Biomedical Engineering Reference
In-Depth Information
Fig. 7.8
Bode plots for the
COPD group
Ta b l e 7 . 7
Estimated and derived model parameters and modeling errors for the healthy and COPD
groups. Values are given as mean
±
standard deviation; values in brackets indicate the correspond-
ing 95 % confidence intervals
Healthy
COPD
L
r
0
.
032
±
0
.
029 (0.019, 0.045)
0
.
016
±
0
.
007 (0.013, 0.019)
1
/C
r
1
.
59
±
1
.
10 (1.09, 2.08)
2
.
81
±
1
.
45 (2.15, 3.47)
α
r
0
.
42
±
0
.
08 (0.38, 0.47)
0
.
56
±
0
.
07 (0.53, 0.60)
β
r
0
.
75
±
0
.
11 (0.70, 0.80)
0
.
52
±
0
.
10 (0.47, 0.56)
G
r
0
.
44
±
0
.
15 (0.37, 0.50)
1
.
77
±
0
.
73 (1.43, 2.10)
H
r
1
.
49
±
1
.
14 (0.98, 2.00)
2
.
15
±
1
.
30 (1.55, 2.74)
η
r
0
.
41
±
0
.
21 (0.32, 0.51)
0
.
99
±
0
.
41 (0.80, 1.18)
R
6
0
.
13
±
0
.
05 (0.11, 0.16)
0
.
33
±
0
.
07 (0.29, 0.36)
Frez
10
.
48
±
3
.
56 (8.75, 13.87)
20
.
58
±
8
.
98 (11.89, 30.27)
QF
6
0
.
09
±
0
.
09 (0.02, 0.17)
0
.
55
±
0
.
24 (0.44, 0.66)
PF
6
0
.
99
±
0
.
01 (0.98, 0.99)
0
.
86
±
0
.
08 (0.82, 0.90)
E
R
0
.
02
±
0
.
01
0
.
03
±
0
.
01
E
X
0
.
013
±
0
.
006
0
.
02
±
0
.
006
E
T
0
.
02
±
0
.
01
0
.
04
±
0
.
01
the healthy group. The physiological effects of chronic emphysema are extremely
varied, depending on the severity of the disease and on the relative degree of bron-
chiolar obstruction versus lung parenchymal destruction [
6
]. Firstly, the bronchio-
lar obstruction greatly increases airway resistance and results in increased work of
breathing. It is especially difficult for the person to move air through the bronchioles
during expiration because the compressive force on the outside of the lung not only
compresses the alveoli but also compresses the bronchioles, which further increase
their resistance to expiration. This might explain the decreased values for inertance
(air mass acceleration), captured by the values of
L
r
.
Secondly, the marked loss of lung parenchyma greatly decreases the elastin cross-
links, resulting in loss of attachments [
64
]. The latter can be directly related to
