Biomedical Engineering Reference
In-Depth Information
Ta b l e 7 . 1 0
Biometric and spirometric parameters of the asthmatic children and the healthy chil-
dren used for comparison. Values are presented as mean
standard deviation values; % pred:
predicted values; VC: vital capacity; FEV1: forced expiratory volume in one second; FEF: forced
expiratory flow; MEF75/25: mean expiratory flow at 75 %, respectively at 25 % capacity; NA: data
not available
±
Asthma
(19)
Healthy
(16)
Female/male
3/16
13/3
Age (yrs)
11
.
05
±
4
.
7
9
.
66
±
0
.
47
Height (m)
1
.
40
±
0
.
17
1
.
39
±
0
.
07
Weight (kg)
36
.
25
±
15
.
58
32
.
3
±
6
.
34
FEF/VC
%pred
85
.
31
±
31
.
15
NA
FEV
1
/VC
%pred
97
.
75
±
12
.
83
NA
MEF
75
/
25 (l)
2
.
12
±
0
.
95
NA
The healthy children had no history of pulmonary disease, and were selected
using a specific questionnaire. The questionnaire verified the absence of dyspnoea,
chronic cough, wheeze in the chest, etc.
In order to validate the measurements in healthy children, the real part of the
complex impedance evaluated at 6 Hz (
R
6) was predicted from
R
6
·
h
2
=
0
.
0017
−
0
.
5407
·
h
+
47
.
7323
(7.14)
with
h
the height in (cm) [
33
]. All subjects were within the 95 % confidence interval
values.
The second children group was diagnosed with
asthma
. Asthma denotes a pul-
monary disease in which there is obstruction to the flow of air out of the lungs,
but the obstruction is usually reversible and between attacks of asthma the flow of
air through the airways is usually good [
17
,
19
,
161
]. Asthma is caused by chronic
(ongoing, long-term) inflammation of the airways, making them highly sensitive
to various triggers. Such triggers are usually: indoor and outdoor allergens, indoor
and outdoor dust, exercise. In an asthma attack, the muscles in the airways contract
(bronchospasm), causing narrowing of the airway walls. With proper treatment, peo-
ple with asthma can have fewer and less severe attacks; while without treatment,
they will have more frequent and more severe asthma attacks and can even die.
Asthma can be controlled using specific medication (inhaled steroids).
This study was approved by the local Ethics Committee of the University Hospi-
tal Antwerp (UZA) and informed consent was obtained from all volunteers before
inclusion in the study. The study involved 19 asthmatic children and their corre-
sponding biometric and spirometric values are given in Table
7.10
. The measure-
ments were performed during the December 2008-March 2009 time interval.
The protocol in this clinical trial was as follows: initial measurements of FOT
and spirometry were performed, followed by a bronchodilatator test. Typically, the
spontaneous improvement of the symptoms mentioned above, after the bronchodi-
latator use, is also an indicative of asthma (
>
12 % improvement of forced expira-
