSD (
From
[
26
]—
used with
permission
)
95% CI
a
on ratio of
SDs of abbreviated
to full configuration
ISM
ACI 38.97 1.57 4.07 -
AIM-QC 38.96 2.68 6.87 [0.93; 3.05]
LPM/SPM
ACI 2.70 0.28 9.98 -
AIM-QC 2.69 0.35 12.83 [0.68; 2.24]
a
Inclusion of 1.00 in confidence interval (CI) indicates no statistically significant difference
Impactor
configuration
SD [repeatabi-
lity] (
Coefficient of
variation (%)
Metric
Mean (
μ
g)
μ
g)
Separate estimates of variability were made for each metric (
ISM
,
LPM/SPM
with the AIM-QC and full-resolution ACI) and
FPM
(identical with
CPM
in terms
of precision) for the AIM-pHRT and ACI. The estimates of precision associated
with all these metrics obtained by the appropriate abbreviated impactor were
substantially equivalent to the corresponding metrics with the full-resolution system
(Fig.
10.11
and Tables
10.5
and
10.6
).
Interestingly, all these metrics consistently tracked minor differences between
the six inhalers that were used in the investigation (Fig.
10.11b, d
, f). When the size
fractions from either abbreviated impactor were compared with the corresponding
cumulative mass-weighted APSD data from the ACI (Fig.
10.12
), excellent agree-
ment was apparent in almost all instances. However, an unexpected outcome was
the magnitude of the positive bias associated with
EPF
measured by the AIM-pHRT
system, which was almost 8% greater than the corresponding full-resolution data
(Table
10.6
), illustrated in the comparison of this metric with the expected value
from the ACI (Fig.
10.12
).
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